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3D-Printed MEMS in Italy
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Towards a Point-of-Care Test of CD4+ T Lymphocyte Concentrations for Immune Status Monitoring with Magnetic Flow Cytometry
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Piezoelectric Micromachined Ultrasonic Transducers with Micro-Hole Inter-Etch and Sealing Process on (111) Silicon Wafer
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Femtosecond Laser Percussion Drilling of Silicon Using Repetitive Single Pulse, MHz-, and GHz-Burst Regimes
Journal Description
Micromachines
Micromachines
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Impact Factor:
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5-Year Impact Factor:
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Latest Articles
Degradation Induced by Total Ionizing Dose and Hot Carrier Injection in SOI FinFET Devices
Micromachines 2024, 15(8), 1026; https://doi.org/10.3390/mi15081026 (registering DOI) - 11 Aug 2024
Abstract
The working environment of electronic devices in the aerospace field is harsh. In order to ensure the reliable application of the SOI FinFET, the total ionizing dose (TID) and hot carrier injecting (HCI) reliability of an SOI FinFET were investigated in this study.
[...] Read more.
The working environment of electronic devices in the aerospace field is harsh. In order to ensure the reliable application of the SOI FinFET, the total ionizing dose (TID) and hot carrier injecting (HCI) reliability of an SOI FinFET were investigated in this study. First, the influence of TID on the device was simulated. The results show that TID causes the threshold voltage to decrease and the off-state current and subthreshold swing to increase. TID causes more damage to the device at high temperature and also reduces the saturation drain current of the device. HCI causes the device threshold voltage to increase and the saturation drain current to decrease. The HCI is more severe at high temperatures. Finally, the coupling effects of the two were simulated, and the results show that the two effects cancel each other out, and the degradation of various electrical characteristic parameters is different under different coupling modes.
Full article
Open AccessArticle
Fragmentation Characteristics of Bubbles in a Throttling Hole Pipe
by
Yufeng Zhang, Zhijie Huang and Lixia Sun
Micromachines 2024, 15(8), 1025; https://doi.org/10.3390/mi15081025 (registering DOI) - 11 Aug 2024
Abstract
To enhance the performance of tubular microbubble generators, the Volume of Fluid (VOF) multiphase flow model in COMSOL Multiphysics was used to simulate the bubble fragmentation characteristics within a throttling hole microbubble generator. The effects of the inlet speed of the throttling hole
[...] Read more.
To enhance the performance of tubular microbubble generators, the Volume of Fluid (VOF) multiphase flow model in COMSOL Multiphysics was used to simulate the bubble fragmentation characteristics within a throttling hole microbubble generator. The effects of the inlet speed of the throttling hole pipe, the diameter of the throttling hole, and the length of the expansion section on bubble fragmentation performance were analyzed. The results indicated that an increase in the inlet speed of the throttling hole pipe gradually improved the bubble fragmentation performance. However, an increase in the throttling hole diameter significantly reduced the bubble fragmentation performance. Changes in the length of the expansion section had a minor impact on the bubble fragmentation performance. Experimental methods were used to verify the characteristics of bubble fragmentation, and it was found that the simulation and experimental results were consistent. This provides a theoretical basis and practical guidance for the design optimization of tubular microbubble generators.
Full article
(This article belongs to the Topic Micro/Nanofluidics and Structures Based Sensing, Material Processing and Energy Conversion)
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Show Figures
![](https://pub.mdpi-res.com/micromachines/micromachines-15-01025/article_deploy/html/images/micromachines-15-01025-g001-550.jpg?1723373627)
Figure 1
Figure 1
<p>The fabrication process of throttling hole type microbubble generator.</p> Full article ">Figure 2
<p>Bubble fragmentation experimental principle diagram.</p> Full article ">Figure 3
<p>Experimental device diagram.</p> Full article ">Figure 4
<p>Calculation method for the number of bubbles inside the orifice type. (<b>a</b>) Quantity recognition flowchart; (<b>b</b>) Quantity recognition steps.</p> Full article ">Figure 5
<p>Orifice plate structure diagram: (<b>a</b>) Traditional throttling hole pipe structure diagram; (<b>b</b>) New type throttling hole pipe structure diagram.</p> Full article ">Figure 6
<p>The grid partitioning of the model.</p> Full article ">Figure 7
<p>Grid independence verification.</p> Full article ">Figure 8
<p>Schematic of the Experimental Procedure.</p> Full article ">Figure 9
<p>Cloud diagram of the bubble fragmentation process.</p> Full article ">Figure 10
<p>Fragmentation transients and velocity clouds of bubbles inside a throttle orifice tube: (<b>a</b>) transitional diagram of bubble development in the throttling orifice tube; (<b>b</b>) velocity field map of the flow inside the throttling orifice tube.</p> Full article ">Figure 11
<p>Fragmentation characteristics of bubbles at different inlet velocities: (<b>a</b>) transient diagrams of bubble fragmentation under different inlet velocities; (<b>b</b>) diameter diagram of bubbles after fragmentation at different inlet velocities.</p> Full article ">Figure 12
<p>Fragmentation characteristics of bubbles at different inlet velocities.</p> Full article ">Figure 13
<p>Bubble fragmentation performance under different throttling aperture: (<b>a</b>) Transient diagram of bubble fragmentation under different orifice diameters; (<b>b</b>) Diameter diagram of bubbles after fragmentation under different orifice diameters.</p> Full article ">Figure 14
<p>Flow characteristics of fluid under different throttling apertures: (<b>a</b>) Variation in velocity along the axis inside the throttling orifice tube; (<b>b</b>) Variation in pressure along the axis inside the throttling orifice tube; (<b>c</b>) Variation of turbulent dissipation rate along the axis inside the throttling orifice tube; (<b>d</b>) Variation of turbulent kinetic energy along the axis inside the throttling orifice tube.</p> Full article ">Figure 14 Cont.
<p>Flow characteristics of fluid under different throttling apertures: (<b>a</b>) Variation in velocity along the axis inside the throttling orifice tube; (<b>b</b>) Variation in pressure along the axis inside the throttling orifice tube; (<b>c</b>) Variation of turbulent dissipation rate along the axis inside the throttling orifice tube; (<b>d</b>) Variation of turbulent kinetic energy along the axis inside the throttling orifice tube.</p> Full article ">Figure 15
<p>Fragmentation characteristics of bubbles under different expansion section lengths.</p> Full article ">Figure 16
<p>Flow characteristics of fluid under different expansion section lengths: (<b>a</b>) Variation of velocity along the axis inside the throttling orifice tube; (<b>b</b>) Variation of pressure along the axis inside the throttling orifice tube; (<b>c</b>) Variation of turbulent dissipation rate along the axis inside the throttling orifice tube; (<b>d</b>) Variation of turbulent kinetic energy along the axis inside the throttling orifice tube.</p> Full article ">Figure 17
<p>Effect of gas-liquid ratio on bubble diameter in orifice tube.</p> Full article ">Figure 18
<p>Results of changes in bubble particle size under different inlet velocities.</p> Full article ">Figure 19
<p>The bubble generator produces microfine air bubbles.</p> Full article ">Figure 20
<p>Results of changes in bubble particle size under different throttling apertures.</p> Full article ">Figure 21
<p>Results of changes in bubble size under different expansion section lengths.</p> Full article ">
<p>The fabrication process of throttling hole type microbubble generator.</p> Full article ">Figure 2
<p>Bubble fragmentation experimental principle diagram.</p> Full article ">Figure 3
<p>Experimental device diagram.</p> Full article ">Figure 4
<p>Calculation method for the number of bubbles inside the orifice type. (<b>a</b>) Quantity recognition flowchart; (<b>b</b>) Quantity recognition steps.</p> Full article ">Figure 5
<p>Orifice plate structure diagram: (<b>a</b>) Traditional throttling hole pipe structure diagram; (<b>b</b>) New type throttling hole pipe structure diagram.</p> Full article ">Figure 6
<p>The grid partitioning of the model.</p> Full article ">Figure 7
<p>Grid independence verification.</p> Full article ">Figure 8
<p>Schematic of the Experimental Procedure.</p> Full article ">Figure 9
<p>Cloud diagram of the bubble fragmentation process.</p> Full article ">Figure 10
<p>Fragmentation transients and velocity clouds of bubbles inside a throttle orifice tube: (<b>a</b>) transitional diagram of bubble development in the throttling orifice tube; (<b>b</b>) velocity field map of the flow inside the throttling orifice tube.</p> Full article ">Figure 11
<p>Fragmentation characteristics of bubbles at different inlet velocities: (<b>a</b>) transient diagrams of bubble fragmentation under different inlet velocities; (<b>b</b>) diameter diagram of bubbles after fragmentation at different inlet velocities.</p> Full article ">Figure 12
<p>Fragmentation characteristics of bubbles at different inlet velocities.</p> Full article ">Figure 13
<p>Bubble fragmentation performance under different throttling aperture: (<b>a</b>) Transient diagram of bubble fragmentation under different orifice diameters; (<b>b</b>) Diameter diagram of bubbles after fragmentation under different orifice diameters.</p> Full article ">Figure 14
<p>Flow characteristics of fluid under different throttling apertures: (<b>a</b>) Variation in velocity along the axis inside the throttling orifice tube; (<b>b</b>) Variation in pressure along the axis inside the throttling orifice tube; (<b>c</b>) Variation of turbulent dissipation rate along the axis inside the throttling orifice tube; (<b>d</b>) Variation of turbulent kinetic energy along the axis inside the throttling orifice tube.</p> Full article ">Figure 14 Cont.
<p>Flow characteristics of fluid under different throttling apertures: (<b>a</b>) Variation in velocity along the axis inside the throttling orifice tube; (<b>b</b>) Variation in pressure along the axis inside the throttling orifice tube; (<b>c</b>) Variation of turbulent dissipation rate along the axis inside the throttling orifice tube; (<b>d</b>) Variation of turbulent kinetic energy along the axis inside the throttling orifice tube.</p> Full article ">Figure 15
<p>Fragmentation characteristics of bubbles under different expansion section lengths.</p> Full article ">Figure 16
<p>Flow characteristics of fluid under different expansion section lengths: (<b>a</b>) Variation of velocity along the axis inside the throttling orifice tube; (<b>b</b>) Variation of pressure along the axis inside the throttling orifice tube; (<b>c</b>) Variation of turbulent dissipation rate along the axis inside the throttling orifice tube; (<b>d</b>) Variation of turbulent kinetic energy along the axis inside the throttling orifice tube.</p> Full article ">Figure 17
<p>Effect of gas-liquid ratio on bubble diameter in orifice tube.</p> Full article ">Figure 18
<p>Results of changes in bubble particle size under different inlet velocities.</p> Full article ">Figure 19
<p>The bubble generator produces microfine air bubbles.</p> Full article ">Figure 20
<p>Results of changes in bubble particle size under different throttling apertures.</p> Full article ">Figure 21
<p>Results of changes in bubble size under different expansion section lengths.</p> Full article ">
Open AccessArticle
Hybrid Fibers with Subwavelength-Scale Liquid Core for Highly Sensitive Sensing and Enhanced Nonlinearity
by
Caoyuan Wang, Ruowei Yu, Yucheng Ye, Cong Xiong, Muhammad Hanif Ahmed Khan Khushik and Limin Xiao
Micromachines 2024, 15(8), 1024; https://doi.org/10.3390/mi15081024 (registering DOI) - 11 Aug 2024
Abstract
Interest grows in designing silicon-on-insulator slot waveguides to trap optical fields in subwavelength-scale slots and developing their optofluidic devices. However, it is worth noting that the inherent limitations of the waveguide structures may result in high optical losses and short optical paths, which
[...] Read more.
Interest grows in designing silicon-on-insulator slot waveguides to trap optical fields in subwavelength-scale slots and developing their optofluidic devices. However, it is worth noting that the inherent limitations of the waveguide structures may result in high optical losses and short optical paths, which challenge the device’s performance in optofluidics. Incorporating the planar silicon-based slot waveguide concept into a silica-based hollow-core fiber can provide a perfect solution to realize an efficient optofluidic waveguide. Here, we propose a subwavelength-scale liquid-core hybrid fiber (LCHF), where the core is filled with carbon disulfide and surrounded by a silicon ring in a silica background. The waveguide properties and the Stimulated Raman Scattering (SRS) effect in the LCHF are investigated. The fraction of power inside the core of 56.3% allows for improved sensitivity in optical sensing, while the modal Raman gain of 23.60 m−1·W−1 is two times larger than that generated around a nanofiber with the interaction between the evanescent optical field and the surrounding Raman media benzene-methanol, which enables a significant low-threshold SRS effect. Moreover, this in-fiber structure features compactness, robustness, flexibility, ease of implementation in both trace sample consumption and reasonable liquid filling duration, as well as compatibility with optical fiber systems. The detailed analyses of the properties and utilizations of the LCHF suggest a promising in-fiber optofluidic platform, which provides a novel insight into optofluidic devices, optical sensing, nonlinear optics, etc.
Full article
(This article belongs to the Special Issue The 15th Anniversary of Micromachines)
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![](https://pub.mdpi-res.com/micromachines/micromachines-15-01024/article_deploy/html/images/micromachines-15-01024-g001-550.jpg?1723366872)
Figure 1
Figure 1
<p>Schematics of the proposed LCHF in (<b>a</b>) 3D view and (<b>b</b>) cross-section view.</p> Full article ">Figure 2
<p>Evolution of normalized modal intensity distributions of LCHFs with the core diameter <span class="html-italic">d</span> and the silicon layer thickness <span class="html-italic">t</span> of: core diameter = 100 nm, (<b>a1</b>) <span class="html-italic">t</span> = 50 nm, (<b>a2</b>) <span class="html-italic">t</span> = 100 nm, (<b>a3</b>) <span class="html-italic">t</span> = 200 nm; core diameter = 250 nm, (<b>b1</b>) <span class="html-italic">t</span> = 50 nm, (<b>b2</b>) <span class="html-italic">t</span> = 100 nm, (<b>b3</b>) <span class="html-italic">t</span> = 200 nm; core diameter = 400 nm, (<b>c1</b>) <span class="html-italic">t</span> = 50 nm, (<b>c2</b>) <span class="html-italic">t</span> = 100 nm, (<b>c3</b>) <span class="html-italic">t</span> = 200 nm. Insets correspond to a quarter of the mode patterns for fundamental modes (HE<sub>11</sub> modes, polarized along the <span class="html-italic">y</span>-direction).</p> Full article ">Figure 3
<p>(<b>a</b>,<b>b</b>) Variations in the fraction of power in the core <span class="html-italic">f</span> in the LCHF with different parameters. (<b>c</b>) Variations in the fraction of power in the core <span class="html-italic">f</span> when the core is filled with different liquids, with different thicknesses of silicon layer <span class="html-italic">t</span>. (<b>d</b>) Variations in the optimal silicon layer thickness <span class="html-italic">t</span>, and the corresponding peak power fraction <span class="html-italic">f,</span> with the core diameter <span class="html-italic">d</span>.</p> Full article ">Figure 4
<p>Normalized transverse intensity profiles of the HE<sub>11</sub> pump mode and the HE<sub>11</sub> first-order Stokes mode in two orthogonal directions for a CS<sub>2</sub>-core LCHF structure with <span class="html-italic">d</span> of 150 nm and <span class="html-italic">t</span> of 136 nm.</p> Full article ">Figure 5
<p>Variations in the modal Raman gain <span class="html-italic">g<sub>s</sub></span> with (<b>a</b>) different core diameters of 100 nm, 250 nm, and 400 nm as functions of the thickness of silicon layer, (<b>b</b>) different thicknesses of 50 nm, 100 nm, and 200 nm as functions of the core diameter. Variations in the effective mode area <span class="html-italic">A<sub>eff</sub></span>, with (<b>c</b>) different core diameters of 100 nm, 250 nm, and 400 nm as functions of the thickness of silicon layer, (<b>d</b>) different thicknesses of 50 nm, 100 nm, and 200 nm as functions of the core diameter.</p> Full article ">Figure 6
<p>Variations in the optimal silicon layer thickness <span class="html-italic">t</span> and the corresponding modal Raman gain <span class="html-italic">g<sub>s</sub></span> with the core diameter <span class="html-italic">d</span>.</p> Full article ">Figure 7
<p>Evolutions of the pump and the first-order Stokes powers, with the input power for the LCHF with the highest modal Raman gain (<span class="html-italic">d</span> of 150 nm and <span class="html-italic">t</span> of 136 nm) in a CW experiment. The dash line represents the critical power.</p> Full article ">
<p>Schematics of the proposed LCHF in (<b>a</b>) 3D view and (<b>b</b>) cross-section view.</p> Full article ">Figure 2
<p>Evolution of normalized modal intensity distributions of LCHFs with the core diameter <span class="html-italic">d</span> and the silicon layer thickness <span class="html-italic">t</span> of: core diameter = 100 nm, (<b>a1</b>) <span class="html-italic">t</span> = 50 nm, (<b>a2</b>) <span class="html-italic">t</span> = 100 nm, (<b>a3</b>) <span class="html-italic">t</span> = 200 nm; core diameter = 250 nm, (<b>b1</b>) <span class="html-italic">t</span> = 50 nm, (<b>b2</b>) <span class="html-italic">t</span> = 100 nm, (<b>b3</b>) <span class="html-italic">t</span> = 200 nm; core diameter = 400 nm, (<b>c1</b>) <span class="html-italic">t</span> = 50 nm, (<b>c2</b>) <span class="html-italic">t</span> = 100 nm, (<b>c3</b>) <span class="html-italic">t</span> = 200 nm. Insets correspond to a quarter of the mode patterns for fundamental modes (HE<sub>11</sub> modes, polarized along the <span class="html-italic">y</span>-direction).</p> Full article ">Figure 3
<p>(<b>a</b>,<b>b</b>) Variations in the fraction of power in the core <span class="html-italic">f</span> in the LCHF with different parameters. (<b>c</b>) Variations in the fraction of power in the core <span class="html-italic">f</span> when the core is filled with different liquids, with different thicknesses of silicon layer <span class="html-italic">t</span>. (<b>d</b>) Variations in the optimal silicon layer thickness <span class="html-italic">t</span>, and the corresponding peak power fraction <span class="html-italic">f,</span> with the core diameter <span class="html-italic">d</span>.</p> Full article ">Figure 4
<p>Normalized transverse intensity profiles of the HE<sub>11</sub> pump mode and the HE<sub>11</sub> first-order Stokes mode in two orthogonal directions for a CS<sub>2</sub>-core LCHF structure with <span class="html-italic">d</span> of 150 nm and <span class="html-italic">t</span> of 136 nm.</p> Full article ">Figure 5
<p>Variations in the modal Raman gain <span class="html-italic">g<sub>s</sub></span> with (<b>a</b>) different core diameters of 100 nm, 250 nm, and 400 nm as functions of the thickness of silicon layer, (<b>b</b>) different thicknesses of 50 nm, 100 nm, and 200 nm as functions of the core diameter. Variations in the effective mode area <span class="html-italic">A<sub>eff</sub></span>, with (<b>c</b>) different core diameters of 100 nm, 250 nm, and 400 nm as functions of the thickness of silicon layer, (<b>d</b>) different thicknesses of 50 nm, 100 nm, and 200 nm as functions of the core diameter.</p> Full article ">Figure 6
<p>Variations in the optimal silicon layer thickness <span class="html-italic">t</span> and the corresponding modal Raman gain <span class="html-italic">g<sub>s</sub></span> with the core diameter <span class="html-italic">d</span>.</p> Full article ">Figure 7
<p>Evolutions of the pump and the first-order Stokes powers, with the input power for the LCHF with the highest modal Raman gain (<span class="html-italic">d</span> of 150 nm and <span class="html-italic">t</span> of 136 nm) in a CW experiment. The dash line represents the critical power.</p> Full article ">
Open AccessArticle
Research on Polarization Modulation of Electro-Optical Crystals for 3D Imaging Reconstruction
by
Houpeng Sun, Yingchun Li, Huichao Guo, Chenglong Luan, Laixian Zhang, Haijing Zheng and Youchen Fan
Micromachines 2024, 15(8), 1023; https://doi.org/10.3390/mi15081023 (registering DOI) - 11 Aug 2024
Abstract
A method for enhancing the resolution of 3D imaging reconstruction by employing the polarization modulation of electro-optical crystals is proposed. This technique utilizes two polarizers oriented perpendicular to each other along with an electro-optical modulation crystal to achieve high repetition frequency and narrow
[...] Read more.
A method for enhancing the resolution of 3D imaging reconstruction by employing the polarization modulation of electro-optical crystals is proposed. This technique utilizes two polarizers oriented perpendicular to each other along with an electro-optical modulation crystal to achieve high repetition frequency and narrow pulse width gating. By varying the modulation time series of the electro-optical crystal, three-dimensional gray images of the laser at different distances are acquired, and the three-dimensional information of the target is reconstructed using the range energy recovery algorithm. This 3D imaging system can be implemented with large area detectors, independent of the an Intensified Charge-Coupled Device (ICCD) manufacturing process, resulting in improved lateral resolution. Experimental results demonstrate that when imaging a target at the distance of 20 m, the lateral resolution within the region of interest is 2560 × 2160, with a root mean square error of 3.2 cm.
Full article
(This article belongs to the Special Issue Optical and Laser Material Processing)
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Show Figures
![](https://pub.mdpi-res.com/micromachines/micromachines-15-01023/article_deploy/html/images/micromachines-15-01023-g001-550.jpg?1723363759)
Figure 1
Figure 1
<p>Schematic diagram of the modulation process of a crystal by EMCCD imaging.</p> Full article ">Figure 2
<p>Schematic diagram of 3D imaging reconstruction based on polarization modulation gating of electro-optical crystal.</p> Full article ">Figure 3
<p>Signal timing diagram.</p> Full article ">Figure 4
<p>Schematic diagram of crystal polarization-modulated gated 3D imaging: (<b>a</b>) 3D imaging process; (<b>b</b>) 3D imaging restoration.</p> Full article ">Figure 5
<p>Three-dimensional imaging distance–energy diagram: (<b>a</b>) laser pulse and crystal shutter; (<b>b</b>) the relationship between the echo energy and the target distance.</p> Full article ">Figure 6
<p>Schematic diagram of the energy of two echo signals.</p> Full article ">Figure 7
<p>Distance grayscale curve of a trapezoid.</p> Full article ">Figure 8
<p>The propagation of light in an electro-optical crystal.</p> Full article ">Figure 9
<p>SRefractive index ellipsoid.</p> Full article ">Figure 10
<p>Polarization modulation of electro-optical crystal light intensity distribution. (<b>a</b>) the light intensity distribution of the electro-optical crystal in the “off” state; (<b>b</b>) the light intensity distribution of the electro-optical crystal in the “on” state.</p> Full article ">Figure 11
<p>Schematic diagram of crystal polarization modulation.</p> Full article ">Figure 12
<p>The prototype of the 3D imaging system is based on electro-optical crystal polarization modulation.</p> Full article ">Figure 13
<p>Three-dimensional imaging target. (<b>a</b>) semi-ellipsoidal object; (<b>b</b>) satellite object; (<b>c</b>) space station object.</p> Full article ">Figure 14
<p>Waveform diagram of the laser pulse and electro-optic-modulated shutter signal. (<b>a</b>) Laser pulse waveform; (<b>b</b>) The electro-optical crystal modulates the shutter waveform.</p> Full article ">Figure 15
<p>The timing relationship between the laser pulse and electro-optical-modulated shutter signal. (<b>a</b>) The laser pulse signal is tangent to the electro-optical crystal-modulated shutter; (<b>b</b>) The laser pulse signal enters the electro-optical-modulated shutter completely.</p> Full article ">Figure 16
<p>Three-dimensional imaging results. Imaging results of space station (<b>a</b>–<b>c</b>); imaging results of satellite (<b>d</b>–<b>f</b>); and imaging results of semi-ellipsoidal object (<b>g</b>–<b>i</b>).</p> Full article ">Figure 16 Cont.
<p>Three-dimensional imaging results. Imaging results of space station (<b>a</b>–<b>c</b>); imaging results of satellite (<b>d</b>–<b>f</b>); and imaging results of semi-ellipsoidal object (<b>g</b>–<b>i</b>).</p> Full article ">Figure 17
<p>Three-dimensional imaging preprocessing results. (<b>a</b>) preprocessing result of the space station object; (<b>b</b>) preprocessing result of the satellite object; (<b>c</b>) preprocessing result of the semi-ellipsoidal object.</p> Full article ">Figure 18
<p>Three-dimensional imaging distance depth image. (<b>a</b>) distance depth image of the space station object; (<b>b</b>) distance depth image of the satellite object; (<b>c</b>) distance depth image of the semi-ellipsoidal object.</p> Full article ">Figure 19
<p>Three-dimensional imaging point cloud image. (<b>a</b>) point cloud image of the space station object; (<b>b</b>) point cloud image of the satellite object; (<b>c</b>) point cloud image of the semi-ellipsoidal object.</p> Full article ">Figure 20
<p>The target area is selected for evaluation measurements; red squares were selected for evaluation; each red square was 100 × 100 pixels.</p> Full article ">Figure 21
<p>Distance information histogram distribution, the number represents the percentage of distance x.</p> Full article ">Figure 22
<p>The target area is selected for evaluation measurements.</p> Full article ">
<p>Schematic diagram of the modulation process of a crystal by EMCCD imaging.</p> Full article ">Figure 2
<p>Schematic diagram of 3D imaging reconstruction based on polarization modulation gating of electro-optical crystal.</p> Full article ">Figure 3
<p>Signal timing diagram.</p> Full article ">Figure 4
<p>Schematic diagram of crystal polarization-modulated gated 3D imaging: (<b>a</b>) 3D imaging process; (<b>b</b>) 3D imaging restoration.</p> Full article ">Figure 5
<p>Three-dimensional imaging distance–energy diagram: (<b>a</b>) laser pulse and crystal shutter; (<b>b</b>) the relationship between the echo energy and the target distance.</p> Full article ">Figure 6
<p>Schematic diagram of the energy of two echo signals.</p> Full article ">Figure 7
<p>Distance grayscale curve of a trapezoid.</p> Full article ">Figure 8
<p>The propagation of light in an electro-optical crystal.</p> Full article ">Figure 9
<p>SRefractive index ellipsoid.</p> Full article ">Figure 10
<p>Polarization modulation of electro-optical crystal light intensity distribution. (<b>a</b>) the light intensity distribution of the electro-optical crystal in the “off” state; (<b>b</b>) the light intensity distribution of the electro-optical crystal in the “on” state.</p> Full article ">Figure 11
<p>Schematic diagram of crystal polarization modulation.</p> Full article ">Figure 12
<p>The prototype of the 3D imaging system is based on electro-optical crystal polarization modulation.</p> Full article ">Figure 13
<p>Three-dimensional imaging target. (<b>a</b>) semi-ellipsoidal object; (<b>b</b>) satellite object; (<b>c</b>) space station object.</p> Full article ">Figure 14
<p>Waveform diagram of the laser pulse and electro-optic-modulated shutter signal. (<b>a</b>) Laser pulse waveform; (<b>b</b>) The electro-optical crystal modulates the shutter waveform.</p> Full article ">Figure 15
<p>The timing relationship between the laser pulse and electro-optical-modulated shutter signal. (<b>a</b>) The laser pulse signal is tangent to the electro-optical crystal-modulated shutter; (<b>b</b>) The laser pulse signal enters the electro-optical-modulated shutter completely.</p> Full article ">Figure 16
<p>Three-dimensional imaging results. Imaging results of space station (<b>a</b>–<b>c</b>); imaging results of satellite (<b>d</b>–<b>f</b>); and imaging results of semi-ellipsoidal object (<b>g</b>–<b>i</b>).</p> Full article ">Figure 16 Cont.
<p>Three-dimensional imaging results. Imaging results of space station (<b>a</b>–<b>c</b>); imaging results of satellite (<b>d</b>–<b>f</b>); and imaging results of semi-ellipsoidal object (<b>g</b>–<b>i</b>).</p> Full article ">Figure 17
<p>Three-dimensional imaging preprocessing results. (<b>a</b>) preprocessing result of the space station object; (<b>b</b>) preprocessing result of the satellite object; (<b>c</b>) preprocessing result of the semi-ellipsoidal object.</p> Full article ">Figure 18
<p>Three-dimensional imaging distance depth image. (<b>a</b>) distance depth image of the space station object; (<b>b</b>) distance depth image of the satellite object; (<b>c</b>) distance depth image of the semi-ellipsoidal object.</p> Full article ">Figure 19
<p>Three-dimensional imaging point cloud image. (<b>a</b>) point cloud image of the space station object; (<b>b</b>) point cloud image of the satellite object; (<b>c</b>) point cloud image of the semi-ellipsoidal object.</p> Full article ">Figure 20
<p>The target area is selected for evaluation measurements; red squares were selected for evaluation; each red square was 100 × 100 pixels.</p> Full article ">Figure 21
<p>Distance information histogram distribution, the number represents the percentage of distance x.</p> Full article ">Figure 22
<p>The target area is selected for evaluation measurements.</p> Full article ">
Open AccessArticle
A Wideband Millimeter-Wave Dual-Beam Dielectric Resonator Antenna with Substrate Integration Capability
by
Jin Shi, Ranhao Xu, Bowen Wu, Lei Wang and Ruirui Jiang
Micromachines 2024, 15(8), 1022; https://doi.org/10.3390/mi15081022 (registering DOI) - 10 Aug 2024
Abstract
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A wideband dual-beam dielectric resonator antenna (DRA) with substrate integration capability was proposed for millimeter-wave (mm-wave) applications. The four rows of air vias along the x-direction and two extended rectangular patches could shift the undesirable radiation mode upward and move the conical-beam
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A wideband dual-beam dielectric resonator antenna (DRA) with substrate integration capability was proposed for millimeter-wave (mm-wave) applications. The four rows of air vias along the x-direction and two extended rectangular patches could shift the undesirable radiation mode upward and move the conical-beam radiation mode downward, respectively. Thus, the TE211 mode and the TE411 mode of the patch-loaded perforated rectangular substrate integrated dielectric resonator (SIDR) supporting the dual-beam radiation can be retained in the operating band, and their radiation can be improved by the air vias along the y-direction. The T-shaped line coupled dual-slot structure could excite the above two modes, and a dual-slot mode supporting dual-beam radiation could also work. Then, a wideband DRA with a stable dual-beam radiation angle can be achieved, and its impedance matching can be improved by two air slots on two sides. Compared with the state-of-the-art dual-beam antennas, the proposed antenna shows a wider bandwidth, a higher radiation efficiency, and the substrate integration capability of DRA, making it more suitable for mm-wave applications. For demonstration, a 1 × 4 array was designed with the 10 dB impedance matching bandwidth of 41.2% and the directions of the dual beams between ±30° and ±35°.
Full article
![](https://pub.mdpi-res.com/micromachines/micromachines-15-01022/article_deploy/html/images/micromachines-15-01022-g001-550.jpg?1723272959)
Figure 1
Figure 1
<p>Configuration of the proposed dual-beam substrate integrated dielectric resonator antenna (SIDRA) element. (<b>a</b>) Exploded view. (<b>b</b>) Top view. (<b>c</b>) Bottom view.</p> Full article ">Figure 2
<p>Configuration of Ant. I. (<b>a</b>) Top view. (<b>b</b>) Side view.</p> Full article ">Figure 3
<p>Simulated |<span class="html-italic">S</span><sub>11</sub>| and the input impedance of Ant. I. (<b>a</b>) |<span class="html-italic">S</span><sub>11</sub>|. (<b>b</b>) Input impedance (red line: the real part; black line: the imaginary part).</p> Full article ">Figure 4
<p>The simulated results of <span class="html-italic">E</span>-fields and 3-D radiation patterns of Ant. I for (<b>a</b>) mode 1 (the dual-slot mode), (<b>b</b>) mode 2 (the TE<sub>211</sub> mode), (<b>c</b>) mode 3, and (<b>d</b>) mode 4 (the TE<sub>411</sub> mode).</p> Full article ">Figure 5
<p>Top view of the reference antennas and the proposed antenna. (<b>a</b>) Ant. II. (<b>b</b>) Ant. III. (<b>c</b>) Proposed antenna.</p> Full article ">Figure 6
<p>Simulated |<span class="html-italic">S</span><sub>11</sub>| and the realized gain of the reference antennas and the proposed antenna. (<b>a</b>) |<span class="html-italic">S</span><sub>11</sub>|. (<b>b</b>) Realized gain.</p> Full article ">Figure 7
<p>The simulated results of <span class="html-italic">E</span>-fields and 3-D radiation patterns of Ant. II for (<b>a</b>) mode 5, (<b>b</b>) mode 2 (the TE<sub>211</sub> mode), and (<b>c</b>) mode 4 (the TE<sub>411</sub> mode).</p> Full article ">Figure 8
<p>(<b>a</b>) The input impedances of Ant. II and Ant. III in the Smith chart. (<b>b</b>) The simulated frequency variation in different modes in <span class="html-italic">w</span><sub>p</sub>.</p> Full article ">Figure 9
<p>The simulated <span class="html-italic">E</span>-fields and the equivalent magnetic current models of the proposed antenna for (<b>a</b>) the TE<sub>211</sub> mode and (<b>b</b>) the TE<sub>411</sub> mode.</p> Full article ">Figure 10
<p>Simulated |<span class="html-italic">S</span><sub>11</sub>| and the realized gain of the proposed dual-beam SIDRA for different values of (<b>a</b>) <span class="html-italic">l</span><sub>s</sub>, (<b>b</b>) <span class="html-italic">l</span><sub>a</sub>, (<b>c</b>) <span class="html-italic">w</span><sub>p</sub>, and (<b>d</b>) <span class="html-italic">l</span><sub>p</sub>.</p> Full article ">Figure 11
<p>Simulated radiation efficiency and radiation patterns of the proposed antenna element. (<b>a</b>) The radiation efficiency. (<b>b</b>) The <span class="html-italic">E</span>-plane radiation patterns.</p> Full article ">Figure 12
<p>Configuration and photograph of the proposed 1 × 4 antenna array. (<b>a</b>) Configuration. (<b>b</b>) Photograph.</p> Full article ">Figure 13
<p>Simulated and measured |<span class="html-italic">S</span><sub>11</sub>| and gains of the proposed 1 × 4 antenna array. (<b>a</b>) |<span class="html-italic">S</span><sub>11</sub>|. (<b>b</b>) The gains.</p> Full article ">Figure 14
<p>Simulated and measured <span class="html-italic">E</span>-plane radiation patterns of the proposed 1 × 4 antenna array at (<b>a</b>) 25 GHz, (<b>b</b>) 29 GHz, and (<b>c</b>) 33 GHz.</p> Full article ">
<p>Configuration of the proposed dual-beam substrate integrated dielectric resonator antenna (SIDRA) element. (<b>a</b>) Exploded view. (<b>b</b>) Top view. (<b>c</b>) Bottom view.</p> Full article ">Figure 2
<p>Configuration of Ant. I. (<b>a</b>) Top view. (<b>b</b>) Side view.</p> Full article ">Figure 3
<p>Simulated |<span class="html-italic">S</span><sub>11</sub>| and the input impedance of Ant. I. (<b>a</b>) |<span class="html-italic">S</span><sub>11</sub>|. (<b>b</b>) Input impedance (red line: the real part; black line: the imaginary part).</p> Full article ">Figure 4
<p>The simulated results of <span class="html-italic">E</span>-fields and 3-D radiation patterns of Ant. I for (<b>a</b>) mode 1 (the dual-slot mode), (<b>b</b>) mode 2 (the TE<sub>211</sub> mode), (<b>c</b>) mode 3, and (<b>d</b>) mode 4 (the TE<sub>411</sub> mode).</p> Full article ">Figure 5
<p>Top view of the reference antennas and the proposed antenna. (<b>a</b>) Ant. II. (<b>b</b>) Ant. III. (<b>c</b>) Proposed antenna.</p> Full article ">Figure 6
<p>Simulated |<span class="html-italic">S</span><sub>11</sub>| and the realized gain of the reference antennas and the proposed antenna. (<b>a</b>) |<span class="html-italic">S</span><sub>11</sub>|. (<b>b</b>) Realized gain.</p> Full article ">Figure 7
<p>The simulated results of <span class="html-italic">E</span>-fields and 3-D radiation patterns of Ant. II for (<b>a</b>) mode 5, (<b>b</b>) mode 2 (the TE<sub>211</sub> mode), and (<b>c</b>) mode 4 (the TE<sub>411</sub> mode).</p> Full article ">Figure 8
<p>(<b>a</b>) The input impedances of Ant. II and Ant. III in the Smith chart. (<b>b</b>) The simulated frequency variation in different modes in <span class="html-italic">w</span><sub>p</sub>.</p> Full article ">Figure 9
<p>The simulated <span class="html-italic">E</span>-fields and the equivalent magnetic current models of the proposed antenna for (<b>a</b>) the TE<sub>211</sub> mode and (<b>b</b>) the TE<sub>411</sub> mode.</p> Full article ">Figure 10
<p>Simulated |<span class="html-italic">S</span><sub>11</sub>| and the realized gain of the proposed dual-beam SIDRA for different values of (<b>a</b>) <span class="html-italic">l</span><sub>s</sub>, (<b>b</b>) <span class="html-italic">l</span><sub>a</sub>, (<b>c</b>) <span class="html-italic">w</span><sub>p</sub>, and (<b>d</b>) <span class="html-italic">l</span><sub>p</sub>.</p> Full article ">Figure 11
<p>Simulated radiation efficiency and radiation patterns of the proposed antenna element. (<b>a</b>) The radiation efficiency. (<b>b</b>) The <span class="html-italic">E</span>-plane radiation patterns.</p> Full article ">Figure 12
<p>Configuration and photograph of the proposed 1 × 4 antenna array. (<b>a</b>) Configuration. (<b>b</b>) Photograph.</p> Full article ">Figure 13
<p>Simulated and measured |<span class="html-italic">S</span><sub>11</sub>| and gains of the proposed 1 × 4 antenna array. (<b>a</b>) |<span class="html-italic">S</span><sub>11</sub>|. (<b>b</b>) The gains.</p> Full article ">Figure 14
<p>Simulated and measured <span class="html-italic">E</span>-plane radiation patterns of the proposed 1 × 4 antenna array at (<b>a</b>) 25 GHz, (<b>b</b>) 29 GHz, and (<b>c</b>) 33 GHz.</p> Full article ">
Open AccessReview
Comprehensive Review on Research Status and Progress in Precision Grinding and Machining of BK7 Glasses
by
Dayong Yang, Zhiyang Zhang, Furui Wei, Shuping Li, Min Liu and Yuwei Lu
Micromachines 2024, 15(8), 1021; https://doi.org/10.3390/mi15081021 (registering DOI) - 9 Aug 2024
Abstract
BK7 glass, with its outstanding mechanical strength and optical performance, plays a crucial role in many cutting-edge technological fields and has become an indispensable and important material. These fields have extremely high requirements for the surface quality of BK7 glass, and any small
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BK7 glass, with its outstanding mechanical strength and optical performance, plays a crucial role in many cutting-edge technological fields and has become an indispensable and important material. These fields have extremely high requirements for the surface quality of BK7 glass, and any small defects or losses may affect its optical performance and stability. However, as a hard and brittle material, the processing of BK7 glass is extremely challenging, requiring precise control of machining parameters to avoid material fracture or excessive defects. Therefore, how to obtain the required surface quality with lower cost machining techniques has always been the focus of researchers. This article introduces the properties, application background, machining methods, material removal mechanism, and surface and subsurface damage of optical glass BK7 material. Finally, scientific predictions and prospects are made for future development trends and directions for improvement of BK7 glass machining.
Full article
(This article belongs to the Collection Microdevices and Applications Based on Advanced Glassy Materials)
Open AccessArticle
Simulation and Experimental Study on Stress Relaxation Response of Polycrystalline γ-TiAl Alloy under Nanoindentation Based on Molecular Dynamics
by
Junye Li, Chunyu Wang, Jianhe Liu, Xiwei Dong, Jinghe Zhao and Ying Chen
Micromachines 2024, 15(8), 1020; https://doi.org/10.3390/mi15081020 (registering DOI) - 9 Aug 2024
Abstract
This study employed nano-indentation technology, molecular dynamics simulation, and experimental investigation to examine the stress relaxation behaviour of a polycrystalline γ-TiAl alloy. The simulation enabled the generation of a load-time curve, the visualisation of internal defect evolution, and the mapping of stress distribution
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This study employed nano-indentation technology, molecular dynamics simulation, and experimental investigation to examine the stress relaxation behaviour of a polycrystalline γ-TiAl alloy. The simulation enabled the generation of a load-time curve, the visualisation of internal defect evolution, and the mapping of stress distribution across each grain during the stress relaxation stage. The findings indicate that the load remains stable following an initial decline, thereby elucidating the underlying mechanism of load change during stress relaxation. Furthermore, a nano-indentation test was conducted on the alloy, providing insight into the load variation and stress relaxation behaviour under different loading conditions. By comparing the simulation and experimental results, this study aims to guide the theoretical research and practical application of γ-TiAl alloys.
Full article
(This article belongs to the Topic Micro-Mechatronic Engineering)
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![](https://pub.mdpi-res.com/micromachines/micromachines-15-01020/article_deploy/html/images/micromachines-15-01020-g001-550.jpg?1723207579)
Figure 1
Figure 1
<p>Workpiece model of the polycrystalline γ-TiAl alloy. (<b>a</b>) Crystal lattice structure diagram. (<b>b</b>) Sectional view of lattice structure.</p> Full article ">Figure 2
<p>Molecular dynamics simulation model of nano-indentation for the polycrystalline γ-TiAl alloy.</p> Full article ">Figure 3
<p>The load-time curve.</p> Full article ">Figure 4
<p>Distribution and evolution of defect structure in workpiece during stress relaxation. (<b>a</b>) Time 53 ps, (<b>b</b>) time 70 ps, (<b>c</b>) time 100 ps, (<b>d</b>) time 110 ps, (<b>e</b>) time 130 ps, and (<b>f</b>) time 150 ps.</p> Full article ">Figure 4 Cont.
<p>Distribution and evolution of defect structure in workpiece during stress relaxation. (<b>a</b>) Time 53 ps, (<b>b</b>) time 70 ps, (<b>c</b>) time 100 ps, (<b>d</b>) time 110 ps, (<b>e</b>) time 130 ps, and (<b>f</b>) time 150 ps.</p> Full article ">Figure 5
<p>Microstructure evolution of G4 grains during stress relaxation. (<b>a</b>) Time 53 ps, (<b>b</b>) time 70 ps, (<b>c</b>) time 100 ps, (<b>d</b>) time 105 ps, (<b>e</b>) time 110 ps, and (<b>f</b>) time 150 ps.</p> Full article ">Figure 6
<p>The equivalent stress distribution in the workpiece during stress relaxation. (<b>a</b>) Time 53 ps, (<b>b</b>) time 70 ps, (<b>c</b>) time 100 ps, (<b>d</b>) time 105 ps, (<b>e</b>) time 110 ps, and (<b>f</b>) time 150 ps.</p> Full article ">Figure 7
<p>Ti-Al system according to the current fraction assessment.</p> Full article ">Figure 8
<p>The EDS energy spectrum analysis.</p> Full article ">Figure 9
<p>Test workpiece.</p> Full article ">Figure 10
<p>FT-MTA03 micromechanical testing and assembly system.</p> Full article ">Figure 11
<p>FT-S200000 micro-force sensor.</p> Full article ">Figure 12
<p>The load-time curve. (<b>a</b>) Load is 10 mN, (<b>b</b>) load is 15 mN, (<b>c</b>) load is 20 mN, (<b>d</b>) load is 25 mN, and (<b>e</b>) load is 30 mN.</p> Full article ">Figure 13
<p>The load difference—load relationship diagram.</p> Full article ">
<p>Workpiece model of the polycrystalline γ-TiAl alloy. (<b>a</b>) Crystal lattice structure diagram. (<b>b</b>) Sectional view of lattice structure.</p> Full article ">Figure 2
<p>Molecular dynamics simulation model of nano-indentation for the polycrystalline γ-TiAl alloy.</p> Full article ">Figure 3
<p>The load-time curve.</p> Full article ">Figure 4
<p>Distribution and evolution of defect structure in workpiece during stress relaxation. (<b>a</b>) Time 53 ps, (<b>b</b>) time 70 ps, (<b>c</b>) time 100 ps, (<b>d</b>) time 110 ps, (<b>e</b>) time 130 ps, and (<b>f</b>) time 150 ps.</p> Full article ">Figure 4 Cont.
<p>Distribution and evolution of defect structure in workpiece during stress relaxation. (<b>a</b>) Time 53 ps, (<b>b</b>) time 70 ps, (<b>c</b>) time 100 ps, (<b>d</b>) time 110 ps, (<b>e</b>) time 130 ps, and (<b>f</b>) time 150 ps.</p> Full article ">Figure 5
<p>Microstructure evolution of G4 grains during stress relaxation. (<b>a</b>) Time 53 ps, (<b>b</b>) time 70 ps, (<b>c</b>) time 100 ps, (<b>d</b>) time 105 ps, (<b>e</b>) time 110 ps, and (<b>f</b>) time 150 ps.</p> Full article ">Figure 6
<p>The equivalent stress distribution in the workpiece during stress relaxation. (<b>a</b>) Time 53 ps, (<b>b</b>) time 70 ps, (<b>c</b>) time 100 ps, (<b>d</b>) time 105 ps, (<b>e</b>) time 110 ps, and (<b>f</b>) time 150 ps.</p> Full article ">Figure 7
<p>Ti-Al system according to the current fraction assessment.</p> Full article ">Figure 8
<p>The EDS energy spectrum analysis.</p> Full article ">Figure 9
<p>Test workpiece.</p> Full article ">Figure 10
<p>FT-MTA03 micromechanical testing and assembly system.</p> Full article ">Figure 11
<p>FT-S200000 micro-force sensor.</p> Full article ">Figure 12
<p>The load-time curve. (<b>a</b>) Load is 10 mN, (<b>b</b>) load is 15 mN, (<b>c</b>) load is 20 mN, (<b>d</b>) load is 25 mN, and (<b>e</b>) load is 30 mN.</p> Full article ">Figure 13
<p>The load difference—load relationship diagram.</p> Full article ">
Open AccessArticle
A 640 nA IQ Output-Capacitor-Less Low Dropout (LDO) Regulator with Sub-Threshold Slew-Rate Enhancement for Narrow Band Internet of Things (NB-IoT) Applications
by
Yuxin Zhang, Jueping Cai, Jizhang Chen and Yixin Yin
Micromachines 2024, 15(8), 1019; https://doi.org/10.3390/mi15081019 - 9 Aug 2024
Abstract
An ultra-low quiescent current output-capacitor-less low dropout (OCL-LDO) regulator for power-sensitive applications is proposed in this paper. To improve the gain of the OCL-LDO feedback loop, the error amplifier employs a combination of a cross-coupled input stage for boosting the equivalent input transconductance
[...] Read more.
An ultra-low quiescent current output-capacitor-less low dropout (OCL-LDO) regulator for power-sensitive applications is proposed in this paper. To improve the gain of the OCL-LDO feedback loop, the error amplifier employs a combination of a cross-coupled input stage for boosting the equivalent input transconductance and a negative resistance technique to improve the gain. Meanwhile, in order to address the issue of transient response of the ultra-low quiescent current OCL-LDO, a sub-threshold slew-rate enhancement circuit is proposed in this paper, which consists of a transient signal input stage and a slew-rate current increase branch. The proposed OCL-LDO is fabricated in a 0.18 m CMOS process with an effective area of 0.049 mm2. According to the measurement results, the proposed OCL-LDO has a maximum load current of 100 mA and a minimum quiescent current of 640 nA at an input voltage of 1.2 V and an output voltage of 1 V. The overshoot and undershoot voltages are 197 mV and 201 mV, respectively, and the PSR of the OCL-LDO is −72.4 dB at 1 kHz when the load current is 100 A. In addition, the OCL-LDO has a load regulation of 7.6 V/mA and a line regulation of 0.87 mV/V.
Full article
(This article belongs to the Section D1: Semiconductor Devices)
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![](https://pub.mdpi-res.com/micromachines/micromachines-15-01019/article_deploy/html/images/micromachines-15-01019-g001-550.jpg?1723202903)
Figure 1
Figure 1
<p>The classic composition of an NB-IoT application.</p> Full article ">Figure 2
<p>Structure of proposed OCL-LDO.</p> Full article ">Figure 3
<p>Small-signal model of proposed OCL-LDO without slew-rate enhancement circuit.</p> Full article ">Figure 4
<p>Small-signal model of proposed OCL-LDO with slew-rate enhancement circuit.</p> Full article ">Figure 5
<p>Simulated loop gain of proposed OCL-LDO under different load currents when <math display="inline"><semantics> <msub> <mi>C</mi> <mi>L</mi> </msub> </semantics></math> is 100 pF and temperature is room temperature.</p> Full article ">Figure 6
<p>Simulated loop phase of proposed OCL-LDO under different load currents when <math display="inline"><semantics> <msub> <mi>C</mi> <mi>L</mi> </msub> </semantics></math> is 100 pF and temperature is room temperature.</p> Full article ">Figure 7
<p>Simulated phase margin vs. load current.</p> Full article ">Figure 8
<p>Overall circuit of proposed OCL-LDO.</p> Full article ">Figure 9
<p>Loop gain of proposed utilizes different error amplifier.</p> Full article ">Figure 10
<p><math display="inline"><semantics> <msub> <mi>R</mi> <mrow> <mi>o</mi> <mi>n</mi> </mrow> </msub> </semantics></math> of GSC PMOS when L = 0.2 <math display="inline"><semantics> <mo>μ</mo> </semantics></math>m.</p> Full article ">Figure 11
<p>Load current changes between 100 <math display="inline"><semantics> <mo>μ</mo> </semantics></math>A and 100 mA in 500 ns.</p> Full article ">Figure 12
<p>Simulation result of load transient response as <math display="inline"><semantics> <msub> <mi>V</mi> <mi>IN</mi> </msub> </semantics></math> = 1.2 V and <math display="inline"><semantics> <msub> <mi>V</mi> <mi>OUT</mi> </msub> </semantics></math> = 1 V.</p> Full article ">Figure 13
<p>Simulation results of recovery time vs. resistor value.</p> Full article ">Figure 14
<p>Photomicrograph of proposed OCL-LDO.</p> Full article ">Figure 15
<p>Schematic diagram of OCL-LDO measurements.</p> Full article ">Figure 16
<p>PCB board for the measurement of OCL-LDOs.</p> Full article ">Figure 17
<p>Load transient response as <math display="inline"><semantics> <msub> <mi>V</mi> <mi>IN</mi> </msub> </semantics></math> = 1.2 V and <math display="inline"><semantics> <msub> <mi>V</mi> <mi>OUT</mi> </msub> </semantics></math> = 1 V.</p> Full article ">Figure 18
<p>Line transient response as <math display="inline"><semantics> <msub> <mi>I</mi> <mi>Load</mi> </msub> </semantics></math> = 10 <math display="inline"><semantics> <mo>μ</mo> </semantics></math>A.</p> Full article ">Figure 19
<p>Measured line regulation of the proposed OCL-LDO under different loads.</p> Full article ">Figure 20
<p>Measured load regulation of proposed OCL-LDO under different supply voltages.</p> Full article ">Figure 21
<p>Measured PSR of the proposed OCL-LDO.</p> Full article ">Figure 22
<p>Measurement results of quiescent current and current efficiency.</p> Full article ">
<p>The classic composition of an NB-IoT application.</p> Full article ">Figure 2
<p>Structure of proposed OCL-LDO.</p> Full article ">Figure 3
<p>Small-signal model of proposed OCL-LDO without slew-rate enhancement circuit.</p> Full article ">Figure 4
<p>Small-signal model of proposed OCL-LDO with slew-rate enhancement circuit.</p> Full article ">Figure 5
<p>Simulated loop gain of proposed OCL-LDO under different load currents when <math display="inline"><semantics> <msub> <mi>C</mi> <mi>L</mi> </msub> </semantics></math> is 100 pF and temperature is room temperature.</p> Full article ">Figure 6
<p>Simulated loop phase of proposed OCL-LDO under different load currents when <math display="inline"><semantics> <msub> <mi>C</mi> <mi>L</mi> </msub> </semantics></math> is 100 pF and temperature is room temperature.</p> Full article ">Figure 7
<p>Simulated phase margin vs. load current.</p> Full article ">Figure 8
<p>Overall circuit of proposed OCL-LDO.</p> Full article ">Figure 9
<p>Loop gain of proposed utilizes different error amplifier.</p> Full article ">Figure 10
<p><math display="inline"><semantics> <msub> <mi>R</mi> <mrow> <mi>o</mi> <mi>n</mi> </mrow> </msub> </semantics></math> of GSC PMOS when L = 0.2 <math display="inline"><semantics> <mo>μ</mo> </semantics></math>m.</p> Full article ">Figure 11
<p>Load current changes between 100 <math display="inline"><semantics> <mo>μ</mo> </semantics></math>A and 100 mA in 500 ns.</p> Full article ">Figure 12
<p>Simulation result of load transient response as <math display="inline"><semantics> <msub> <mi>V</mi> <mi>IN</mi> </msub> </semantics></math> = 1.2 V and <math display="inline"><semantics> <msub> <mi>V</mi> <mi>OUT</mi> </msub> </semantics></math> = 1 V.</p> Full article ">Figure 13
<p>Simulation results of recovery time vs. resistor value.</p> Full article ">Figure 14
<p>Photomicrograph of proposed OCL-LDO.</p> Full article ">Figure 15
<p>Schematic diagram of OCL-LDO measurements.</p> Full article ">Figure 16
<p>PCB board for the measurement of OCL-LDOs.</p> Full article ">Figure 17
<p>Load transient response as <math display="inline"><semantics> <msub> <mi>V</mi> <mi>IN</mi> </msub> </semantics></math> = 1.2 V and <math display="inline"><semantics> <msub> <mi>V</mi> <mi>OUT</mi> </msub> </semantics></math> = 1 V.</p> Full article ">Figure 18
<p>Line transient response as <math display="inline"><semantics> <msub> <mi>I</mi> <mi>Load</mi> </msub> </semantics></math> = 10 <math display="inline"><semantics> <mo>μ</mo> </semantics></math>A.</p> Full article ">Figure 19
<p>Measured line regulation of the proposed OCL-LDO under different loads.</p> Full article ">Figure 20
<p>Measured load regulation of proposed OCL-LDO under different supply voltages.</p> Full article ">Figure 21
<p>Measured PSR of the proposed OCL-LDO.</p> Full article ">Figure 22
<p>Measurement results of quiescent current and current efficiency.</p> Full article ">
Open AccessArticle
Investigation of Piezoelectric Properties in Ca-Doped PbBa(Zr,Ti)O3 (PBZT) Ceramics
by
Jolanta Makowska, Marian Pawełczyk, Andrzej Soszyński, Tomasz Pikula and Małgorzata Adamczyk-Habrajska
Micromachines 2024, 15(8), 1018; https://doi.org/10.3390/mi15081018 - 9 Aug 2024
Abstract
The perovskite-structured materials for x = 1 and 2 at.% were synthesized using the conventional mixed-oxide method and carbonates. Microstructural analysis,
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The perovskite-structured materials for x = 1 and 2 at.% were synthesized using the conventional mixed-oxide method and carbonates. Microstructural analysis, performed using a scanning electron microscope, revealed rounded grains with relatively inhomogeneous sizes and distinct grain boundaries. X-ray diffraction confirmed that the materials exhibit a rhombohedral structure with an R3c space group at room temperature. Piezoelectric resonance measurements were conducted to determine the piezoelectric and elastic properties of the samples. The results indicated that a small amount of calcium doping significantly enhanced the piezoelectric coefficient d31. The calcium-doped ceramics exhibited higher electrical permittivity across the entire temperature range compared to the pure material, as well as a significant value of remanent polarization. These findings indicate that the performance parameters of the base material have been significantly improved, making these ceramics promising candidates for various applications.
Full article
(This article belongs to the Special Issue Piezoelectric Materials, Devices and Systems)
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![](https://pub.mdpi-res.com/micromachines/micromachines-15-01018/article_deploy/html/images/micromachines-15-01018-g001-550.jpg?1723174792)
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<p>Microstructure of PBZT ceramics modified by 1 and 2 at.% of Ca.</p> Full article ">Figure 2
<p>Exemplary EDS spectrum on the PBZT ceramics modified by 2 at.% of Ca.</p> Full article ">Figure 3
<p>X-ray diffraction pattern (XRD) of calcium-doped PBZT ceramics.</p> Full article ">Figure 4
<p>Temperature dependencies of the dielectric constant measured on heating at various frequencies of measuring field for calcium-modified ceramics (<b>a</b>) 1 at.% (<b>b</b>) 2 at.%.</p> Full article ">Figure 5
<p>Temperature dependencies of the loss factor measured on heating at various frequencies of measuring field for calcium-modified ceramics (<b>a</b>) 1 at.% (<b>b</b>) 2 at.%.</p> Full article ">Figure 6
<p>The remanent polarization of calcium ions modified PBZT 25/70/30 ceramics as a function of temperature, obtained from hysteresis loop measurements.</p> Full article ">Figure 7
<p>Frequency dependencies of (<b>a</b>,<b>c</b>) the modulus |Y | of the complex admittance <span class="html-italic">Y = G + iB</span> and (<b>b</b>,<b>d</b>) the modulus |Z| of the complex impedance <span class="html-italic">Z = R + iX</span>.</p> Full article ">
<p>Microstructure of PBZT ceramics modified by 1 and 2 at.% of Ca.</p> Full article ">Figure 2
<p>Exemplary EDS spectrum on the PBZT ceramics modified by 2 at.% of Ca.</p> Full article ">Figure 3
<p>X-ray diffraction pattern (XRD) of calcium-doped PBZT ceramics.</p> Full article ">Figure 4
<p>Temperature dependencies of the dielectric constant measured on heating at various frequencies of measuring field for calcium-modified ceramics (<b>a</b>) 1 at.% (<b>b</b>) 2 at.%.</p> Full article ">Figure 5
<p>Temperature dependencies of the loss factor measured on heating at various frequencies of measuring field for calcium-modified ceramics (<b>a</b>) 1 at.% (<b>b</b>) 2 at.%.</p> Full article ">Figure 6
<p>The remanent polarization of calcium ions modified PBZT 25/70/30 ceramics as a function of temperature, obtained from hysteresis loop measurements.</p> Full article ">Figure 7
<p>Frequency dependencies of (<b>a</b>,<b>c</b>) the modulus |Y | of the complex admittance <span class="html-italic">Y = G + iB</span> and (<b>b</b>,<b>d</b>) the modulus |Z| of the complex impedance <span class="html-italic">Z = R + iX</span>.</p> Full article ">
Open AccessArticle
A Large-Scan-Range Electrothermal Micromirror Integrated with Thermal Convection-Based Position Sensors
by
Anrun Ren, Yingtao Ding, Hengzhang Yang, Teng Pan, Ziyue Zhang and Huikai Xie
Micromachines 2024, 15(8), 1017; https://doi.org/10.3390/mi15081017 - 8 Aug 2024
Abstract
This paper presents the design, simulation, fabrication, and characterization of a novel large-scan-range electrothermal micromirror integrated with a pair of position sensors. Note that the micromirror and the sensors can be manufactured within a single MEMS process flow. Thanks to the precise control
[...] Read more.
This paper presents the design, simulation, fabrication, and characterization of a novel large-scan-range electrothermal micromirror integrated with a pair of position sensors. Note that the micromirror and the sensors can be manufactured within a single MEMS process flow. Thanks to the precise control of the fabrication of the grid-based large-size Al/SiO2 bimorph actuators, the maximum piston displacement and optical scan angle of the micromirror reach 370 μm and 36° at only 6 Vdc, respectively. Furthermore, the working principle of the sensors is deeply investigated, where the motion of the micromirror is reflected by monitoring the temperature variation-induced resistance change of the thermistors on the substrate during the synchronous movement of the mirror plate and the heaters. The results show that the full-range motion of the micromirror can be recognized by the sensors with sensitivities of 0.3 mV/μm in the piston displacement sensing and 2.1 mV/° in the tip-tilt sensing, respectively. The demonstrated large-scan-range micromirror that can be monitored by position sensors has a promising prospect for the MEMS Fourier transform spectrometers (FTS) systems.
Full article
(This article belongs to the Collection Optical MEMS: Design, Fabrication, Control, Modeling and Developments)
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![](https://pub.mdpi-res.com/micromachines/micromachines-15-01017/article_deploy/html/images/micromachines-15-01017-g001-550.jpg?1723098716)
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Figure 1
<p>Schematic diagrams of different position sensing methods: (<b>a</b>) capacitive sensing [<a href="#B13-micromachines-15-01017" class="html-bibr">13</a>]; (<b>b</b>) piezoresistive sensing [<a href="#B19-micromachines-15-01017" class="html-bibr">19</a>]; (<b>c</b>) optical sensing [<a href="#B21-micromachines-15-01017" class="html-bibr">21</a>]; (<b>d</b>) inductive eddy current sensing [<a href="#B26-micromachines-15-01017" class="html-bibr">26</a>]; (<b>e</b>) piezoelectric sensing [<a href="#B29-micromachines-15-01017" class="html-bibr">29</a>].</p> Full article ">Figure 2
<p>Schematic illustration of the electrothermal micromirror integrated with thermal convection-based position sensors.</p> Full article ">Figure 3
<p>Working principles of the position sensors; (<b>a</b>–<b>c</b>) piston sensing; (<b>d</b>–<b>f</b>) tip-tilt sensing.</p> Full article ">Figure 4
<p>Schematic diagrams of the Wheatstone bridge circuits: (<b>a</b>) piston sensing circuit. (<b>b</b>) tip-tilt sensing circuit.</p> Full article ">Figure 5
<p>Schematic diagrams of the proposed device and the key components: (<b>a</b>) top view of the device; (<b>b</b>) enlarged view of the bimorph actuator; (<b>c</b>) 3D structure of the bimorph; (<b>d</b>) enlarged view of the position sensor and the critical structural parameters.</p> Full article ">Figure 6
<p>Simulated temperature distributions of the position sensors during working at <span class="html-italic">T</span><sub>0</sub> = 293 K. (<b>a</b>,<b>b</b>) Piston sensing. (<b>c</b>,<b>d</b>) Tip-tilt sensing.</p> Full article ">Figure 7
<p>Extracted temperature curves along the indicated lines in <a href="#micromachines-15-01017-f006" class="html-fig">Figure 6</a>: (<b>a</b>) piston sensing; (<b>b</b>) tip-tilt sensing.</p> Full article ">Figure 8
<p>Temperature variations of the thermistors under different environment temperatures: (<b>a</b>) piston displacements; (<b>b</b>) optical scan angles.</p> Full article ">Figure 9
<p>Fabrication process of the large-scan-range electrothermal micromirror integrated with position sensors. (<b>a</b>) PECVD oxide deposition and etching. (<b>b</b>) PECVD oxide deposition. (<b>c</b>) Pt sputtering and lift-off. (<b>d</b>) PECVD oxide deposition and etching. (<b>e</b>) Al sputtering and etching. (<b>f</b>) Oxide etching. (<b>g</b>) Backside Si etching. (<b>h</b>) Backside box layer etching. (<b>i</b>) Frontside Si isotropic etching.</p> Full article ">Figure 10
<p>Images of the fabricated electrothermal micromirror integrated with position sensors: (<b>a</b>) the fabricated device after release; (<b>b</b>) the close-up view of the heater and the thermistor.</p> Full article ">Figure 11
<p>Measured resistance-temperature curve for the Pt resistor in the bimorph.</p> Full article ">Figure 12
<p>The quasi-static and dynamic responses of the micromirror: (<b>a</b>) piston displacement versus driving voltage; (<b>b</b>) optical angle versus driving voltage; (<b>c</b>) frequency response.</p> Full article ">Figure 13
<p>Quasi-static measurement results: (<b>a</b>) the output of the position sensor and calibrated piston displacement versus the driving voltage of two actuators; (<b>b</b>) the output of the position sensor and calibrated optical scan range versus the driving voltage of one actuator.</p> Full article ">
<p>Schematic diagrams of different position sensing methods: (<b>a</b>) capacitive sensing [<a href="#B13-micromachines-15-01017" class="html-bibr">13</a>]; (<b>b</b>) piezoresistive sensing [<a href="#B19-micromachines-15-01017" class="html-bibr">19</a>]; (<b>c</b>) optical sensing [<a href="#B21-micromachines-15-01017" class="html-bibr">21</a>]; (<b>d</b>) inductive eddy current sensing [<a href="#B26-micromachines-15-01017" class="html-bibr">26</a>]; (<b>e</b>) piezoelectric sensing [<a href="#B29-micromachines-15-01017" class="html-bibr">29</a>].</p> Full article ">Figure 2
<p>Schematic illustration of the electrothermal micromirror integrated with thermal convection-based position sensors.</p> Full article ">Figure 3
<p>Working principles of the position sensors; (<b>a</b>–<b>c</b>) piston sensing; (<b>d</b>–<b>f</b>) tip-tilt sensing.</p> Full article ">Figure 4
<p>Schematic diagrams of the Wheatstone bridge circuits: (<b>a</b>) piston sensing circuit. (<b>b</b>) tip-tilt sensing circuit.</p> Full article ">Figure 5
<p>Schematic diagrams of the proposed device and the key components: (<b>a</b>) top view of the device; (<b>b</b>) enlarged view of the bimorph actuator; (<b>c</b>) 3D structure of the bimorph; (<b>d</b>) enlarged view of the position sensor and the critical structural parameters.</p> Full article ">Figure 6
<p>Simulated temperature distributions of the position sensors during working at <span class="html-italic">T</span><sub>0</sub> = 293 K. (<b>a</b>,<b>b</b>) Piston sensing. (<b>c</b>,<b>d</b>) Tip-tilt sensing.</p> Full article ">Figure 7
<p>Extracted temperature curves along the indicated lines in <a href="#micromachines-15-01017-f006" class="html-fig">Figure 6</a>: (<b>a</b>) piston sensing; (<b>b</b>) tip-tilt sensing.</p> Full article ">Figure 8
<p>Temperature variations of the thermistors under different environment temperatures: (<b>a</b>) piston displacements; (<b>b</b>) optical scan angles.</p> Full article ">Figure 9
<p>Fabrication process of the large-scan-range electrothermal micromirror integrated with position sensors. (<b>a</b>) PECVD oxide deposition and etching. (<b>b</b>) PECVD oxide deposition. (<b>c</b>) Pt sputtering and lift-off. (<b>d</b>) PECVD oxide deposition and etching. (<b>e</b>) Al sputtering and etching. (<b>f</b>) Oxide etching. (<b>g</b>) Backside Si etching. (<b>h</b>) Backside box layer etching. (<b>i</b>) Frontside Si isotropic etching.</p> Full article ">Figure 10
<p>Images of the fabricated electrothermal micromirror integrated with position sensors: (<b>a</b>) the fabricated device after release; (<b>b</b>) the close-up view of the heater and the thermistor.</p> Full article ">Figure 11
<p>Measured resistance-temperature curve for the Pt resistor in the bimorph.</p> Full article ">Figure 12
<p>The quasi-static and dynamic responses of the micromirror: (<b>a</b>) piston displacement versus driving voltage; (<b>b</b>) optical angle versus driving voltage; (<b>c</b>) frequency response.</p> Full article ">Figure 13
<p>Quasi-static measurement results: (<b>a</b>) the output of the position sensor and calibrated piston displacement versus the driving voltage of two actuators; (<b>b</b>) the output of the position sensor and calibrated optical scan range versus the driving voltage of one actuator.</p> Full article ">
Open AccessArticle
Development of a Plate Linear Ultrasonic Motor Using the Power Flow Method
by
Yue Jian, Zhen Liu, Junfeng He, Wenjie Zhou and Huazhuo Liang
Micromachines 2024, 15(8), 1016; https://doi.org/10.3390/mi15081016 - 8 Aug 2024
Abstract
Linear ultrasonic motors can output large thrust stably in a narrow space. In this paper, a plate linear ultrasonic motor is studied. Firstly, the configuration and operating principle of the -type linear ultrasonic motor is illustrated. Then, two slotting schemes are put
[...] Read more.
Linear ultrasonic motors can output large thrust stably in a narrow space. In this paper, a plate linear ultrasonic motor is studied. Firstly, the configuration and operating principle of the -type linear ultrasonic motor is illustrated. Then, two slotting schemes are put forward for the stator to enlarge the amplitude of the driving foot and improve the output performance of motor. After that, a novel optimization method based on the power flow method is suggested to describe the energy flow of stator, so as to estimate the slotting schemes. Finally, the prototypes are manufactured and tested. The experimental results show that the output performance of both new motors are excellent. The maximum output thrust of the arc slotted motor is 76 N/94 N, and the corresponding maximum no-load speed is 283 mm/s/213 mm/s, while the maximum output thrust of V-slotted motor reaches 90 N/120 N, and the maximum no-load speed reaches 223 mm/s/368 mm/s.
Full article
(This article belongs to the Topic Advances in Piezoelectric/Ultrasonic Sensors and Actuators-2nd Volume)
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![](https://pub.mdpi-res.com/micromachines/micromachines-15-01016/article_deploy/html/images/micromachines-15-01016-g001-550.jpg?1723098203)
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<p>Specific view of the stator.</p> Full article ">Figure 2
<p>The integrated structure of the motor.</p> Full article ">Figure 3
<p>The working principle of the <math display="inline"><semantics> <mo>Π</mo> </semantics></math>-type motor for (<b>a</b>) inward motion and (<b>b</b>) outward motion.</p> Full article ">Figure 4
<p>Amplitude of the driving foot of the original motor for (<b>a</b>) inward motion and (<b>b</b>) outward motion.</p> Full article ">Figure 5
<p>Head block of arc slotted stator.</p> Full article ">Figure 6
<p>Amplitude of the driving foot of the arc slotted motor (<b>a</b>) for (<b>b</b>) inward motion and (<b>c</b>) outward motion.</p> Full article ">Figure 7
<p>Head block of V-shaped slotted stator.</p> Full article ">Figure 8
<p>Amplitude of the driving foot of the V-shaped slotted motor(<b>a</b>) for (<b>b</b>) inward motion and (<b>c</b>) outward motion.</p> Full article ">Figure 9
<p>Visualization of the structural intensity of (<b>a</b>) the original motor for inward motion, (<b>b</b>) the original motor for outward motion, (<b>c</b>) the arc slotted motor for inward motion, (<b>d</b>) the arc slotted motor for outward motion, (<b>e</b>) the V-shaped slotted motor for inward motion, and (<b>f</b>) the V-shaped slotted motor for outward motion.</p> Full article ">Figure 10
<p>Prototypes for (<b>a</b>) the arc slotted stator and (<b>b</b>) the V-shaped slotted stator.</p> Full article ">Figure 11
<p>Experimental setup.</p> Full article ">Figure 12
<p>Relation between output velocity and excitation frequency of the arc slotted stator for inward motion (<b>a</b>) and outward motion (<b>b</b>) at various preload levels.</p> Full article ">Figure 13
<p>Relation between output thrust and excitation frequency of the arc slotted stator for inward motion (<b>a</b>) and outward motion (<b>b</b>) at various preload levels.</p> Full article ">Figure 14
<p>Relation between output velocity and excitation frequency of the V-shaped slotted stator for inward motion (<b>a</b>) and outward motion (<b>b</b>) at various preload levels.</p> Full article ">Figure 15
<p>Relation between output thrust and excitation frequency of the V-shaped slotted stator for inward motion (<b>a</b>) and outward motion (<b>b</b>) at various preload levels.</p> Full article ">
<p>Specific view of the stator.</p> Full article ">Figure 2
<p>The integrated structure of the motor.</p> Full article ">Figure 3
<p>The working principle of the <math display="inline"><semantics> <mo>Π</mo> </semantics></math>-type motor for (<b>a</b>) inward motion and (<b>b</b>) outward motion.</p> Full article ">Figure 4
<p>Amplitude of the driving foot of the original motor for (<b>a</b>) inward motion and (<b>b</b>) outward motion.</p> Full article ">Figure 5
<p>Head block of arc slotted stator.</p> Full article ">Figure 6
<p>Amplitude of the driving foot of the arc slotted motor (<b>a</b>) for (<b>b</b>) inward motion and (<b>c</b>) outward motion.</p> Full article ">Figure 7
<p>Head block of V-shaped slotted stator.</p> Full article ">Figure 8
<p>Amplitude of the driving foot of the V-shaped slotted motor(<b>a</b>) for (<b>b</b>) inward motion and (<b>c</b>) outward motion.</p> Full article ">Figure 9
<p>Visualization of the structural intensity of (<b>a</b>) the original motor for inward motion, (<b>b</b>) the original motor for outward motion, (<b>c</b>) the arc slotted motor for inward motion, (<b>d</b>) the arc slotted motor for outward motion, (<b>e</b>) the V-shaped slotted motor for inward motion, and (<b>f</b>) the V-shaped slotted motor for outward motion.</p> Full article ">Figure 10
<p>Prototypes for (<b>a</b>) the arc slotted stator and (<b>b</b>) the V-shaped slotted stator.</p> Full article ">Figure 11
<p>Experimental setup.</p> Full article ">Figure 12
<p>Relation between output velocity and excitation frequency of the arc slotted stator for inward motion (<b>a</b>) and outward motion (<b>b</b>) at various preload levels.</p> Full article ">Figure 13
<p>Relation between output thrust and excitation frequency of the arc slotted stator for inward motion (<b>a</b>) and outward motion (<b>b</b>) at various preload levels.</p> Full article ">Figure 14
<p>Relation between output velocity and excitation frequency of the V-shaped slotted stator for inward motion (<b>a</b>) and outward motion (<b>b</b>) at various preload levels.</p> Full article ">Figure 15
<p>Relation between output thrust and excitation frequency of the V-shaped slotted stator for inward motion (<b>a</b>) and outward motion (<b>b</b>) at various preload levels.</p> Full article ">
Open AccessArticle
Series/Parallel Switching for Increasing Power Extraction from Thermoelectric Power Generators
by
Shingo Terashima, Ryuji Sorimachi and Eiji Iwase
Micromachines 2024, 15(8), 1015; https://doi.org/10.3390/mi15081015 - 7 Aug 2024
Abstract
We propose a method for increasing power extraction from a thermoelectric generator (TEG) by switching between series/parallel circuit configurations of thermoelectric elements, which can adjust the internal impedance of the TEG. The power characteristics of the TEG can be adjusted to the load
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We propose a method for increasing power extraction from a thermoelectric generator (TEG) by switching between series/parallel circuit configurations of thermoelectric elements, which can adjust the internal impedance of the TEG. The power characteristics of the TEG can be adjusted to the load characteristics of the connected device and the relevant ambient temperature. In this paper, we analyzed the change in the TEG characteristics with the series/parallel switching function. We evaluated the power supply to the connected devices at different ambient temperatures and different series/parallel configurations and confirmed that the extracted power could be increased. By theoretically analyzing the circuit configuration of the thermoelectric devices, the switching required to improve the power extraction, and the temperature difference at which switching occurred, we devised a design method for a TEG with circuit switching in order to increase power extraction with any device. We demonstrated the configuration of switching by using a system in which a TEG supplied power to an external wireless transmitter circuit. In this system, the optimal configuration differed at temperature differences of 3.0 K and 4.0 K. At a temperature difference of 3.0 K, the 2-series/1-parallel configuration provided 10% more power to the external circuit than the 1-series/2-parallel configuration. On the other hand, at the temperature difference of 4.0 K, the 1-series/2-parallel configuration provided 23% more power than the 2-series/1-parallel configuration.
Full article
(This article belongs to the Special Issue Selected Papers from the 14th Symposium on Micro-Nano Science and Technology on Micromachines)
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![](https://pub.mdpi-res.com/micromachines/micromachines-15-01015/article_deploy/html/images/micromachines-15-01015-g001-550.jpg?1723021685)
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<p>Schematics of the calculated series/parallel configurations and output and load characteristics: (<b>a</b>) A schematic of the <span class="html-italic">m</span>-series/4-parallel, 2<span class="html-italic">m</span>-series/2-parallel, and 4<span class="html-italic">m</span>-series/1-parallel configurations of thermoelectric elements. (<b>b</b>) The relationship between the load characteristics of the external circuit when the resistance of the output circuit changes depending on the temperature difference of the thermoelectric elements and the power supply characteristics.</p> Full article ">Figure 2
<p>Schematics of area division regarding maximum extracted power: (<b>a</b>) Boundary line that separates the regions where certain circuit configuration exhibits maximum extracted power. Red, blue, and green in the figure indicate the parallel numbers <span class="html-italic">l</span><sub>1</sub>, <span class="html-italic">l</span><sub>2</sub>, and <span class="html-italic">l</span><sub>3</sub>, respectively. (<b>b</b>) Relationship between load characteristics of connected external circuits and each area.</p> Full article ">Figure 3
<p>(<b>a</b>) Schematics of power supply circuits, (<b>b</b>) photograph of fabricated power supply circuit, (<b>c</b>) schematics of setup for temperature and power characteristic measurements, (<b>d</b>) measured power supply characteristics and load characteristics of external circuit, and (<b>e</b>) first charging time and charging time after capacitor becomes stable.</p> Full article ">Figure 3 Cont.
<p>(<b>a</b>) Schematics of power supply circuits, (<b>b</b>) photograph of fabricated power supply circuit, (<b>c</b>) schematics of setup for temperature and power characteristic measurements, (<b>d</b>) measured power supply characteristics and load characteristics of external circuit, and (<b>e</b>) first charging time and charging time after capacitor becomes stable.</p> Full article ">
<p>Schematics of the calculated series/parallel configurations and output and load characteristics: (<b>a</b>) A schematic of the <span class="html-italic">m</span>-series/4-parallel, 2<span class="html-italic">m</span>-series/2-parallel, and 4<span class="html-italic">m</span>-series/1-parallel configurations of thermoelectric elements. (<b>b</b>) The relationship between the load characteristics of the external circuit when the resistance of the output circuit changes depending on the temperature difference of the thermoelectric elements and the power supply characteristics.</p> Full article ">Figure 2
<p>Schematics of area division regarding maximum extracted power: (<b>a</b>) Boundary line that separates the regions where certain circuit configuration exhibits maximum extracted power. Red, blue, and green in the figure indicate the parallel numbers <span class="html-italic">l</span><sub>1</sub>, <span class="html-italic">l</span><sub>2</sub>, and <span class="html-italic">l</span><sub>3</sub>, respectively. (<b>b</b>) Relationship between load characteristics of connected external circuits and each area.</p> Full article ">Figure 3
<p>(<b>a</b>) Schematics of power supply circuits, (<b>b</b>) photograph of fabricated power supply circuit, (<b>c</b>) schematics of setup for temperature and power characteristic measurements, (<b>d</b>) measured power supply characteristics and load characteristics of external circuit, and (<b>e</b>) first charging time and charging time after capacitor becomes stable.</p> Full article ">Figure 3 Cont.
<p>(<b>a</b>) Schematics of power supply circuits, (<b>b</b>) photograph of fabricated power supply circuit, (<b>c</b>) schematics of setup for temperature and power characteristic measurements, (<b>d</b>) measured power supply characteristics and load characteristics of external circuit, and (<b>e</b>) first charging time and charging time after capacitor becomes stable.</p> Full article ">
Open AccessArticle
The Design of a Multifunctional Coding Transmitarray with Independent Manipulation of the Polarization States
by
Shunlan Zhang, Weiping Cao, Tiesheng Wu, Jiao Wang and Ying Wei
Micromachines 2024, 15(8), 1014; https://doi.org/10.3390/mi15081014 - 7 Aug 2024
Abstract
Manipulating orthogonally polarized waves independently in a single metasurface is pivotal. However, independently controlling the phase shifts of orthogonally polarized waves is difficult, especially in the same frequency bands. Here, we propose a receiver-phase shift-transmitter transmitarray with independent control of arbitrary polarization states
[...] Read more.
Manipulating orthogonally polarized waves independently in a single metasurface is pivotal. However, independently controlling the phase shifts of orthogonally polarized waves is difficult, especially in the same frequency bands. Here, we propose a receiver-phase shift-transmitter transmitarray with independent control of arbitrary polarization states in the same frequency bands, in which transmission rates reach more than 90% in the frequency bands 4.2~4.9 GHz and 5.3~5.5 GHz. By introducing a phase-regulation structure to each element, phases covering for different polarized incident waves can be independently controlled by different geometric parameters, and two-bit coding phases can be obtained. The design principle based on the two-port network’s scattering matrix has been analyzed. To verify the independent tuning abilities of the proposed transmitarray for different polarization incidences in the same frequency bands, a multifunctional receive-phase shift-radiation coding transmitarray (RPRCT), which is composed of elements, with functions of anomalous refraction (for example, orbital angular momentum wave) and focusing transmission for different polarized incident waves was simulated and measured. The measured results agree reasonably well with the simulated ones. Our findings provide a simple method for obtaining a multifunctional metasurface with orthogonal polarization in the same frequency bands, which greatly improves the capacity and spectral efficiency of communication channels.
Full article
(This article belongs to the Section A:Physics)
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![](https://pub.mdpi-res.com/micromachines/micromachines-15-01014/article_deploy/html/images/micromachines-15-01014-g001-550.jpg?1723078626)
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<p>The multifunctional schematic diagram of the suggested RPRCT working with orthogonally polarized waves from top to bottom.</p> Full article ">Figure 2
<p>The geometry of the suggested transmission element. (<b>a</b>) The 3-D view perspective. (<b>b</b>) The top patch and its feed points. (<b>c</b>) The first ground layer. (<b>d</b>) The middle layer of the stripline. (<b>e</b>) The second ground layer. (<b>f</b>) The bottom patch and its feed points.</p> Full article ">Figure 3
<p>Transmission characterization for the x-/y-polarization incidence. (<b>a</b>) Magnitudes. (<b>b</b>) PCRs.</p> Full article ">Figure 4
<p>Transmission characteristics versus frequency for four kinds of coding particles. (<b>a</b>) Phases. (<b>b</b>) The transmission and reflection magnitudes.</p> Full article ">Figure 5
<p>Transmission analysis diagram. (<b>a</b>) Middle layer structure, (<b>b</b>) reflection and transmission coefficients.</p> Full article ">Figure 6
<p>The structure of the middle stripline: (<b>a</b>) side view and (<b>b</b>) interior structure.</p> Full article ">Figure 7
<p>Transmission performance of the middle stripline: (<b>a</b>) transmission phases with different l and (<b>b</b>) magnitudes of S11 with l = 75 mm.</p> Full article ">Figure 8
<p>The calculated desired phase profile of the metasurface for a vortex beam under the x incidence: (<b>a</b>)<math display="inline"><semantics> <mrow> <mtext> </mtext> <mi>l</mi> <msub> <mrow> <mi>φ</mi> </mrow> <mrow> <mi>m</mi> <mi>n</mi> </mrow> </msub> </mrow> </semantics></math>, and (<b>b</b>) <math display="inline"><semantics> <mrow> <mi>l</mi> <msub> <mrow> <mi>φ</mi> </mrow> <mrow> <mi>m</mi> <mi>n</mi> </mrow> </msub> <mo>−</mo> <msub> <mrow> <mi>k</mi> </mrow> <mrow> <mn>0</mn> </mrow> </msub> <mfenced open="|" close="|" separators="|"> <mrow> <msub> <mrow> <mover accent="true"> <mrow> <mi mathvariant="bold-italic">r</mi> </mrow> <mo>→</mo> </mover> </mrow> <mrow> <mi mathvariant="bold-italic">m</mi> <mi mathvariant="bold-italic">n</mi> </mrow> </msub> <mo>−</mo> <msub> <mrow> <mover accent="true"> <mrow> <mi mathvariant="bold-italic">r</mi> </mrow> <mo>→</mo> </mover> </mrow> <mrow> <mi mathvariant="bold-italic">f</mi> </mrow> </msub> </mrow> </mfenced> </mrow> </semantics></math>.</p> Full article ">Figure 9
<p>The calculated desired phase profile of the metasurface for bi-focal spots under the y incidence.</p> Full article ">Figure 10
<p>Magnitudes and phases of simulated transmission near electric fields at <math display="inline"><semantics> <mrow> <mi>z</mi> <mo>=</mo> <mo>−</mo> <mn>40</mn> <mtext> </mtext> <mi>mm</mi> </mrow> </semantics></math> because of the x incoming waves at 4.75 GHz for mode <span class="html-italic">l</span> = 1 from top to bottom: (<b>a</b>) magnitudes and (<b>b</b>) phases.</p> Full article ">Figure 11
<p>Simulated transmission near electric field: magnitude for bi-focal spots at z = −31.58 mm.</p> Full article ">Figure 12
<p>Fabricated prototype. (<b>a</b>) The top, (<b>b</b>) the bottom.</p> Full article ">Figure 13
<p>Experimental setup and schematic diagram.</p> Full article ">Figure 14
<p>Experimental normalized E-field distributions for the x-polarized waves from top to bottom: (<b>a</b>) magnitudes and (<b>b</b>) phases.</p> Full article ">Figure 15
<p>Experimental measurement of OAM E-field distributions for the y-polarized waves from bottom to top: (<b>a</b>) magnitudes and (<b>b</b>) phases.</p> Full article ">
<p>The multifunctional schematic diagram of the suggested RPRCT working with orthogonally polarized waves from top to bottom.</p> Full article ">Figure 2
<p>The geometry of the suggested transmission element. (<b>a</b>) The 3-D view perspective. (<b>b</b>) The top patch and its feed points. (<b>c</b>) The first ground layer. (<b>d</b>) The middle layer of the stripline. (<b>e</b>) The second ground layer. (<b>f</b>) The bottom patch and its feed points.</p> Full article ">Figure 3
<p>Transmission characterization for the x-/y-polarization incidence. (<b>a</b>) Magnitudes. (<b>b</b>) PCRs.</p> Full article ">Figure 4
<p>Transmission characteristics versus frequency for four kinds of coding particles. (<b>a</b>) Phases. (<b>b</b>) The transmission and reflection magnitudes.</p> Full article ">Figure 5
<p>Transmission analysis diagram. (<b>a</b>) Middle layer structure, (<b>b</b>) reflection and transmission coefficients.</p> Full article ">Figure 6
<p>The structure of the middle stripline: (<b>a</b>) side view and (<b>b</b>) interior structure.</p> Full article ">Figure 7
<p>Transmission performance of the middle stripline: (<b>a</b>) transmission phases with different l and (<b>b</b>) magnitudes of S11 with l = 75 mm.</p> Full article ">Figure 8
<p>The calculated desired phase profile of the metasurface for a vortex beam under the x incidence: (<b>a</b>)<math display="inline"><semantics> <mrow> <mtext> </mtext> <mi>l</mi> <msub> <mrow> <mi>φ</mi> </mrow> <mrow> <mi>m</mi> <mi>n</mi> </mrow> </msub> </mrow> </semantics></math>, and (<b>b</b>) <math display="inline"><semantics> <mrow> <mi>l</mi> <msub> <mrow> <mi>φ</mi> </mrow> <mrow> <mi>m</mi> <mi>n</mi> </mrow> </msub> <mo>−</mo> <msub> <mrow> <mi>k</mi> </mrow> <mrow> <mn>0</mn> </mrow> </msub> <mfenced open="|" close="|" separators="|"> <mrow> <msub> <mrow> <mover accent="true"> <mrow> <mi mathvariant="bold-italic">r</mi> </mrow> <mo>→</mo> </mover> </mrow> <mrow> <mi mathvariant="bold-italic">m</mi> <mi mathvariant="bold-italic">n</mi> </mrow> </msub> <mo>−</mo> <msub> <mrow> <mover accent="true"> <mrow> <mi mathvariant="bold-italic">r</mi> </mrow> <mo>→</mo> </mover> </mrow> <mrow> <mi mathvariant="bold-italic">f</mi> </mrow> </msub> </mrow> </mfenced> </mrow> </semantics></math>.</p> Full article ">Figure 9
<p>The calculated desired phase profile of the metasurface for bi-focal spots under the y incidence.</p> Full article ">Figure 10
<p>Magnitudes and phases of simulated transmission near electric fields at <math display="inline"><semantics> <mrow> <mi>z</mi> <mo>=</mo> <mo>−</mo> <mn>40</mn> <mtext> </mtext> <mi>mm</mi> </mrow> </semantics></math> because of the x incoming waves at 4.75 GHz for mode <span class="html-italic">l</span> = 1 from top to bottom: (<b>a</b>) magnitudes and (<b>b</b>) phases.</p> Full article ">Figure 11
<p>Simulated transmission near electric field: magnitude for bi-focal spots at z = −31.58 mm.</p> Full article ">Figure 12
<p>Fabricated prototype. (<b>a</b>) The top, (<b>b</b>) the bottom.</p> Full article ">Figure 13
<p>Experimental setup and schematic diagram.</p> Full article ">Figure 14
<p>Experimental normalized E-field distributions for the x-polarized waves from top to bottom: (<b>a</b>) magnitudes and (<b>b</b>) phases.</p> Full article ">Figure 15
<p>Experimental measurement of OAM E-field distributions for the y-polarized waves from bottom to top: (<b>a</b>) magnitudes and (<b>b</b>) phases.</p> Full article ">
Open AccessArticle
Modeling and Experimental Study of Vibration Energy Harvester with Triple-Frequency-Up Voltage Output by Vibration Mode Switching
by
Jiawen Xu, Zhikang Liu, Wenxing Dai, Ru Zhang and Jianjun Ge
Micromachines 2024, 15(8), 1013; https://doi.org/10.3390/mi15081013 - 6 Aug 2024
Abstract
Conventional wireless sensors rely on chemical batteries. Replacing or charging their batteries is tedious and costly in some situations. As usable kinetic energy exists in the environment, harvesting vibration energy and converting it into electrical energy has become a hotspot. However, the power
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Conventional wireless sensors rely on chemical batteries. Replacing or charging their batteries is tedious and costly in some situations. As usable kinetic energy exists in the environment, harvesting vibration energy and converting it into electrical energy has become a hotspot. However, the power output capability of a conventional piezoelectric energy harvester (PEH) is limited by its low operational frequency. This paper presents a new mechanism for achieving continuous triple-frequency-up voltage output in a PEH. The proposed system consists of a slender piezoelectric cantilever with two short cantilever-based stoppers. The piezoelectric cantilever undergoes a pure bending mode without contacting the stoppers. In addition, the beam switches into a new vibration mode by contacting the stoppers. The vibration modes switching yields reverses the signs of voltage outputs, inducing triple-frequency-up voltage output. Analytical and experimental investigations are presented, and it is shown that a significant triple-frequency up-conversion of the voltage output can be obtained over a wide frequency range. A peak power output of 3.03 mW was obtained. The proposed energy harvester can support a wireless sensor node.
Full article
(This article belongs to the Special Issue Self-Tuning and Self-Powered Energy Harvesting Technology toward Battery-Free IoT)
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![](https://pub.mdpi-res.com/micromachines/micromachines-15-01013/article_deploy/html/images/micromachines-15-01013-g001-550.jpg?1722956223)
Figure 1
Figure 1
<p>(<b>a</b>) Conventional frequency up-conversion mechanism by hitting (arrow: vibration direction); (<b>b</b>) proposed frequency up-conversion mechanism by mode switching (arrow: mode switching).</p> Full article ">Figure 2
<p>Operational principle of the frequency up-conversion.</p> Full article ">Figure 3
<p>Modeling of conventional 1st bending mode.</p> Full article ">Figure 4
<p>Modeling of stopper-forced vibration mode.</p> Full article ">Figure 5
<p>Vibration modes of the piezoelectric beam. (<b>a</b>) Without and (<b>b</b>) with hitting the stoppers.</p> Full article ">Figure 6
<p>Experimental set-up.</p> Full article ">Figure 7
<p>(<b>a</b>) Response and excitation and (<b>b</b>) RMS spectrum of the voltage output without triple-frequency up-conversion.</p> Full article ">Figure 8
<p>(<b>a</b>) Response and excitation and (<b>b</b>) RMS spectrum of the voltage output with triple-frequency up-conversion.</p> Full article ">Figure 9
<p>Photograph of bending mode switching (arrows mean the direction of the cycle of the motion).</p> Full article ">Figure 10
<p>RMS voltage frequency response. (<b>a</b>) Forward and (<b>b</b>) backward frequency response.</p> Full article ">Figure 11
<p>Diagrams of the frequency of excitation versus responses under excitations with amplitudes of (<b>a</b>) 0.037 g, (<b>b</b>) 0.745 g, (<b>c</b>) 2.235 g, and (<b>d</b>) 3.352 g.</p> Full article ">Figure 12
<p>The power output performance of the inner beam with different resistance loads. (<b>a</b>) Power outputs versus frequency with different loads and (<b>b</b>) peak power outputs with different loads (circles mean data point).</p> Full article ">Figure 13
<p>(<b>a</b>) Diagram and (<b>b</b>) experimental platform of the wireless sensing node.</p> Full article ">Figure 14
<p>Voltage on the capacitors.</p> Full article ">Figure 15
<p>Data received by the host computer.</p> Full article ">
<p>(<b>a</b>) Conventional frequency up-conversion mechanism by hitting (arrow: vibration direction); (<b>b</b>) proposed frequency up-conversion mechanism by mode switching (arrow: mode switching).</p> Full article ">Figure 2
<p>Operational principle of the frequency up-conversion.</p> Full article ">Figure 3
<p>Modeling of conventional 1st bending mode.</p> Full article ">Figure 4
<p>Modeling of stopper-forced vibration mode.</p> Full article ">Figure 5
<p>Vibration modes of the piezoelectric beam. (<b>a</b>) Without and (<b>b</b>) with hitting the stoppers.</p> Full article ">Figure 6
<p>Experimental set-up.</p> Full article ">Figure 7
<p>(<b>a</b>) Response and excitation and (<b>b</b>) RMS spectrum of the voltage output without triple-frequency up-conversion.</p> Full article ">Figure 8
<p>(<b>a</b>) Response and excitation and (<b>b</b>) RMS spectrum of the voltage output with triple-frequency up-conversion.</p> Full article ">Figure 9
<p>Photograph of bending mode switching (arrows mean the direction of the cycle of the motion).</p> Full article ">Figure 10
<p>RMS voltage frequency response. (<b>a</b>) Forward and (<b>b</b>) backward frequency response.</p> Full article ">Figure 11
<p>Diagrams of the frequency of excitation versus responses under excitations with amplitudes of (<b>a</b>) 0.037 g, (<b>b</b>) 0.745 g, (<b>c</b>) 2.235 g, and (<b>d</b>) 3.352 g.</p> Full article ">Figure 12
<p>The power output performance of the inner beam with different resistance loads. (<b>a</b>) Power outputs versus frequency with different loads and (<b>b</b>) peak power outputs with different loads (circles mean data point).</p> Full article ">Figure 13
<p>(<b>a</b>) Diagram and (<b>b</b>) experimental platform of the wireless sensing node.</p> Full article ">Figure 14
<p>Voltage on the capacitors.</p> Full article ">Figure 15
<p>Data received by the host computer.</p> Full article ">
Open AccessArticle
Application of a Modified First-Order Plate Theory to Structural Analysis of Sensitive Elements in a Pyroelectric Detector
by
Mengmeng Lian, Cuiying Fan, Xiaohan Zhan, Minghao Zhao, Guoshuai Qin and Chunsheng Lu
Micromachines 2024, 15(8), 1012; https://doi.org/10.3390/mi15081012 - 6 Aug 2024
Abstract
Pyroelectric materials, with piezoelectricity and pyroelectricity, have been widely used in infrared thermal detectors. In this paper, a modified first-order plate theory is extended to analyze a pyroelectric sensitive element structure. The displacement, temperature, and electric potential expand along the thickness direction. The
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Pyroelectric materials, with piezoelectricity and pyroelectricity, have been widely used in infrared thermal detectors. In this paper, a modified first-order plate theory is extended to analyze a pyroelectric sensitive element structure. The displacement, temperature, and electric potential expand along the thickness direction. The governing equation of the pyroelectric plate is built up. The potential distributions with upper and lower electrodes are obtained under different supported boundary conditions. The corresponding numerical results of electric potential are consistent with those obtained by the three-dimensional finite element method. Meanwhile, the theoretical results of electric potential are close to that of experiments. The influence of supported boundary conditions, piezoelectric effect, and plate thickness are analyzed. Numerical results show that the piezoelectric effect reduces the electric potential. The thickness of the pyroelectric plate enhances the electric potential but reduces the response speed of the detector. It is anticipated that the pyroelectric plate theory can provide a theoretical approach for the structural design of pyroelectric sensitive elements.
Full article
(This article belongs to the Special Issue Piezoelectric Devices and System in Micromachines)
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![](https://pub.mdpi-res.com/micromachines/micromachines-15-01012/article_deploy/html/images/micromachines-15-01012-g001-550.jpg?1722951324)
Figure 1
Figure 1
<p>Illustration of a plane coordinate system for the piezoelectric plate, in which two typical lines and points are respectively chosen as follows: Line 1: <span class="html-italic">x</span> <math display="inline"><semantics> <mo>∈</mo> </semantics></math> [0, <span class="html-italic">l<sub>a</sub></span>], <span class="html-italic">y</span> = <span class="html-italic">l<sub>b</sub></span>/2, <span class="html-italic">z</span> = <span class="html-italic">h</span>/2; Line 2: <span class="html-italic">x</span> <math display="inline"><semantics> <mo>∈</mo> </semantics></math> [0, <span class="html-italic">l<sub>a</sub></span>], <span class="html-italic">y</span> = <span class="html-italic">l<sub>b</sub></span>/2, <span class="html-italic">z</span> = 0; Point 1: (<span class="html-italic">x</span>,<span class="html-italic">y</span>,<span class="html-italic">z</span>) = (<span class="html-italic">l<sub>a</sub></span>/2, <span class="html-italic">l<sub>b</sub></span>/2, <span class="html-italic">h</span>/2); Point 2: (<span class="html-italic">x</span>,<span class="html-italic">y</span>,<span class="html-italic">z</span>) = (<span class="html-italic">l<sub>a</sub></span>/2, <span class="html-italic">l<sub>b</sub></span>/2, 0).</p> Full article ">Figure 2
<p>The distributions of (<b>a</b>) the temperature Δ<span class="html-italic">θ</span> and (<b>b</b>) the electric potential <span class="html-italic">φ</span> in a four-side clamped plate.</p> Full article ">Figure 3
<p>The distributions of (<b>a</b>) temperature and (<b>b</b>) electric potential along the plate thickness under a four-side clamped plate.</p> Full article ">Figure 4
<p>The distributions of electric potential along the <span class="html-italic">x</span>-axis when Δ<span class="html-italic">θ</span> = 2 × 10<sup>−4</sup> K for (<b>a</b>) four-side clamped; (<b>b</b>) four-side simply supported boundary conditions; (<b>c</b>) two-side clamped; and (<b>d</b>) four-point simply supported boundary conditions.</p> Full article ">Figure 5
<p>The influence of Δ<span class="html-italic">θ</span> on electric potential at Points 1 and 2 obtained from the present theory (line), and Ref. [<a href="#B28-micromachines-15-01012" class="html-bibr">28</a>] (hollow dot) under (<b>a</b>) four-side clamped and (<b>b</b>) four-point simply supported boundary conditions.</p> Full article ">Figure 6
<p>Illustration of the process of blackbody radiation in a pyroelectric detector.</p> Full article ">Figure 7
<p>Comparison between theorical and experimental potentials versus temperature on the upper surface in (<b>a</b>) PZT/PU composite material and (<b>b</b>) lithium tantalite.</p> Full article ">Figure 8
<p>Influence of the plate thickness <span class="html-italic">h</span> on electrical potential and change rate of temperature.</p> Full article ">
<p>Illustration of a plane coordinate system for the piezoelectric plate, in which two typical lines and points are respectively chosen as follows: Line 1: <span class="html-italic">x</span> <math display="inline"><semantics> <mo>∈</mo> </semantics></math> [0, <span class="html-italic">l<sub>a</sub></span>], <span class="html-italic">y</span> = <span class="html-italic">l<sub>b</sub></span>/2, <span class="html-italic">z</span> = <span class="html-italic">h</span>/2; Line 2: <span class="html-italic">x</span> <math display="inline"><semantics> <mo>∈</mo> </semantics></math> [0, <span class="html-italic">l<sub>a</sub></span>], <span class="html-italic">y</span> = <span class="html-italic">l<sub>b</sub></span>/2, <span class="html-italic">z</span> = 0; Point 1: (<span class="html-italic">x</span>,<span class="html-italic">y</span>,<span class="html-italic">z</span>) = (<span class="html-italic">l<sub>a</sub></span>/2, <span class="html-italic">l<sub>b</sub></span>/2, <span class="html-italic">h</span>/2); Point 2: (<span class="html-italic">x</span>,<span class="html-italic">y</span>,<span class="html-italic">z</span>) = (<span class="html-italic">l<sub>a</sub></span>/2, <span class="html-italic">l<sub>b</sub></span>/2, 0).</p> Full article ">Figure 2
<p>The distributions of (<b>a</b>) the temperature Δ<span class="html-italic">θ</span> and (<b>b</b>) the electric potential <span class="html-italic">φ</span> in a four-side clamped plate.</p> Full article ">Figure 3
<p>The distributions of (<b>a</b>) temperature and (<b>b</b>) electric potential along the plate thickness under a four-side clamped plate.</p> Full article ">Figure 4
<p>The distributions of electric potential along the <span class="html-italic">x</span>-axis when Δ<span class="html-italic">θ</span> = 2 × 10<sup>−4</sup> K for (<b>a</b>) four-side clamped; (<b>b</b>) four-side simply supported boundary conditions; (<b>c</b>) two-side clamped; and (<b>d</b>) four-point simply supported boundary conditions.</p> Full article ">Figure 5
<p>The influence of Δ<span class="html-italic">θ</span> on electric potential at Points 1 and 2 obtained from the present theory (line), and Ref. [<a href="#B28-micromachines-15-01012" class="html-bibr">28</a>] (hollow dot) under (<b>a</b>) four-side clamped and (<b>b</b>) four-point simply supported boundary conditions.</p> Full article ">Figure 6
<p>Illustration of the process of blackbody radiation in a pyroelectric detector.</p> Full article ">Figure 7
<p>Comparison between theorical and experimental potentials versus temperature on the upper surface in (<b>a</b>) PZT/PU composite material and (<b>b</b>) lithium tantalite.</p> Full article ">Figure 8
<p>Influence of the plate thickness <span class="html-italic">h</span> on electrical potential and change rate of temperature.</p> Full article ">
Open AccessReview
Micro-Opto-Electro-Mechanical Systems for High-Precision Displacement Sensing: A Review
by
Chenguang Xin, Yingkun Xu, Zhongyao Zhang and Mengwei Li
Micromachines 2024, 15(8), 1011; https://doi.org/10.3390/mi15081011 - 6 Aug 2024
Abstract
High-precision displacement sensing has been widely used across both scientific research and industrial applications. The recent interests in developing micro-opto-electro-mechanical systems (MOEMS) have given rise to an excellent platform for miniaturized displacement sensors. Advancement in this field during past years is now yielding
[...] Read more.
High-precision displacement sensing has been widely used across both scientific research and industrial applications. The recent interests in developing micro-opto-electro-mechanical systems (MOEMS) have given rise to an excellent platform for miniaturized displacement sensors. Advancement in this field during past years is now yielding integrated high-precision sensors which show great potential in applications ranging from photoacoustic spectroscopy to high-precision positioning and automation. In this review, we briefly summarize different techniques for high-precision displacement sensing based on MOEMS and discuss the challenges for future improvement.
Full article
(This article belongs to the Special Issue Realizing Optical Control through Mechatronics Systems)
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![](https://pub.mdpi-res.com/micromachines/micromachines-15-01011/article_deploy/html/images/micromachines-15-01011-g001-550.jpg?1722940451)
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Figure 1
<p>Classification of MOEMS displacement sensing techniques [<a href="#B25-micromachines-15-01011" class="html-bibr">25</a>,<a href="#B27-micromachines-15-01011" class="html-bibr">27</a>,<a href="#B28-micromachines-15-01011" class="html-bibr">28</a>,<a href="#B29-micromachines-15-01011" class="html-bibr">29</a>,<a href="#B30-micromachines-15-01011" class="html-bibr">30</a>,<a href="#B31-micromachines-15-01011" class="html-bibr">31</a>,<a href="#B32-micromachines-15-01011" class="html-bibr">32</a>,<a href="#B33-micromachines-15-01011" class="html-bibr">33</a>,<a href="#B34-micromachines-15-01011" class="html-bibr">34</a>,<a href="#B35-micromachines-15-01011" class="html-bibr">35</a>].</p> Full article ">Figure 2
<p>Displacement resolution with corresponding measuring range for MOEMS displacement sensing techniques based on different principles, including evanescent coupling, waveguiding Fabry-Perot (FP) resonance, geometrical overlapping and reflective FP resonance. (a-[<a href="#B41-micromachines-15-01011" class="html-bibr">41</a>], b-[<a href="#B27-micromachines-15-01011" class="html-bibr">27</a>], c-[<a href="#B43-micromachines-15-01011" class="html-bibr">43</a>], d-[<a href="#B44-micromachines-15-01011" class="html-bibr">44</a>], e-[<a href="#B42-micromachines-15-01011" class="html-bibr">42</a>], f-[<a href="#B28-micromachines-15-01011" class="html-bibr">28</a>], g-[<a href="#B23-micromachines-15-01011" class="html-bibr">23</a>], h-[<a href="#B24-micromachines-15-01011" class="html-bibr">24</a>], i-[<a href="#B45-micromachines-15-01011" class="html-bibr">45</a>], j-[<a href="#B46-micromachines-15-01011" class="html-bibr">46</a>], k-[<a href="#B47-micromachines-15-01011" class="html-bibr">47</a>], l-[<a href="#B48-micromachines-15-01011" class="html-bibr">48</a>], m-[<a href="#B29-micromachines-15-01011" class="html-bibr">29</a>], n-[<a href="#B49-micromachines-15-01011" class="html-bibr">49</a>]).</p> Full article ">Figure 3
<p>(<b>a</b>) Scanning electron microscope (SEM) image of a nanomechanical directional coupler consisting of two nano-waveguides [<a href="#B27-micromachines-15-01011" class="html-bibr">27</a>]. (<b>b</b>) Simulated transmission and electric field distribution before and after a displacement of 55 nm for the coupler shown in (<b>a</b>) [<a href="#B27-micromachines-15-01011" class="html-bibr">27</a>]. (<b>c</b>) Three-dimensional schematic illustration of a substrate-coupled free-standing waveguide [<a href="#B41-micromachines-15-01011" class="html-bibr">41</a>]. Inset is the SEM image correspondingly.</p> Full article ">Figure 4
<p>Displacement sensing based on a near-field coupled optical cavity [<a href="#B42-micromachines-15-01011" class="html-bibr">42</a>]. (<b>a</b>) Schematic diagram of an optical cavity coupled with a nano-waveguide. Inset is the SEM image of the cavity. The experimental relationship of the linewidth (red) and the negative optical frequency shift (blue) of the cavity on x<sub>0</sub>, which is the distance between the optical cavity to (<b>b</b>) a Si<sub>3</sub>N<sub>4</sub> string and (<b>c</b>) a sheet, respectively.</p> Full article ">Figure 5
<p>A fiber-tip MOEMS sensor based on evanescent coupling between two overlapping photonic crystal modes [<a href="#B44-micromachines-15-01011" class="html-bibr">44</a>]. (<b>a</b>) Design of the sensor. (<b>b</b>) SEM image of the sensor. (<b>c</b>) Setup used for the driven measurements.</p> Full article ">Figure 6
<p>(<b>a</b>) The SEM image of a MOEMS FP interferometer. Inside is the optical image of an assembled optical fiber [<a href="#B73-micromachines-15-01011" class="html-bibr">73</a>]. (<b>b</b>) Optical image of a MOEMS Mach–Zehnder interferometer [<a href="#B47-micromachines-15-01011" class="html-bibr">47</a>].</p> Full article ">Figure 7
<p>(<b>a</b>) Schematic diagram of a line-defect photonic crystal cavity [<a href="#B83-micromachines-15-01011" class="html-bibr">83</a>]. (<b>b</b>) Simulated relationship between the normalized intensity to the operating frequency with different input displacements in the line-defect cavity [<a href="#B83-micromachines-15-01011" class="html-bibr">83</a>]. (<b>c</b>) Schematic diagram of a MOEMS gyroscope based on photonic crystal resonant cavity formed by two distributed Bragg reflectors [<a href="#B32-micromachines-15-01011" class="html-bibr">32</a>]. (<b>d</b>) Simulated output spectra of the MOEMS gyroscope [<a href="#B32-micromachines-15-01011" class="html-bibr">32</a>].</p> Full article ">Figure 8
<p>A MOEMS accelerometer based on a finger-associated filter [<a href="#B92-micromachines-15-01011" class="html-bibr">92</a>]. (<b>a</b>) Schematic diagram of the accelerometer. (<b>b</b>) Simulated transmission with different displacements of the finger.</p> Full article ">Figure 9
<p>(<b>a</b>) Measuring principle of geometrical-overlapping based MOEMS displacement sensing [<a href="#B95-micromachines-15-01011" class="html-bibr">95</a>]. (<b>b</b>) Schematic setup of a MOEMS vibration sensor based on 2D rectangle arrays [<a href="#B29-micromachines-15-01011" class="html-bibr">29</a>]. (<b>c</b>) Schematic setup of a MOEMS accelerometer based on optical blocking of a proof mass [<a href="#B96-micromachines-15-01011" class="html-bibr">96</a>].</p> Full article ">Figure 10
<p>(<b>a</b>) Measuring principle of Talbot-effect-based MOEMS displacement sensing [<a href="#B103-micromachines-15-01011" class="html-bibr">103</a>]. (<b>b</b>) Simulated optical transmission of double-layer gratings with a relative displacement [<a href="#B33-micromachines-15-01011" class="html-bibr">33</a>]. (<b>c</b>) Schematic setup of a MOEMS accelerometer based on Talbot effect of optical gratings [<a href="#B103-micromachines-15-01011" class="html-bibr">103</a>].</p> Full article ">Figure 11
<p>(<b>a</b>) Principle of displacement sensing based on asymmetric FP resonance [<a href="#B115-micromachines-15-01011" class="html-bibr">115</a>]. (<b>b</b>) The relationships between the intensity of different diffracted orders to the gap thickness between two reflectors [<a href="#B45-micromachines-15-01011" class="html-bibr">45</a>]. (<b>c</b>) Schematic diagram of a MOEMS displacement sensor based on asymmetric FP resonance [<a href="#B45-micromachines-15-01011" class="html-bibr">45</a>].</p> Full article ">Figure 12
<p>Different optical gratings are used in the displacement sensing based on asymmetric FP resonance. (<b>a</b>) Traditional regular grating [<a href="#B34-micromachines-15-01011" class="html-bibr">34</a>]. (<b>b</b>) Quadrature phase-shift dual grating is used to generate quadrature outputs [<a href="#B21-micromachines-15-01011" class="html-bibr">21</a>]. (<b>c</b>) Four-region diffraction grating is used to eliminate the 0th-order diffracted beam [<a href="#B24-micromachines-15-01011" class="html-bibr">24</a>].</p> Full article ">Figure 13
<p>(<b>a</b>) Principle of displacement sensing based on diffractive interference [<a href="#B105-micromachines-15-01011" class="html-bibr">105</a>]. (<b>b</b>) Output signal as a function of in-plane displacement [<a href="#B116-micromachines-15-01011" class="html-bibr">116</a>]. (<b>c</b>) Schematic diagram of a miniaturized displacement sensor based on diffractive interference [<a href="#B105-micromachines-15-01011" class="html-bibr">105</a>].</p> Full article ">Figure 14
<p>(<b>a</b>) Schematic diagram of a reflective two-grating structure [<a href="#B119-micromachines-15-01011" class="html-bibr">119</a>]. (<b>b</b>) Relationship between the reflective intensity and in-plane displacement [<a href="#B119-micromachines-15-01011" class="html-bibr">119</a>]. (<b>c</b>) Schematic diagram of a MEOMS accelerometer based on Wood’s anomalies of diffractive gratings [<a href="#B120-micromachines-15-01011" class="html-bibr">120</a>].</p> Full article ">Figure 15
<p>(<b>a</b>) Principle of the triangulation measurement [<a href="#B122-micromachines-15-01011" class="html-bibr">122</a>]. (<b>b</b>) Received light power of photodiodes with a vertical displacement of the reflector [<a href="#B124-micromachines-15-01011" class="html-bibr">124</a>]. (<b>c</b>) Schematic diagrams of MOEMS displacement sensors based on triangulation measurement. Structures with and without a covering glass are shown in the left and the right images, respectively [<a href="#B124-micromachines-15-01011" class="html-bibr">124</a>,<a href="#B127-micromachines-15-01011" class="html-bibr">127</a>].</p> Full article ">Figure 16
<p>(<b>a</b>) Schematic diagram for a two-layer photonic crystal structure [<a href="#B82-micromachines-15-01011" class="html-bibr">82</a>]. (<b>b</b>) Transmission of a two-layer photonic crystal [<a href="#B84-micromachines-15-01011" class="html-bibr">84</a>]. The colors of the solid lines represent different spacings between the two layers. (<b>c</b>) SEM images of a fabricated MOMES displacement sensor based on photonic crystals [<a href="#B22-micromachines-15-01011" class="html-bibr">22</a>].</p> Full article ">
<p>Classification of MOEMS displacement sensing techniques [<a href="#B25-micromachines-15-01011" class="html-bibr">25</a>,<a href="#B27-micromachines-15-01011" class="html-bibr">27</a>,<a href="#B28-micromachines-15-01011" class="html-bibr">28</a>,<a href="#B29-micromachines-15-01011" class="html-bibr">29</a>,<a href="#B30-micromachines-15-01011" class="html-bibr">30</a>,<a href="#B31-micromachines-15-01011" class="html-bibr">31</a>,<a href="#B32-micromachines-15-01011" class="html-bibr">32</a>,<a href="#B33-micromachines-15-01011" class="html-bibr">33</a>,<a href="#B34-micromachines-15-01011" class="html-bibr">34</a>,<a href="#B35-micromachines-15-01011" class="html-bibr">35</a>].</p> Full article ">Figure 2
<p>Displacement resolution with corresponding measuring range for MOEMS displacement sensing techniques based on different principles, including evanescent coupling, waveguiding Fabry-Perot (FP) resonance, geometrical overlapping and reflective FP resonance. (a-[<a href="#B41-micromachines-15-01011" class="html-bibr">41</a>], b-[<a href="#B27-micromachines-15-01011" class="html-bibr">27</a>], c-[<a href="#B43-micromachines-15-01011" class="html-bibr">43</a>], d-[<a href="#B44-micromachines-15-01011" class="html-bibr">44</a>], e-[<a href="#B42-micromachines-15-01011" class="html-bibr">42</a>], f-[<a href="#B28-micromachines-15-01011" class="html-bibr">28</a>], g-[<a href="#B23-micromachines-15-01011" class="html-bibr">23</a>], h-[<a href="#B24-micromachines-15-01011" class="html-bibr">24</a>], i-[<a href="#B45-micromachines-15-01011" class="html-bibr">45</a>], j-[<a href="#B46-micromachines-15-01011" class="html-bibr">46</a>], k-[<a href="#B47-micromachines-15-01011" class="html-bibr">47</a>], l-[<a href="#B48-micromachines-15-01011" class="html-bibr">48</a>], m-[<a href="#B29-micromachines-15-01011" class="html-bibr">29</a>], n-[<a href="#B49-micromachines-15-01011" class="html-bibr">49</a>]).</p> Full article ">Figure 3
<p>(<b>a</b>) Scanning electron microscope (SEM) image of a nanomechanical directional coupler consisting of two nano-waveguides [<a href="#B27-micromachines-15-01011" class="html-bibr">27</a>]. (<b>b</b>) Simulated transmission and electric field distribution before and after a displacement of 55 nm for the coupler shown in (<b>a</b>) [<a href="#B27-micromachines-15-01011" class="html-bibr">27</a>]. (<b>c</b>) Three-dimensional schematic illustration of a substrate-coupled free-standing waveguide [<a href="#B41-micromachines-15-01011" class="html-bibr">41</a>]. Inset is the SEM image correspondingly.</p> Full article ">Figure 4
<p>Displacement sensing based on a near-field coupled optical cavity [<a href="#B42-micromachines-15-01011" class="html-bibr">42</a>]. (<b>a</b>) Schematic diagram of an optical cavity coupled with a nano-waveguide. Inset is the SEM image of the cavity. The experimental relationship of the linewidth (red) and the negative optical frequency shift (blue) of the cavity on x<sub>0</sub>, which is the distance between the optical cavity to (<b>b</b>) a Si<sub>3</sub>N<sub>4</sub> string and (<b>c</b>) a sheet, respectively.</p> Full article ">Figure 5
<p>A fiber-tip MOEMS sensor based on evanescent coupling between two overlapping photonic crystal modes [<a href="#B44-micromachines-15-01011" class="html-bibr">44</a>]. (<b>a</b>) Design of the sensor. (<b>b</b>) SEM image of the sensor. (<b>c</b>) Setup used for the driven measurements.</p> Full article ">Figure 6
<p>(<b>a</b>) The SEM image of a MOEMS FP interferometer. Inside is the optical image of an assembled optical fiber [<a href="#B73-micromachines-15-01011" class="html-bibr">73</a>]. (<b>b</b>) Optical image of a MOEMS Mach–Zehnder interferometer [<a href="#B47-micromachines-15-01011" class="html-bibr">47</a>].</p> Full article ">Figure 7
<p>(<b>a</b>) Schematic diagram of a line-defect photonic crystal cavity [<a href="#B83-micromachines-15-01011" class="html-bibr">83</a>]. (<b>b</b>) Simulated relationship between the normalized intensity to the operating frequency with different input displacements in the line-defect cavity [<a href="#B83-micromachines-15-01011" class="html-bibr">83</a>]. (<b>c</b>) Schematic diagram of a MOEMS gyroscope based on photonic crystal resonant cavity formed by two distributed Bragg reflectors [<a href="#B32-micromachines-15-01011" class="html-bibr">32</a>]. (<b>d</b>) Simulated output spectra of the MOEMS gyroscope [<a href="#B32-micromachines-15-01011" class="html-bibr">32</a>].</p> Full article ">Figure 8
<p>A MOEMS accelerometer based on a finger-associated filter [<a href="#B92-micromachines-15-01011" class="html-bibr">92</a>]. (<b>a</b>) Schematic diagram of the accelerometer. (<b>b</b>) Simulated transmission with different displacements of the finger.</p> Full article ">Figure 9
<p>(<b>a</b>) Measuring principle of geometrical-overlapping based MOEMS displacement sensing [<a href="#B95-micromachines-15-01011" class="html-bibr">95</a>]. (<b>b</b>) Schematic setup of a MOEMS vibration sensor based on 2D rectangle arrays [<a href="#B29-micromachines-15-01011" class="html-bibr">29</a>]. (<b>c</b>) Schematic setup of a MOEMS accelerometer based on optical blocking of a proof mass [<a href="#B96-micromachines-15-01011" class="html-bibr">96</a>].</p> Full article ">Figure 10
<p>(<b>a</b>) Measuring principle of Talbot-effect-based MOEMS displacement sensing [<a href="#B103-micromachines-15-01011" class="html-bibr">103</a>]. (<b>b</b>) Simulated optical transmission of double-layer gratings with a relative displacement [<a href="#B33-micromachines-15-01011" class="html-bibr">33</a>]. (<b>c</b>) Schematic setup of a MOEMS accelerometer based on Talbot effect of optical gratings [<a href="#B103-micromachines-15-01011" class="html-bibr">103</a>].</p> Full article ">Figure 11
<p>(<b>a</b>) Principle of displacement sensing based on asymmetric FP resonance [<a href="#B115-micromachines-15-01011" class="html-bibr">115</a>]. (<b>b</b>) The relationships between the intensity of different diffracted orders to the gap thickness between two reflectors [<a href="#B45-micromachines-15-01011" class="html-bibr">45</a>]. (<b>c</b>) Schematic diagram of a MOEMS displacement sensor based on asymmetric FP resonance [<a href="#B45-micromachines-15-01011" class="html-bibr">45</a>].</p> Full article ">Figure 12
<p>Different optical gratings are used in the displacement sensing based on asymmetric FP resonance. (<b>a</b>) Traditional regular grating [<a href="#B34-micromachines-15-01011" class="html-bibr">34</a>]. (<b>b</b>) Quadrature phase-shift dual grating is used to generate quadrature outputs [<a href="#B21-micromachines-15-01011" class="html-bibr">21</a>]. (<b>c</b>) Four-region diffraction grating is used to eliminate the 0th-order diffracted beam [<a href="#B24-micromachines-15-01011" class="html-bibr">24</a>].</p> Full article ">Figure 13
<p>(<b>a</b>) Principle of displacement sensing based on diffractive interference [<a href="#B105-micromachines-15-01011" class="html-bibr">105</a>]. (<b>b</b>) Output signal as a function of in-plane displacement [<a href="#B116-micromachines-15-01011" class="html-bibr">116</a>]. (<b>c</b>) Schematic diagram of a miniaturized displacement sensor based on diffractive interference [<a href="#B105-micromachines-15-01011" class="html-bibr">105</a>].</p> Full article ">Figure 14
<p>(<b>a</b>) Schematic diagram of a reflective two-grating structure [<a href="#B119-micromachines-15-01011" class="html-bibr">119</a>]. (<b>b</b>) Relationship between the reflective intensity and in-plane displacement [<a href="#B119-micromachines-15-01011" class="html-bibr">119</a>]. (<b>c</b>) Schematic diagram of a MEOMS accelerometer based on Wood’s anomalies of diffractive gratings [<a href="#B120-micromachines-15-01011" class="html-bibr">120</a>].</p> Full article ">Figure 15
<p>(<b>a</b>) Principle of the triangulation measurement [<a href="#B122-micromachines-15-01011" class="html-bibr">122</a>]. (<b>b</b>) Received light power of photodiodes with a vertical displacement of the reflector [<a href="#B124-micromachines-15-01011" class="html-bibr">124</a>]. (<b>c</b>) Schematic diagrams of MOEMS displacement sensors based on triangulation measurement. Structures with and without a covering glass are shown in the left and the right images, respectively [<a href="#B124-micromachines-15-01011" class="html-bibr">124</a>,<a href="#B127-micromachines-15-01011" class="html-bibr">127</a>].</p> Full article ">Figure 16
<p>(<b>a</b>) Schematic diagram for a two-layer photonic crystal structure [<a href="#B82-micromachines-15-01011" class="html-bibr">82</a>]. (<b>b</b>) Transmission of a two-layer photonic crystal [<a href="#B84-micromachines-15-01011" class="html-bibr">84</a>]. The colors of the solid lines represent different spacings between the two layers. (<b>c</b>) SEM images of a fabricated MOMES displacement sensor based on photonic crystals [<a href="#B22-micromachines-15-01011" class="html-bibr">22</a>].</p> Full article ">
Open AccessArticle
Replication of Radial Pulses Using Magneto-Rheological Fluids
by
Miranda Eaton, Jeong-Hoi Koo, Tae-Heon Yang and Young-Min Kim
Micromachines 2024, 15(8), 1010; https://doi.org/10.3390/mi15081010 - 6 Aug 2024
Abstract
The radial pulse is a critical health marker with expanding applications in wearable technology. To improve these applications, developing a pulse generator that consistently produces realistic pulses is crucial for validation and training. The goal of this study was to design and test
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The radial pulse is a critical health marker with expanding applications in wearable technology. To improve these applications, developing a pulse generator that consistently produces realistic pulses is crucial for validation and training. The goal of this study was to design and test a cost-effective pulse simulator that can accurately replicate a wide range of age-dependent radial pulses with simplicity and precision. To this end, this study incorporated a magneto-rheological (MR) fluid device into a cam-based pulse simulator. The MR device, as a key component, enables pulse shaping without the need for additional cams, substantially reducing the cost and complexity of control compared with existing pulse simulators. To evaluate the performance of the MR pulse simulator, the root-mean-square (RMS) error criterion (less than 5%) was used to compare the experimentally obtained pulse waveform with the in vivo pulse waveform for specific age groups. After demonstrating that the MR simulator could produce three representative in vivo pulses, a parametric study was conducted to show the feasibility of the slope-based pulse-shaping method for the MR pulse simulator to continuously generate a range of age-related pulses.
Full article
(This article belongs to the Special Issue Magnetorheological Materials and Application Systems)
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![](https://pub.mdpi-res.com/micromachines/micromachines-15-01010/article_deploy/html/images/micromachines-15-01010-g001-550.jpg?1722917678)
Figure 1
Figure 1
<p>Illustration of experimental set-up, including cam pulse generator, electromagnet, frictionless plunger assembly, and displacement sensor.</p> Full article ">Figure 2
<p>(<b>a</b>) Empty MR fluid chamber with exposed silicone tubing; (<b>b</b>) fully assembled chamber filled with MR fluid and covered with film and lid.</p> Full article ">Figure 3
<p>(<b>a</b>) Input duty values programmed in the micro-controller; (<b>b</b>) pulse width modulation (PWM) signal generated by the micro-controller; (<b>c</b>) resulting magnetic field from input PWM signal; and (<b>d</b>) age-dependent pulse generation measured by the laser displacement sensor.</p> Full article ">Figure 4
<p>(<b>a</b>) Example of range of age-related in vivo radial pulse waveforms; (<b>b</b>) normalized pulse waveforms for ages 10–80.</p> Full article ">Figure 5
<p>(<b>a</b>) MR pulse-shaping cam; (<b>b</b>) pulse waveforms generated by baseline cam for (<b>c</b>) 20, 50, and 80-year-old normalized waveforms into which the base pulse waveform is shaped.</p> Full article ">Figure 6
<p>(<b>a</b>) Target 20-year-old in vivo pulse to be shaped; (<b>b</b>) duty values and magnetic field used to shape the base pulse into a 20-year-old pulse; and (<b>c</b>) resulting displacement and experimental displacement compared with 20-year-old in vivo pulse.</p> Full article ">Figure 7
<p>(<b>a</b>) Target 50-year-old in vivo pulse to be shaped; (<b>b</b>) duty values and magnetic field used to shape the base pulse into a 50-year-old pulse; and (<b>c</b>) resulting displacement and experimental displacement compared with 50-year-old in vivo pulse.</p> Full article ">Figure 8
<p>(<b>a</b>) Target 80-year-old in vivo pulse to be shaped; (<b>b</b>) duty values and magnetic field used to shape the base pulse into an 80-year-old pulse; and (<b>c</b>) resulting displacement and experimental displacement compared with 80-year-old in vivo pulse.</p> Full article ">Figure 9
<p>(<b>a</b>) Example of 5 slope zones analyzed in 80-year-old in vivo pulse; (<b>b</b>) 5 slopes that represent the 80-year-old in vivo pulse.</p> Full article ">Figure 10
<p>(<b>a</b>) Schematic design of half-cam, which maintains a constant radius for half of the disk; (<b>b</b>) normalized displacement graph of half-cam, illustrating constant displacement due to a constant radius.; (<b>c</b>) Fabricated actual half-cam using wire-cutting, (<b>d</b>) actual normalized displacement by half-cam.</p> Full article ">Figure 11
<p>Graph showing three different variables tested during parametric study: duty slope, time duration, and magnitude.</p> Full article ">Figure 12
<p>Results showing effect of changing duty slope on displacement slope. (<b>a</b>) Changing duty slope from 0.03%/s to 0.75%/s. (<b>b</b>) Resulting normalized displacement slope from changing duty slopes; displacement slopes are taken from within the boxed area.</p> Full article ">Figure 13
<p>Results showing effect of changing duty magnitude on displacement slope. (<b>a</b>) Changing initial duty value from 20 to 70%. (<b>b</b>) Normalized displacement from changing duty magnitude; displacement slopes are taken from within the boxed area.</p> Full article ">Figure 14
<p>Results showing effect of changing time duration on displacement slope. (<b>a</b>) Changing total time duration from 0.100 to 0.275 s. (<b>b</b>) Normalized displacement from changing duty magnitude; displacement slopes are taken from within the boxed area.</p> Full article ">
<p>Illustration of experimental set-up, including cam pulse generator, electromagnet, frictionless plunger assembly, and displacement sensor.</p> Full article ">Figure 2
<p>(<b>a</b>) Empty MR fluid chamber with exposed silicone tubing; (<b>b</b>) fully assembled chamber filled with MR fluid and covered with film and lid.</p> Full article ">Figure 3
<p>(<b>a</b>) Input duty values programmed in the micro-controller; (<b>b</b>) pulse width modulation (PWM) signal generated by the micro-controller; (<b>c</b>) resulting magnetic field from input PWM signal; and (<b>d</b>) age-dependent pulse generation measured by the laser displacement sensor.</p> Full article ">Figure 4
<p>(<b>a</b>) Example of range of age-related in vivo radial pulse waveforms; (<b>b</b>) normalized pulse waveforms for ages 10–80.</p> Full article ">Figure 5
<p>(<b>a</b>) MR pulse-shaping cam; (<b>b</b>) pulse waveforms generated by baseline cam for (<b>c</b>) 20, 50, and 80-year-old normalized waveforms into which the base pulse waveform is shaped.</p> Full article ">Figure 6
<p>(<b>a</b>) Target 20-year-old in vivo pulse to be shaped; (<b>b</b>) duty values and magnetic field used to shape the base pulse into a 20-year-old pulse; and (<b>c</b>) resulting displacement and experimental displacement compared with 20-year-old in vivo pulse.</p> Full article ">Figure 7
<p>(<b>a</b>) Target 50-year-old in vivo pulse to be shaped; (<b>b</b>) duty values and magnetic field used to shape the base pulse into a 50-year-old pulse; and (<b>c</b>) resulting displacement and experimental displacement compared with 50-year-old in vivo pulse.</p> Full article ">Figure 8
<p>(<b>a</b>) Target 80-year-old in vivo pulse to be shaped; (<b>b</b>) duty values and magnetic field used to shape the base pulse into an 80-year-old pulse; and (<b>c</b>) resulting displacement and experimental displacement compared with 80-year-old in vivo pulse.</p> Full article ">Figure 9
<p>(<b>a</b>) Example of 5 slope zones analyzed in 80-year-old in vivo pulse; (<b>b</b>) 5 slopes that represent the 80-year-old in vivo pulse.</p> Full article ">Figure 10
<p>(<b>a</b>) Schematic design of half-cam, which maintains a constant radius for half of the disk; (<b>b</b>) normalized displacement graph of half-cam, illustrating constant displacement due to a constant radius.; (<b>c</b>) Fabricated actual half-cam using wire-cutting, (<b>d</b>) actual normalized displacement by half-cam.</p> Full article ">Figure 11
<p>Graph showing three different variables tested during parametric study: duty slope, time duration, and magnitude.</p> Full article ">Figure 12
<p>Results showing effect of changing duty slope on displacement slope. (<b>a</b>) Changing duty slope from 0.03%/s to 0.75%/s. (<b>b</b>) Resulting normalized displacement slope from changing duty slopes; displacement slopes are taken from within the boxed area.</p> Full article ">Figure 13
<p>Results showing effect of changing duty magnitude on displacement slope. (<b>a</b>) Changing initial duty value from 20 to 70%. (<b>b</b>) Normalized displacement from changing duty magnitude; displacement slopes are taken from within the boxed area.</p> Full article ">Figure 14
<p>Results showing effect of changing time duration on displacement slope. (<b>a</b>) Changing total time duration from 0.100 to 0.275 s. (<b>b</b>) Normalized displacement from changing duty magnitude; displacement slopes are taken from within the boxed area.</p> Full article ">
Open AccessArticle
Two CMOS Wilkinson Power Dividers Using High Slow-Wave and Low-Loss Transmission Lines
by
Chatrpol Pakasiri, Wei-Sen Teng and Sen Wang
Micromachines 2024, 15(8), 1009; https://doi.org/10.3390/mi15081009 - 5 Aug 2024
Abstract
This work presents two Wilkinson power dividers (WPDs) using multi-layer pseudo coplanar waveguide (PCPW) structures. The PCPW-based WPDs were designed, implemented, and verified in a standard 180 nm CMOS process. The proposed PCPW features high slow-wave and low-loss performances compared to other common
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This work presents two Wilkinson power dividers (WPDs) using multi-layer pseudo coplanar waveguide (PCPW) structures. The PCPW-based WPDs were designed, implemented, and verified in a standard 180 nm CMOS process. The proposed PCPW features high slow-wave and low-loss performances compared to other common transmission lines. The two WPDs are based on the same PCPW structure parameters in terms of line width, spacing, and used metal layers. One WPD was realized in a straight PCPW-based layout, and the other WPD was realized in a meandered PCPW-based layout. Both the two WPDs worked up to V-band frequencies, as expected, which also demonstrates that the PCPW guiding structure is less susceptible to the effects of meanderings on the propagation constant and characteristic impedance. The meandered design shows that the measured insertion losses were about 5.1 dB, and its return losses were better than 17.5 dB at 60 GHz. In addition, its isolation, amplitude imbalance, and phase imbalance were 18.5 dB, 0.03 dB, and 0.4°, respectively. The core area was merely 0.2 mm × 0.23 mm, or 1.8 × 10−3λo2.
Full article
(This article belongs to the Special Issue Microwave Passive Components, 2nd Edition)
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![](https://pub.mdpi-res.com/micromachines/micromachines-15-01009/article_deploy/html/images/micromachines-15-01009-g001-550.jpg?1722844638)
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<p>A Conventional WPD topology using two 70.7-Ω quarter-wavelength transmission lines and one 100-Ω isolation resistor.</p> Full article ">Figure 2
<p>Cross-section of a standard 0.18 μm CMOS process.</p> Full article ">Figure 3
<p>Cross-section view of (<b>a</b>) the thin-film microstrip line, (<b>b</b>) coplanar waveguide, and (<b>c</b>) conductor-back coplanar waveguide.</p> Full article ">Figure 4
<p>(<b>a</b>) Cross-sectional view and (<b>b</b>) 3D structure of the PCPW.</p> Full article ">Figure 5
<p>(<b>a</b>) Simulated <span class="html-italic">Z<sub>c</sub></span> of the PCPW structure. Simulated (<b>b</b>) slow-wave factor (SWF) and (<b>c</b>) attenuation results of 70.7-Ω CBCPW, CPW, TFMSL, and PCPW structures.</p> Full article ">Figure 6
<p>Chip photo of the two proposed WPDs. (<b>a</b>) Straight PCPW-based layout and (<b>b</b>) meandered PCPW-based layout.</p> Full article ">Figure 7
<p>Simulated and measured results: (<b>a</b>) insertion and return losses, (<b>b</b>) isolation, and (<b>c</b>) phase and amplitude imbalances of the straight PCPW-based WPD.</p> Full article ">Figure 7 Cont.
<p>Simulated and measured results: (<b>a</b>) insertion and return losses, (<b>b</b>) isolation, and (<b>c</b>) phase and amplitude imbalances of the straight PCPW-based WPD.</p> Full article ">Figure 8
<p>Simulated and measured results: (<b>a</b>) insertion and return losses, (<b>b</b>) isolation, and (<b>c</b>) phase and amplitude imbalances of the meandered PCPW-based WPD.</p> Full article ">Figure 8 Cont.
<p>Simulated and measured results: (<b>a</b>) insertion and return losses, (<b>b</b>) isolation, and (<b>c</b>) phase and amplitude imbalances of the meandered PCPW-based WPD.</p> Full article ">
<p>A Conventional WPD topology using two 70.7-Ω quarter-wavelength transmission lines and one 100-Ω isolation resistor.</p> Full article ">Figure 2
<p>Cross-section of a standard 0.18 μm CMOS process.</p> Full article ">Figure 3
<p>Cross-section view of (<b>a</b>) the thin-film microstrip line, (<b>b</b>) coplanar waveguide, and (<b>c</b>) conductor-back coplanar waveguide.</p> Full article ">Figure 4
<p>(<b>a</b>) Cross-sectional view and (<b>b</b>) 3D structure of the PCPW.</p> Full article ">Figure 5
<p>(<b>a</b>) Simulated <span class="html-italic">Z<sub>c</sub></span> of the PCPW structure. Simulated (<b>b</b>) slow-wave factor (SWF) and (<b>c</b>) attenuation results of 70.7-Ω CBCPW, CPW, TFMSL, and PCPW structures.</p> Full article ">Figure 6
<p>Chip photo of the two proposed WPDs. (<b>a</b>) Straight PCPW-based layout and (<b>b</b>) meandered PCPW-based layout.</p> Full article ">Figure 7
<p>Simulated and measured results: (<b>a</b>) insertion and return losses, (<b>b</b>) isolation, and (<b>c</b>) phase and amplitude imbalances of the straight PCPW-based WPD.</p> Full article ">Figure 7 Cont.
<p>Simulated and measured results: (<b>a</b>) insertion and return losses, (<b>b</b>) isolation, and (<b>c</b>) phase and amplitude imbalances of the straight PCPW-based WPD.</p> Full article ">Figure 8
<p>Simulated and measured results: (<b>a</b>) insertion and return losses, (<b>b</b>) isolation, and (<b>c</b>) phase and amplitude imbalances of the meandered PCPW-based WPD.</p> Full article ">Figure 8 Cont.
<p>Simulated and measured results: (<b>a</b>) insertion and return losses, (<b>b</b>) isolation, and (<b>c</b>) phase and amplitude imbalances of the meandered PCPW-based WPD.</p> Full article ">
Open AccessArticle
Temperature Characteristics Modeling for GaN PA Based on PSO-ELM
by
Qian Lin and Meiqian Wang
Micromachines 2024, 15(8), 1008; https://doi.org/10.3390/mi15081008 - 5 Aug 2024
Abstract
In order to solve the performance prediction and design optimization of power amplifiers (PAs), the performance parameters of Gallium Nitride high-electron-mobility transistor (GaN HEMT) PAs at different temperatures are modeled based on the particle swarm optimization–extreme learning machine (PSO-ELM) and extreme learning machine
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In order to solve the performance prediction and design optimization of power amplifiers (PAs), the performance parameters of Gallium Nitride high-electron-mobility transistor (GaN HEMT) PAs at different temperatures are modeled based on the particle swarm optimization–extreme learning machine (PSO-ELM) and extreme learning machine (ELM) in this paper. Then, it can be seen that the prediction accuracy of the PSO-ELM model is superior to that of ELM with a minimum mean square error (MSE) of 0.0006, which indicates the PSO-ELM model has a stronger generalization ability when dealing with the nonlinear relationship between temperature and PA performance. Therefore, this investigation can provide vital theoretical support for the performance optimization of PA design.
Full article
(This article belongs to the Topic New Developments for Circuit Design: Synthesis, Modeling, Simulation, and Applications)
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![](https://pub.mdpi-res.com/micromachines/micromachines-15-01008/article_deploy/html/images/micromachines-15-01008-g001-550.jpg?1722848672)
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<p>Physical photograph of the GaN PA.</p> Full article ">Figure 2
<p>Basic structure of ELM for GaN PA.</p> Full article ">Figure 3
<p>Modeling flowchart of ELM model for GaN PA.</p> Full article ">Figure 4
<p>Modeling flowchart of PSO-ELM for GaN PA performance.</p> Full article ">Figure 5
<p>Prediction model based on ELM for GaN PA performance.</p> Full article ">Figure 6
<p>Prediction results of S-parameters based on ELM for GaN PA. (<b>a</b>) S<sub>11</sub>. (<b>b</b>) S<sub>21</sub>. (<b>c</b>) S<sub>22</sub>.</p> Full article ">Figure 6 Cont.
<p>Prediction results of S-parameters based on ELM for GaN PA. (<b>a</b>) S<sub>11</sub>. (<b>b</b>) S<sub>21</sub>. (<b>c</b>) S<sub>22</sub>.</p> Full article ">Figure 7
<p>Prediction results of Pout based on ELM for GaN PA.</p> Full article ">Figure 8
<p>Prediction results of Gain based on ELM for GaN PA.</p> Full article ">Figure 9
<p>Prediction results of S-parameters based on PSO-ELM for GaN PA. (<b>a</b>) S<sub>11</sub>. (<b>b</b>) S<sub>21</sub>. (<b>c</b>) S<sub>22</sub>.</p> Full article ">Figure 9 Cont.
<p>Prediction results of S-parameters based on PSO-ELM for GaN PA. (<b>a</b>) S<sub>11</sub>. (<b>b</b>) S<sub>21</sub>. (<b>c</b>) S<sub>22</sub>.</p> Full article ">Figure 10
<p>Prediction results of Pout based on PSO-ELM for GaN PA.</p> Full article ">Figure 11
<p>Prediction results of Gain based on PSO-ELM for GaN PA.</p> Full article ">
<p>Physical photograph of the GaN PA.</p> Full article ">Figure 2
<p>Basic structure of ELM for GaN PA.</p> Full article ">Figure 3
<p>Modeling flowchart of ELM model for GaN PA.</p> Full article ">Figure 4
<p>Modeling flowchart of PSO-ELM for GaN PA performance.</p> Full article ">Figure 5
<p>Prediction model based on ELM for GaN PA performance.</p> Full article ">Figure 6
<p>Prediction results of S-parameters based on ELM for GaN PA. (<b>a</b>) S<sub>11</sub>. (<b>b</b>) S<sub>21</sub>. (<b>c</b>) S<sub>22</sub>.</p> Full article ">Figure 6 Cont.
<p>Prediction results of S-parameters based on ELM for GaN PA. (<b>a</b>) S<sub>11</sub>. (<b>b</b>) S<sub>21</sub>. (<b>c</b>) S<sub>22</sub>.</p> Full article ">Figure 7
<p>Prediction results of Pout based on ELM for GaN PA.</p> Full article ">Figure 8
<p>Prediction results of Gain based on ELM for GaN PA.</p> Full article ">Figure 9
<p>Prediction results of S-parameters based on PSO-ELM for GaN PA. (<b>a</b>) S<sub>11</sub>. (<b>b</b>) S<sub>21</sub>. (<b>c</b>) S<sub>22</sub>.</p> Full article ">Figure 9 Cont.
<p>Prediction results of S-parameters based on PSO-ELM for GaN PA. (<b>a</b>) S<sub>11</sub>. (<b>b</b>) S<sub>21</sub>. (<b>c</b>) S<sub>22</sub>.</p> Full article ">Figure 10
<p>Prediction results of Pout based on PSO-ELM for GaN PA.</p> Full article ">Figure 11
<p>Prediction results of Gain based on PSO-ELM for GaN PA.</p> Full article ">
Open AccessReview
Recent Advances in Photoacoustic Imaging: Current Status and Future Perspectives
by
Huibin Liu, Xiangyu Teng, Shuxuan Yu, Wenguang Yang, Tiantian Kong and Tangying Liu
Micromachines 2024, 15(8), 1007; https://doi.org/10.3390/mi15081007 - 4 Aug 2024
Abstract
Photoacoustic imaging (PAI) is an emerging hybrid imaging modality that combines high-contrast optical imaging with high-spatial-resolution ultrasound imaging. PAI can provide a high spatial resolution and significant imaging depth by utilizing the distinctive spectroscopic characteristics of tissue, which gives it a wide variety
[...] Read more.
Photoacoustic imaging (PAI) is an emerging hybrid imaging modality that combines high-contrast optical imaging with high-spatial-resolution ultrasound imaging. PAI can provide a high spatial resolution and significant imaging depth by utilizing the distinctive spectroscopic characteristics of tissue, which gives it a wide variety of applications in biomedicine and preclinical research. In addition, it is non-ionizing and non-invasive, and photoacoustic (PA) signals are generated by a short-pulse laser under thermal expansion. In this study, we describe the basic principles of PAI, recent advances in research in human and animal tissues, and future perspectives.
Full article
(This article belongs to the Special Issue Photoacoustic-Based Sensing Systems: Advances, Applications, and Innovative Measurement Strategies)
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![](https://pub.mdpi-res.com/micromachines/micromachines-15-01007/article_deploy/html/images/micromachines-15-01007-g001-550.jpg?1722764054)
Figure 1
Figure 1
<p>(<b>A</b>) Diagram of photoacoustic effect (reproduced from Ref. [<a href="#B10-micromachines-15-01007" class="html-bibr">10</a>]). (<b>B</b>) Schematic diagram of PAI system. LDU: laser driver unit; CSP: circular scanning plate; S: sample; MPS: motor pulley system; M: motor; DAQ: data-acquisition card; R/A/F: ultrasound signal receiver, amplifier, and filter; UST: ultrasound transducer (reproduced from Ref. [<a href="#B11-micromachines-15-01007" class="html-bibr">11</a>]). (<b>C</b>) The dependence of energy intensity per pulse and induced acoustic pressure. Acoustic pressure increases linearly with input energy intensity (reproduced from Ref. [<a href="#B12-micromachines-15-01007" class="html-bibr">12</a>]).</p> Full article ">Figure 2
<p>Photoacoustic signals generated for PA amplitude image excited with a 460 nm LED (<b>a</b>), 530 nm LED (<b>b</b>), 590 nm LED (<b>c</b>), and 620 nm LED (<b>d</b>) (reproduced from Ref. [<a href="#B17-micromachines-15-01007" class="html-bibr">17</a>]).</p> Full article ">Figure 3
<p>The spectral sensitivity of PZT (<b>A</b>) and cMUT (<b>B</b>) as a function of the angle (reproduced from Ref. [<a href="#B31-micromachines-15-01007" class="html-bibr">31</a>]). (<b>C</b>) US and PA images of rat rectum with PMN-PT/epoxy 1-3 composite, PMN-PT, and PZT composite (reproduced from Ref. [<a href="#B33-micromachines-15-01007" class="html-bibr">33</a>]). (<b>D</b>) (<b>a</b>) The reconstructed PA image with 64-, 128-, and 256-element transducer. (<b>b</b>) PA amplitude diagram of vessel along the radial direction. (<b>c</b>) PA amplitude diagram of vessel along the transversal direction (reproduced from Ref. [<a href="#B41-micromachines-15-01007" class="html-bibr">41</a>]).</p> Full article ">Figure 4
<p>(<b>A</b>) Optical absorption coefficient of principal tissue chromophores (reproduced from Ref. [<a href="#B91-micromachines-15-01007" class="html-bibr">91</a>]). (<b>B</b>) The schematic illustration of the CPQ nano-probe activated by MMPs. The conjugated Black Hole Quencher 3 (BHQ3)–peptide–CuS could be cleaved after exposure to MMPs so that the BHQ3 could be released from nanoparticles (reproduced from Ref. [<a href="#B79-micromachines-15-01007" class="html-bibr">79</a>]). (<b>C</b>) Schematic diagram of synthesized silver nanoplates with rounded and more stable tips (reproduced from Ref. [<a href="#B82-micromachines-15-01007" class="html-bibr">82</a>]). (<b>D</b>) Schematic illustration of the preparation of cRGD-PDI NPs and specifical mechanism for lighting early thrombus (reproduced from Ref. [<a href="#B83-micromachines-15-01007" class="html-bibr">83</a>]). (<b>E</b>) Schematic depiction of biodegradable gold nanoparticles. The contrast agent is generated by small AuNPs incorporated into a biodegradable PCPP to achieve diagnostic potential as well as be degraded in vivo into harmless byproducts for excretion after some period (reproduced from Ref. [<a href="#B84-micromachines-15-01007" class="html-bibr">84</a>]).</p> Full article ">Figure 5
<p>(<b>A</b>) PA images and photographs of skin with pigmentation and depigmentation in epidermal structures (reproduced from Ref. [<a href="#B106-micromachines-15-01007" class="html-bibr">106</a>]). (<b>B</b>) PA images and photographs of PWS skin and normal skin (reproduced from Ref. [<a href="#B106-micromachines-15-01007" class="html-bibr">106</a>]). (<b>C</b>) In vivo PA/US images of the human forearm obtained with 40, 21, and 15 MHz frequency transducer probes at 1064 nm wavelength. (<b>a</b>) Photograph of forearm skin from the subject. Fused PA/US imaging acquired with 40 (<b>b</b>), 21 (<b>c</b>), and 15 (<b>d</b>) MHz frequency transducer probes, as well as corresponding (Maximum Intensity Projection) MIP images through the PA volumes of the human forearm (reproduced from Ref. [<a href="#B107-micromachines-15-01007" class="html-bibr">107</a>]). (<b>D</b>) Schematic illustration and PAM image of chicken breast piece with crossing hairs inserted ~1 mm below the surface. The resolution of hairs is ~15 dB SNR (reproduced from Ref. [<a href="#B108-micromachines-15-01007" class="html-bibr">108</a>]). (<b>E</b>) Photoacoustic/ultrasound images of a human proximal interphalangeal joint in sagittal and transverse planes. On the right side, the anatomical structures are indicated by ultrasound imaging (reproduced from Ref. [<a href="#B112-micromachines-15-01007" class="html-bibr">112</a>]).</p> Full article ">Figure 6
<p>(<b>A</b>) Cross-sectional images of IVPA and IVUS and merged images of IVPA-US (reproduced from Ref. [<a href="#B116-micromachines-15-01007" class="html-bibr">116</a>]). (<b>B</b>) Histopathology stained with special dye and magnified images of lipid deposition site (reproduced from Ref. [<a href="#B116-micromachines-15-01007" class="html-bibr">116</a>]). (<b>C</b>) PA images of a normal vessel by utilizing single-element (<b>a</b>) and dual-element (<b>b</b>) transducer as well as distribution of PA amplitude along the dashed line in (<b>a</b>,<b>b</b>). PA images of a normal vessel (<b>c</b>) and an atherosclerotic plaque (<b>d</b>) as well as corresponding bright-field optical images of a normal vessel and an atherosclerotic plaque. (<b>e</b>–<b>h</b>) Lipid-rich plaques in the atherosclerotic vessel sample stained with oil red (reproduced from Ref. [<a href="#B117-micromachines-15-01007" class="html-bibr">117</a>]).</p> Full article ">Figure 7
<p>(<b>A</b>) (<b>a</b>,<b>b</b>) Histological results for the normal cervical tissue and tissue lesion, (<b>c</b>) tissue image corresponding to the DMAP images, and (<b>d</b>) Depth Maximum Amplitude Projection (DMAP) image (reproduced from Ref. [<a href="#B118-micromachines-15-01007" class="html-bibr">118</a>]). (<b>B</b>) (<b>a</b>)A clear anatomical view is produced by combining photoacoustic-based cell-specific targeting with ultrasound imaging, (<b>b</b>) Imaging setup including the ultrasound probe and fiber illumination inserted through the urethra (reproduced from Ref. [<a href="#B67-micromachines-15-01007" class="html-bibr">67</a>]). (<b>C</b>) (<b>a</b>) anatomy of thyroid gland including cardiovascular and respiratory system. (<b>b</b>) PA image of the left thyroid lobe of volunteer. The vascular features of skin [<a href="#B71-micromachines-15-01007" class="html-bibr">71</a>,<a href="#B124-micromachines-15-01007" class="html-bibr">124</a>], muscles, and within the thyroid lobe [<a href="#B125-micromachines-15-01007" class="html-bibr">125</a>] are shown through leveling and normalizing from 0 to 1. (<b>c</b>) Ultrasound cross-sections of the left thyroid lobe. The superimposed areas in color represent directional power Doppler signals. C: carotid; T: thyroid; Tr: trachea; s: sternocleidomastoid muscle; m: infrahyoid muscle (reproduced from Ref. [<a href="#B122-micromachines-15-01007" class="html-bibr">122</a>]).</p> Full article ">Figure 8
<p>(<b>A</b>) PAM image of the vascular on a porcine ovary and corresponding photograph of the porcine ovary. The normalized PA amplitude is indicated by color bar (reproduced from Ref. [<a href="#B108-micromachines-15-01007" class="html-bibr">108</a>]). (<b>B</b>) PA image and fused 3D volume overlay (<b>c</b>) of vasculature system from freshly excised liver tissue using low-frequency (10–30 MHz) (<b>a</b>) and high-frequency (30–90 MHz) (<b>b</b>) detection (reproduced from Ref. [<a href="#B10-micromachines-15-01007" class="html-bibr">10</a>]). (<b>C</b>) Imaging of pig esophagus ex vivo. (<b>a</b>) Volumetric PA image of esophagus sample. (<b>b</b>) PA image of the region of cross-sectional esophagus wall in the dotted box corresponding to figure (<b>a</b>). (<b>c</b>) Histological image with the different layers of esophagus wall. EP: epithelium; M, mucosa; LP, lamina propria; MM, muscularis mucosa; MP, muscularis propria; SM, submucosa. (<b>d</b>) PA image of the different layers in the dotted box corresponding to figure (<b>b</b>). (<b>e</b>) Vasculature of the different esophageal layers revealed by anti-CD31 immunostaining. (<b>f</b>)The stained histological image of the different esophageal layers and corresponding to PA image of different layers. (reproduced from Ref. [<a href="#B129-micromachines-15-01007" class="html-bibr">129</a>]). (<b>D</b>) The microvascular distribution of lower lip during the healing of an ulcer wound. Row 1 in (<b>a</b>–<b>f</b>) presents ORPAM MAP images of ulcer wound. ORPAM B-scans of lip along the dashed white lines in row 1 are shown in row 2 (<b>a</b>–<b>f</b>). OCT B-scans are shown in row 3 (<b>a</b>–<b>f</b>) (reproduced from Ref. [<a href="#B131-micromachines-15-01007" class="html-bibr">131</a>]).</p> Full article ">Figure 9
<p>Brain blood oxygenation stimulated by carbon dioxide. (<b>A</b>–<b>C</b>) Deoxy-hemoglobin pseudocolor images from a single animal at different time points. (<b>D</b>–<b>F</b>) The darker blue represents an increase in deoxidation. The corresponding oxy-hemoglobin is in red. (<b>G</b>) shows a combination of oxy- and deoxy-hemoglobin signals corresponding to B and E. (<b>H</b>,<b>I</b>) The change in oxy- and deoxy-hemoglobin signals with time (reproduced from Ref. [<a href="#B133-micromachines-15-01007" class="html-bibr">133</a>]).</p> Full article ">Figure 10
<p>(<b>A</b>) Photoacoustic B-scan image of the beating heart in an athymic nude mouse. The preliminary image of cardiac structures is depicted, including blood vessels and the skin surface (reproduced from Ref. [<a href="#B135-micromachines-15-01007" class="html-bibr">135</a>]). (<b>B</b>) Photograph of the mouse ear showing blood vessels (<b>a</b>) and corresponding PA images (<b>b</b>,<b>c</b>). (<b>c</b>) is an enlarged region of the white line box in (<b>b</b>). Red blood cells are presented by the white arrows (reproduced from Ref. [<a href="#B136-micromachines-15-01007" class="html-bibr">136</a>]). (<b>C</b>) (<b>a</b>) MAP photoacoustic image of subcutaneous blood vessels in the upper dorsal region of rat. (<b>b</b>) The photograph from the dermal side of excised skin with transmission illumination corresponding to (<b>a</b>). A–E is the area enclosed by major blood vessels (reproduced from Ref. [<a href="#B138-micromachines-15-01007" class="html-bibr">138</a>]). (<b>D</b>) In vivo 3D photoacoustic images of the upper dorsal region of rat (reproduced from Ref. [<a href="#B138-micromachines-15-01007" class="html-bibr">138</a>]). (<b>E</b>) (<b>a</b>) The intravital whole-body imaging of mice after inoculating the tumor for a period of time. (<b>b</b>) The diagram of photoacoustic signals, which is obtained by scanning along two black dashed lines (reproduced from Ref. [<a href="#B139-micromachines-15-01007" class="html-bibr">139</a>]).</p> Full article ">
<p>(<b>A</b>) Diagram of photoacoustic effect (reproduced from Ref. [<a href="#B10-micromachines-15-01007" class="html-bibr">10</a>]). (<b>B</b>) Schematic diagram of PAI system. LDU: laser driver unit; CSP: circular scanning plate; S: sample; MPS: motor pulley system; M: motor; DAQ: data-acquisition card; R/A/F: ultrasound signal receiver, amplifier, and filter; UST: ultrasound transducer (reproduced from Ref. [<a href="#B11-micromachines-15-01007" class="html-bibr">11</a>]). (<b>C</b>) The dependence of energy intensity per pulse and induced acoustic pressure. Acoustic pressure increases linearly with input energy intensity (reproduced from Ref. [<a href="#B12-micromachines-15-01007" class="html-bibr">12</a>]).</p> Full article ">Figure 2
<p>Photoacoustic signals generated for PA amplitude image excited with a 460 nm LED (<b>a</b>), 530 nm LED (<b>b</b>), 590 nm LED (<b>c</b>), and 620 nm LED (<b>d</b>) (reproduced from Ref. [<a href="#B17-micromachines-15-01007" class="html-bibr">17</a>]).</p> Full article ">Figure 3
<p>The spectral sensitivity of PZT (<b>A</b>) and cMUT (<b>B</b>) as a function of the angle (reproduced from Ref. [<a href="#B31-micromachines-15-01007" class="html-bibr">31</a>]). (<b>C</b>) US and PA images of rat rectum with PMN-PT/epoxy 1-3 composite, PMN-PT, and PZT composite (reproduced from Ref. [<a href="#B33-micromachines-15-01007" class="html-bibr">33</a>]). (<b>D</b>) (<b>a</b>) The reconstructed PA image with 64-, 128-, and 256-element transducer. (<b>b</b>) PA amplitude diagram of vessel along the radial direction. (<b>c</b>) PA amplitude diagram of vessel along the transversal direction (reproduced from Ref. [<a href="#B41-micromachines-15-01007" class="html-bibr">41</a>]).</p> Full article ">Figure 4
<p>(<b>A</b>) Optical absorption coefficient of principal tissue chromophores (reproduced from Ref. [<a href="#B91-micromachines-15-01007" class="html-bibr">91</a>]). (<b>B</b>) The schematic illustration of the CPQ nano-probe activated by MMPs. The conjugated Black Hole Quencher 3 (BHQ3)–peptide–CuS could be cleaved after exposure to MMPs so that the BHQ3 could be released from nanoparticles (reproduced from Ref. [<a href="#B79-micromachines-15-01007" class="html-bibr">79</a>]). (<b>C</b>) Schematic diagram of synthesized silver nanoplates with rounded and more stable tips (reproduced from Ref. [<a href="#B82-micromachines-15-01007" class="html-bibr">82</a>]). (<b>D</b>) Schematic illustration of the preparation of cRGD-PDI NPs and specifical mechanism for lighting early thrombus (reproduced from Ref. [<a href="#B83-micromachines-15-01007" class="html-bibr">83</a>]). (<b>E</b>) Schematic depiction of biodegradable gold nanoparticles. The contrast agent is generated by small AuNPs incorporated into a biodegradable PCPP to achieve diagnostic potential as well as be degraded in vivo into harmless byproducts for excretion after some period (reproduced from Ref. [<a href="#B84-micromachines-15-01007" class="html-bibr">84</a>]).</p> Full article ">Figure 5
<p>(<b>A</b>) PA images and photographs of skin with pigmentation and depigmentation in epidermal structures (reproduced from Ref. [<a href="#B106-micromachines-15-01007" class="html-bibr">106</a>]). (<b>B</b>) PA images and photographs of PWS skin and normal skin (reproduced from Ref. [<a href="#B106-micromachines-15-01007" class="html-bibr">106</a>]). (<b>C</b>) In vivo PA/US images of the human forearm obtained with 40, 21, and 15 MHz frequency transducer probes at 1064 nm wavelength. (<b>a</b>) Photograph of forearm skin from the subject. Fused PA/US imaging acquired with 40 (<b>b</b>), 21 (<b>c</b>), and 15 (<b>d</b>) MHz frequency transducer probes, as well as corresponding (Maximum Intensity Projection) MIP images through the PA volumes of the human forearm (reproduced from Ref. [<a href="#B107-micromachines-15-01007" class="html-bibr">107</a>]). (<b>D</b>) Schematic illustration and PAM image of chicken breast piece with crossing hairs inserted ~1 mm below the surface. The resolution of hairs is ~15 dB SNR (reproduced from Ref. [<a href="#B108-micromachines-15-01007" class="html-bibr">108</a>]). (<b>E</b>) Photoacoustic/ultrasound images of a human proximal interphalangeal joint in sagittal and transverse planes. On the right side, the anatomical structures are indicated by ultrasound imaging (reproduced from Ref. [<a href="#B112-micromachines-15-01007" class="html-bibr">112</a>]).</p> Full article ">Figure 6
<p>(<b>A</b>) Cross-sectional images of IVPA and IVUS and merged images of IVPA-US (reproduced from Ref. [<a href="#B116-micromachines-15-01007" class="html-bibr">116</a>]). (<b>B</b>) Histopathology stained with special dye and magnified images of lipid deposition site (reproduced from Ref. [<a href="#B116-micromachines-15-01007" class="html-bibr">116</a>]). (<b>C</b>) PA images of a normal vessel by utilizing single-element (<b>a</b>) and dual-element (<b>b</b>) transducer as well as distribution of PA amplitude along the dashed line in (<b>a</b>,<b>b</b>). PA images of a normal vessel (<b>c</b>) and an atherosclerotic plaque (<b>d</b>) as well as corresponding bright-field optical images of a normal vessel and an atherosclerotic plaque. (<b>e</b>–<b>h</b>) Lipid-rich plaques in the atherosclerotic vessel sample stained with oil red (reproduced from Ref. [<a href="#B117-micromachines-15-01007" class="html-bibr">117</a>]).</p> Full article ">Figure 7
<p>(<b>A</b>) (<b>a</b>,<b>b</b>) Histological results for the normal cervical tissue and tissue lesion, (<b>c</b>) tissue image corresponding to the DMAP images, and (<b>d</b>) Depth Maximum Amplitude Projection (DMAP) image (reproduced from Ref. [<a href="#B118-micromachines-15-01007" class="html-bibr">118</a>]). (<b>B</b>) (<b>a</b>)A clear anatomical view is produced by combining photoacoustic-based cell-specific targeting with ultrasound imaging, (<b>b</b>) Imaging setup including the ultrasound probe and fiber illumination inserted through the urethra (reproduced from Ref. [<a href="#B67-micromachines-15-01007" class="html-bibr">67</a>]). (<b>C</b>) (<b>a</b>) anatomy of thyroid gland including cardiovascular and respiratory system. (<b>b</b>) PA image of the left thyroid lobe of volunteer. The vascular features of skin [<a href="#B71-micromachines-15-01007" class="html-bibr">71</a>,<a href="#B124-micromachines-15-01007" class="html-bibr">124</a>], muscles, and within the thyroid lobe [<a href="#B125-micromachines-15-01007" class="html-bibr">125</a>] are shown through leveling and normalizing from 0 to 1. (<b>c</b>) Ultrasound cross-sections of the left thyroid lobe. The superimposed areas in color represent directional power Doppler signals. C: carotid; T: thyroid; Tr: trachea; s: sternocleidomastoid muscle; m: infrahyoid muscle (reproduced from Ref. [<a href="#B122-micromachines-15-01007" class="html-bibr">122</a>]).</p> Full article ">Figure 8
<p>(<b>A</b>) PAM image of the vascular on a porcine ovary and corresponding photograph of the porcine ovary. The normalized PA amplitude is indicated by color bar (reproduced from Ref. [<a href="#B108-micromachines-15-01007" class="html-bibr">108</a>]). (<b>B</b>) PA image and fused 3D volume overlay (<b>c</b>) of vasculature system from freshly excised liver tissue using low-frequency (10–30 MHz) (<b>a</b>) and high-frequency (30–90 MHz) (<b>b</b>) detection (reproduced from Ref. [<a href="#B10-micromachines-15-01007" class="html-bibr">10</a>]). (<b>C</b>) Imaging of pig esophagus ex vivo. (<b>a</b>) Volumetric PA image of esophagus sample. (<b>b</b>) PA image of the region of cross-sectional esophagus wall in the dotted box corresponding to figure (<b>a</b>). (<b>c</b>) Histological image with the different layers of esophagus wall. EP: epithelium; M, mucosa; LP, lamina propria; MM, muscularis mucosa; MP, muscularis propria; SM, submucosa. (<b>d</b>) PA image of the different layers in the dotted box corresponding to figure (<b>b</b>). (<b>e</b>) Vasculature of the different esophageal layers revealed by anti-CD31 immunostaining. (<b>f</b>)The stained histological image of the different esophageal layers and corresponding to PA image of different layers. (reproduced from Ref. [<a href="#B129-micromachines-15-01007" class="html-bibr">129</a>]). (<b>D</b>) The microvascular distribution of lower lip during the healing of an ulcer wound. Row 1 in (<b>a</b>–<b>f</b>) presents ORPAM MAP images of ulcer wound. ORPAM B-scans of lip along the dashed white lines in row 1 are shown in row 2 (<b>a</b>–<b>f</b>). OCT B-scans are shown in row 3 (<b>a</b>–<b>f</b>) (reproduced from Ref. [<a href="#B131-micromachines-15-01007" class="html-bibr">131</a>]).</p> Full article ">Figure 9
<p>Brain blood oxygenation stimulated by carbon dioxide. (<b>A</b>–<b>C</b>) Deoxy-hemoglobin pseudocolor images from a single animal at different time points. (<b>D</b>–<b>F</b>) The darker blue represents an increase in deoxidation. The corresponding oxy-hemoglobin is in red. (<b>G</b>) shows a combination of oxy- and deoxy-hemoglobin signals corresponding to B and E. (<b>H</b>,<b>I</b>) The change in oxy- and deoxy-hemoglobin signals with time (reproduced from Ref. [<a href="#B133-micromachines-15-01007" class="html-bibr">133</a>]).</p> Full article ">Figure 10
<p>(<b>A</b>) Photoacoustic B-scan image of the beating heart in an athymic nude mouse. The preliminary image of cardiac structures is depicted, including blood vessels and the skin surface (reproduced from Ref. [<a href="#B135-micromachines-15-01007" class="html-bibr">135</a>]). (<b>B</b>) Photograph of the mouse ear showing blood vessels (<b>a</b>) and corresponding PA images (<b>b</b>,<b>c</b>). (<b>c</b>) is an enlarged region of the white line box in (<b>b</b>). Red blood cells are presented by the white arrows (reproduced from Ref. [<a href="#B136-micromachines-15-01007" class="html-bibr">136</a>]). (<b>C</b>) (<b>a</b>) MAP photoacoustic image of subcutaneous blood vessels in the upper dorsal region of rat. (<b>b</b>) The photograph from the dermal side of excised skin with transmission illumination corresponding to (<b>a</b>). A–E is the area enclosed by major blood vessels (reproduced from Ref. [<a href="#B138-micromachines-15-01007" class="html-bibr">138</a>]). (<b>D</b>) In vivo 3D photoacoustic images of the upper dorsal region of rat (reproduced from Ref. [<a href="#B138-micromachines-15-01007" class="html-bibr">138</a>]). (<b>E</b>) (<b>a</b>) The intravital whole-body imaging of mice after inoculating the tumor for a period of time. (<b>b</b>) The diagram of photoacoustic signals, which is obtained by scanning along two black dashed lines (reproduced from Ref. [<a href="#B139-micromachines-15-01007" class="html-bibr">139</a>]).</p> Full article ">
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Integrated Photonic Devices Integrated with 2D Materials: Advances and Applications
Guest Editors: Jiayang Wu, Yuning ZhangDeadline: 15 August 2024
Special Issue in
Micromachines
Smart Precision Manufacturing and Metrology
Guest Editors: Benny Cheung, Jizhou LiDeadline: 15 August 2024
Special Issue in
Micromachines
Advances in Polymer-Based Materials and Fabrication Processes for Microfluidic Applications II
Guest Editors: Vanessa F. Cardoso, Senentxu Lanceros-MendezDeadline: 15 August 2024
Topical Collections
Topical Collection in
Micromachines
Micromixers: Analysis, Design and Fabrication
Collection Editor: Kwang-Yong Kim
Topical Collection in
Micromachines
Piezoelectric Transducers: Materials, Devices and Applications
Collection Editor: Jose Luis Sanchez-Rojas
Topical Collection in
Micromachines
Micro/Nanoscale Electrokinetics
Collection Editors: Xiangchun Xuan, Rodrigo Martinez-Duarte