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Micromachines
Volume 13
Issue 10
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Micromachines, Volume 13, Issue 10 (October 2022) – 244 articles

Cover Story (view full-size image): A novel core–shell dual-gate nanowire-structure-based single-transistor neuron with excitatory–inhibitory switching, threshold voltage tuning, and myelination functions was realized. This multi-functional neuron device can contribute to the construction of high-density monolithic SNN hardware combined with the vertical synapse MOSFET devices. View this paper
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14 pages, 6094 KiB  
Article
Thermo-Mechanical Reliability Study of Through Glass Vias in 3D Interconnection
by Jin Zhao, Zuohuan Chen, Fei Qin and Daquan Yu
Micromachines 2022, 13(10), 1799; https://doi.org/10.3390/mi13101799 - 21 Oct 2022
Cited by 10 | Viewed by 5776
Abstract
Three-dimensional (3D) interconnection technology based on glass through vias (TGVs) has been used to integrate passive devices, and optoelectronic devices due to its superior electrical qualities, outstanding mechanical stability, and lower cost. Nevertheless, the performance and reliability of the device will be impacted [...] Read more.
Three-dimensional (3D) interconnection technology based on glass through vias (TGVs) has been used to integrate passive devices, and optoelectronic devices due to its superior electrical qualities, outstanding mechanical stability, and lower cost. Nevertheless, the performance and reliability of the device will be impacted by the thermal stress brought on by the mismatch of the coefficient of thermal expansion among multi-material structures and the complicated structure of TGV. This paper focuses on thermal stress evolution in different geometric and material parameters and the development of a controlled method for filling polymers in TGV interconnected structures. In addition, a numerical study based on the finite element (FE) model has been conducted to analyze the stress distribution of the different thicknesses of TGV-Cu. Additionally, a TGV interconnected structure model with a polymer buffer layer is given to solve the crack problem appearing at the edge of RDL. Meanwhile, after practical verification, in comparison to the experimental results, the FE model was shown to be highly effective and accurate for predicting the evolution of stress, and several recommendations were made to alleviate stress-related reliability concerns. An improved manufacturing process flow for the TGV interconnected structure was proposed and verified as feasible to address the RDL crack issue based on the aforementioned research. It provides helpful information for the creation of highly reliable TGV connection structures. Full article
(This article belongs to the Special Issue Advanced Packaging for Microsystem Applications)
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<p>Three-dimensional interconnection structure with TGV.</p> Full article ">Figure 2
<p>TGV package failure mode after temperature cycling.</p> Full article ">Figure 3
<p>The failure mode of thermo-mechanically induced vertical cracks are observed.</p> Full article ">Figure 4
<p>TGV delamination in the condition of opposing thermal stresses.</p> Full article ">Figure 5
<p>The 3D TGV structure model.</p> Full article ">Figure 6
<p>Effect of Cu thickness in TGV on stress evolution.</p> Full article ">Figure 7
<p>Effect of RDL thickness on the wafer on stress evolution.</p> Full article ">Figure 8
<p>Stress distribution of the Cu-filled via on TC.</p> Full article ">Figure 9
<p>The 3D FE model. (<b>a</b>) FE model of A structure. (<b>b</b>) Cross-sectional image of A structure.</p> Full article ">Figure 10
<p>(<b>a</b>) FE model of B structure. (<b>b</b>) Cross-sectional image of B structure.</p> Full article ">Figure 11
<p>(<b>a</b>,<b>b</b>) denote the effect of different PI types and thicknesses on stresses in A and B structure, respectively.</p> Full article ">Figure 12
<p>Effect of glass CTE on stress.</p> Full article ">Figure 13
<p>(<b>a</b>) Top view of a high-density array of TGVs. (<b>b</b>) Cross-sectional image of TGV with the specific size.</p> Full article ">Figure 14
<p>Process flow of TGV full filling. (<b>a</b>) wafer preparation, (<b>b</b>) TGV formation, (<b>c</b>) full side plating, (<b>d</b>) annealing and CMP, (<b>e</b>) PVD and photolithography, (<b>f</b>) plating RDL, (<b>g</b>) photoresist strip and Cu/Ti etch, (<b>h</b>) passivation formation.</p> Full article ">Figure 15
<p>The cross sectional SEM view of TGVs with Cu full filling and RDL layer.</p> Full article ">Figure 16
<p>Process flow of TGV conformal filling. (<b>a</b>) Incoming glass wafer, (<b>b</b>) TGV formation, (<b>c</b>) PVD, (<b>d</b>) RDL lithography, (<b>e</b>) Cu conformal filling, (<b>f</b>) photoresist and seed layer by wet etch, (<b>g</b>) dry film lamination.</p> Full article ">Figure 17
<p>Cross-sectional SEM image of TGV metallization.</p> Full article ">Figure 18
<p>The manufacturing process flow of TGV interconnection structure by laminating a thin polymer film for a buffer layer.</p> Full article ">
13 pages, 2250 KiB  
Article
Electrochemical Testing of a New Polyimide Thin Film Electrode for Stimulation, Recording, and Monitoring of Brain Activity
by Samuel Ong, Aura Kullmann, Steve Mertens, Dave Rosa and Camilo A Diaz-Botia
Micromachines 2022, 13(10), 1798; https://doi.org/10.3390/mi13101798 - 21 Oct 2022
Cited by 2 | Viewed by 2015
Abstract
Subdural electrode arrays are used for monitoring cortical activity and functional brain mapping in patients with seizures. Until recently, the only commercially available arrays were silicone-based, whose thickness and lack of conformability could impact their performance. We designed, characterized, manufactured, and obtained FDA [...] Read more.
Subdural electrode arrays are used for monitoring cortical activity and functional brain mapping in patients with seizures. Until recently, the only commercially available arrays were silicone-based, whose thickness and lack of conformability could impact their performance. We designed, characterized, manufactured, and obtained FDA clearance for 29-day clinical use (510(k) K192764) of a new thin-film polyimide-based electrode array. This study describes the electrochemical characterization undertaken to evaluate the quality and reliability of electrical signal recordings and stimulation of these new arrays. Two testing paradigms were performed: a short-term active soak with electrical stimulation and a 29-day passive soak. Before and after each testing paradigm, the arrays were evaluated for their electrical performance using Electrochemical Impedance Spectroscopy (EIS), Cyclic Voltammetry (CV) and Voltage Transients (VT). In all tests, the impedance remained within an acceptable range across all frequencies. The different CV curves showed no significant changes in shape or area, which is indicative of stable electrode material. The electrode polarization remained within appropriate limits to avoid hydrolysis. Full article
(This article belongs to the Special Issue Progress and Challenges of Implantable Neural Interfaces)
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<p>(<b>a</b>) Picture of a 1 × 4 strip, tail, and connector. (<b>b</b>) High magnification of the electrode contacts. (<b>c</b>) 5× magnification of the connector.</p> Full article ">Figure 2
<p>Schematic of testing paradigms. E-Chem tests consisted of EIS, CV, and VT.</p> Full article ">Figure 3
<p>EIS plots before and after short-term electrochemical testing. Impedance magnitude (left Y scale) and impedance phase (right Y scale) are plotted as a function of frequency. The red and blue lines are impedance magnitude measurements made before and after the electrochemical testing, respectively. The dashed lines represent all data recorded, and the solid lines are the averages of the respective category.</p> Full article ">Figure 4
<p>CV plots before and after short-term electrochemical testing. The dashed red and blue lines represent measurements made before and after electrical stimulation, respectively. The solid red and blue lines are the averages of the values before and after electrical stimulation, respectively.</p> Full article ">Figure 5
<p>VT plot of one set of pulses at a charge density of 30 µC/cm<sup>2</sup> after short-term electrochemical testing.</p> Full article ">Figure 6
<p>Visual inspection of electrodes. Selected images of electrode contacts pre- and post-electrochemical testing on the left (<b>a</b>,<b>c</b>) and right (<b>b</b>,<b>d</b>), respectively. The top images (<b>a</b>,<b>b</b>) are from short-term electrochemical testing, and the bottom images (<b>c</b>,<b>d</b>) are from long-term electrochemical testing. The contact is 3 mm, and the magnification is 5×.</p> Full article ">Figure 7
<p>EIS plots before and after long-term electrochemical testing. Impedance magnitude (left Y scale) and impedance phase (right Y scale) are plotted as a function of frequency. The red and blue lines are impedance magnitude and phase measurements made before and after soak and electrical stimulation, respectively. The dashed lines represent all data recorded, and the solid lines are the averages of the respective category.</p> Full article ">Figure 8
<p>CV plots before and after long-term electrochemical testing. The dashed red and blue lines represent measurements made before and after soak an eletrical stimulation, respectively. The solid red and blue lines are the averages of the values before and after soak and electrical stimulation, respectively, respectively.</p> Full article ">Figure 9
<p>VT plot of one set of pulses at a charge density of 30 µC/cm<sup>2</sup> after long-term electrochemical testing.</p> Full article ">
7 pages, 1647 KiB  
Article
Suppression of the Electrical Crosstalk of Planar-Type High-Density InGaAs Detectors with a Guard Hole
by Jiaxin Zhang, Wei Wang, Haifeng Ye, Runyu Huang, Zepeng Hou, Chen Liu, Weilin Zhao, Yunxue Li, Xu Ma and Yanli Shi
Micromachines 2022, 13(10), 1797; https://doi.org/10.3390/mi13101797 - 21 Oct 2022
Cited by 1 | Viewed by 1686
Abstract
The resolution of InGaAs FPA detectors is degraded by the electrical crosstalk, which is especially severe in high–density FPAs. We propose a guard-hole structure to suppress the electrical crosstalk in a planar-type 640 × 512 15 μm InGaAs short wavelength infrared FPA detector. [...] Read more.
The resolution of InGaAs FPA detectors is degraded by the electrical crosstalk, which is especially severe in high–density FPAs. We propose a guard-hole structure to suppress the electrical crosstalk in a planar-type 640 × 512 15 μm InGaAs short wavelength infrared FPA detector. For comparison, the frequently used guard ring is also prepared according to the same processing. The calculation results show that the electrical crosstalk with a guard hole is suppressed from 13.4% to 4.5%, reducing by 66%, while the electrical crosstalk with a guard ring is suppressed to 0.4%. Furthermore, we discuss the effects of the guard ring and the guard hole on the dark current, quantum efficiency, and detectivity. Experimental results show the detector with a guard-hole structure has higher performance compared with the detector with a guard-ring structure, the dark current density is reduced by 60%, the QE is increased by 64.5%, and the detectivity is increased by 1.36 times, respectively. The guard-hole structure provides a novel suppression method for the electrical crosstalk of high-density InGaAs detectors. Full article
(This article belongs to the Special Issue Terahertz and Infrared Metamaterial Devices)
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<p>(<b>a</b>) After the SiN etching of the guard-hole structure. (<b>b</b>) After the SiN etching of the guard-ring structure. (<b>c</b>) After the P-metal deposition of the guard-hole structure. (<b>d</b>) After the P-metal deposition of the guard-ring structure.</p> Full article ">Figure 2
<p>(<b>a</b>) scatter diagram of Inoperable pixels. (<b>b</b>) Response gray value of electrical crosstalk of inoperable pixel. (<b>c</b>) The schematic diagram of electrical crosstalk of inoperable pixel.</p> Full article ">Figure 3
<p>(<b>a</b>) Response grayscale of the detector with a guard hole; (<b>b</b>) Response grayscale of the detector with a guard ring.</p> Full article ">Figure 4
<p>Schematic of suppression effect of electrical crosstalk of two structures. (<b>a</b>) Guard-ring structure. (<b>b</b>) Guard-hole structure.</p> Full article ">Figure 5
<p>Dark current density of two structures.</p> Full article ">
12 pages, 5301 KiB  
Article
Origami Inspired Laser Scanner
by Yu-Shin Wu and Shao-Kang Hung
Micromachines 2022, 13(10), 1796; https://doi.org/10.3390/mi13101796 - 21 Oct 2022
Viewed by 2051
Abstract
Diverse origami techniques and various selections of paper open new possibilities to create micromachines. By folding paper, this article proposes an original approach to build laser scanners, which manipulate optical beams precisely and realize valuable applications, including laser marking, cutting, engraving, and displaying. [...] Read more.
Diverse origami techniques and various selections of paper open new possibilities to create micromachines. By folding paper, this article proposes an original approach to build laser scanners, which manipulate optical beams precisely and realize valuable applications, including laser marking, cutting, engraving, and displaying. A prototype has been designed, implemented, actuated, and controlled. The experimental results demonstrate that the angular stroke, repeatability, full scale settling time, and resonant frequency are 20°, 0.849 m°, 330 ms, 68 Hz, respectively. Its durability, more than 35 million cycles, shows the potential to carry out serious tasks. Full article
(This article belongs to the Special Issue Origami Devices: Design and Application)
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<p>(<b>a</b>) Neutral position, (<b>b</b>) limit positions, and (<b>c</b>) kinematic diagram of the theoretical four-bar mechanism. (<b>d</b>) Limit positions and (<b>d</b>) kinematic diagram of the realistic four-bar mechanism with 18° hard stopper to avoid mechanical singularity.</p> Full article ">Figure 2
<p>(<b>a</b>) Schematic diagram and (<b>b</b>) photograph of the proposed origami laser galvanometers.</p> Full article ">Figure 3
<p>(<b>a</b>) Positive and (<b>b</b>) negative tilting angles with a corresponding sensor signals.</p> Full article ">Figure 4
<p>(<b>a</b>) The same magnet-sensor gap with different sensor-sensor distance. (<b>b</b>) The same sensor-sensor gap with different magnet-sensor gap.</p> Full article ">Figure 5
<p>A snapshot captured by Tracker program, which analyses the motion of the tilting mirror.</p> Full article ">Figure 6
<p>The block diagram the proposed system.</p> Full article ">Figure 7
<p>(<b>a</b>) Spectrums of the proposed system. (<b>b</b>) Origami hinges are softened along with increasing operation cycles.</p> Full article ">Figure 8
<p>Characterization of the origami galvanometer. (<b>a</b>) Scanning angle versus driving frequency. (<b>b</b>) Scanning angle versus driving current.</p> Full article ">Figure 9
<p>(<b>a</b>) Step-train response and (<b>b</b>) steady state error of the classic PD controller.</p> Full article ">Figure 10
<p>Control gains are adaptively changed with the target angle.</p> Full article ">Figure 11
<p>(<b>a</b>) Step-train response and (<b>b</b>) steady state error of the variable gain PID controller.</p> Full article ">Figure 12
<p>(<b>a</b>) Full scale regulation response of the proposed system. (<b>b</b>) The detailed view of settling time.</p> Full article ">Figure 13
<p>The concept of the 2D origami galvanometer with an optical sensing system.</p> Full article ">
22 pages, 6085 KiB  
Article
Strategy for Fast Decision on Material System Suitability for Continuous Crystallization Inside a Slug Flow Crystallizer
by Anne Cathrine Kufner, Adrian Krummnow, Andreas Danzer and Kerstin Wohlgemuth
Micromachines 2022, 13(10), 1795; https://doi.org/10.3390/mi13101795 - 21 Oct 2022
Cited by 7 | Viewed by 2046
Abstract
There is an increasing focus on two-phase flow in micro- or mini-structured apparatuses for various manufacturing and measurement instrumentation applications, including the field of crystallization as a separation technique. The slug flow pattern offers salient features for producing high-quality products, since narrow residence [...] Read more.
There is an increasing focus on two-phase flow in micro- or mini-structured apparatuses for various manufacturing and measurement instrumentation applications, including the field of crystallization as a separation technique. The slug flow pattern offers salient features for producing high-quality products, since narrow residence time distribution of liquid and solid phases, intensified mixing and heat exchange, and an enhanced particle suspension are achieved despite laminar flow conditions. Due to its unique features, the slug flow crystallizer (SFC) represents a promising concept for small-scale continuous crystallization achieving high-quality active pharmaceutical ingredients (API). Therefore, a time-efficient strategy is presented in this study to enable crystallization of a desired solid product in the SFC as quickly as possible and without much experimental effort. This strategy includes pre-selection of the solvent/solvent mixture using heuristics, verifying the slug flow stability in the apparatus by considering the static contact angle and dynamic flow behavior, and modeling the temperature-dependent solubility in the supposed material system using perturbed-chain statistical associating fluid theory (PC-SAFT). This strategy was successfully verified for the amino acids l-alanine and l-arginine and the API paracetamol for binary and ternary systems and, thus, represents a general approach for using different material systems in the SFC. Full article
(This article belongs to the Special Issue Droplet-Based Microfluidics: Design, Fabrication and Applications)
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<p><math display="inline"><semantics> <mi>Θ</mi> </semantics></math><sub>stat</sub> for the respective solvents is shown. The grey marked area indicates the region in which <math display="inline"><semantics> <mi>Θ</mi> </semantics></math><sub>stat</sub> measurements were not possible (<math display="inline"><semantics> <mi>Θ</mi> </semantics></math><sub>stat</sub> &lt; 20°) with the method described before in <a href="#sec4dot1-micromachines-13-01795" class="html-sec">Section 4.1</a>. The green area (<math display="inline"><semantics> <mi>Θ</mi> </semantics></math><sub>stat</sub> ≥ 90°) marks the <math display="inline"><semantics> <mi>Θ</mi> </semantics></math><sub>stat</sub> at which a non-wetting behavior is expected, and a stable slug flow might be generated.</p> Full article ">Figure 2
<p>Schematic setup for the validation of solvent suitability for slug flow crystallization.</p> Full article ">Figure 3
<p>Images of slugs at the end of the apparatus (<span class="html-italic">L</span> = 7.5 m) during operation with different solvents in an FEP tubing. The liquid and gas flow rates were set to <span class="html-italic">Q</span> = 10 mL min<sup>−1</sup> each. The experiments were conducted at ambient temperature (<math display="inline"><semantics> <mi>ϑ</mi> </semantics></math><sub>amb</sub> <math display="inline"><semantics> <mo>≈</mo> </semantics></math> 22 °C).</p> Full article ">Figure 4
<p>Calculated <span class="html-italic">Ca</span> numbers for the tested solvents in the SFC. The calculation was performed for the operating parameters based on the slug flow stability experiments at liquid and gas flow rates of <span class="html-italic">Q</span> = 10 mL min<sup>−1</sup> each and a ambient temperature of <math display="inline"><semantics> <mi>ϑ</mi> </semantics></math><sub>amb</sub> <math display="inline"><semantics> <mo>≈</mo> </semantics></math> 22 °C. The green area marks the dry pattern slug flow range according to the limit of <span class="html-italic">Ca</span> &lt; 10<sup>−3</sup>.</p> Full article ">Figure 5
<p>Images of saturated Arg/water (<b>top</b>) and APAP/water (<b>bottom</b>) slugs at the end of the apparatus (<span class="html-italic">L</span><sub>tubing</sub> = 7.5 m) during operation inside an FEP tubing of SFC. The liquid and gas flow rates were set to <span class="html-italic">Q</span> = 10 mL min<sup>−1</sup> each. The experiments were conducted at ambient temperature (<math display="inline"><semantics> <mi>ϑ</mi> </semantics></math><sub>amb</sub> <math display="inline"><semantics> <mo>≈</mo> </semantics></math> 22 °C).</p> Full article ">Figure 6
<p>Solubilities of Ala (gray), Arg (blue), and APAP (green) in water (<b>a</b>) and ethanol (<b>b</b>) at 0.1 MPa: Down-pointing triangles, diamonds, circles, up-pointing triangles, and stars depict measured solubilities in water from An et al. [<a href="#B61-micromachines-13-01795" class="html-bibr">61</a>], Grosse Daldrup et al. [<a href="#B74-micromachines-13-01795" class="html-bibr">74</a>], Amend and Helgeseon [<a href="#B75-micromachines-13-01795" class="html-bibr">75</a>], Granberg et al. [<a href="#B76-micromachines-13-01795" class="html-bibr">76</a>], and Grant et al. [<a href="#B42-micromachines-13-01795" class="html-bibr">42</a>]. Hexagons, squares, and left-pointing triangles denote solubility measurements in ethanol from An et al. [<a href="#B61-micromachines-13-01795" class="html-bibr">61</a>], Granberg et al. [<a href="#B53-micromachines-13-01795" class="html-bibr">53</a>], and Matsuda et al. [<a href="#B77-micromachines-13-01795" class="html-bibr">77</a>]. Pentagons and right-pointing triangles are measurements in water and in ethanol performed in this work, respectively. The solid lines are modeled solubility lines using PC-SAFT.</p> Full article ">Figure 7
<p>Ternary phase diagram of Ala/water/ethanol at 0.1 MPa with compositions given in mass fractions: Solubility lines were predicted in this work using PC-SAFT, and symbols denote solubility measurements from An et al. [<a href="#B61-micromachines-13-01795" class="html-bibr">61</a>]. The arrow indicates the direction of increasing temperature from 10 °C to 20 °C, 30 °C, 40 °C, and 50 °C.</p> Full article ">Figure 8
<p>The <span class="html-italic">Ca</span> number is plotted against the <math display="inline"><semantics> <mi>Θ</mi> </semantics></math><sub>stat</sub> for different EtOH/water compositions and volume flow rates. Delineations for the dry pattern are shown via the black dashed lines based on the literature (<b>a</b>) and based on the observations in this work (<b>b</b>). The green area marks the dry pattern, the white area the transition, and the gray area the wet region. The latter is unsuitable for crystallization in the SFC.</p> Full article ">Figure 9
<p>Depiction of the slug flow obtained in the experiments for evaluating the slug shape for different compositions of ethanol/water mixtures at a total volumetric flow rate of <span class="html-italic">Q</span><sub>tot</sub> = 20 mL min<sup>−1</sup> at ambient temperature (<math display="inline"><semantics> <mi>ϑ</mi> </semantics></math><sub>amb</sub> <math display="inline"><semantics> <mo>≈</mo> </semantics></math> 22 °C).</p> Full article ">
14 pages, 3153 KiB  
Article
A Refined Hot Melt Printing Technique with Real-Time CT Imaging Capability
by Kirsty Muldoon, Zeeshan Ahmad, Yu-Chuan Su, Fan-Gang Tseng, Xing Chen, James A. D. McLaughlin and Ming-Wei Chang
Micromachines 2022, 13(10), 1794; https://doi.org/10.3390/mi13101794 - 21 Oct 2022
Cited by 3 | Viewed by 2040
Abstract
Personalised drug delivery systems with the ability to offer real-time imaging and control release are an advancement in diagnostic and therapeutic applications. This allows for a tailored drug dosage specific to the patient with a release profile that offers the optimum therapeutic effect. [...] Read more.
Personalised drug delivery systems with the ability to offer real-time imaging and control release are an advancement in diagnostic and therapeutic applications. This allows for a tailored drug dosage specific to the patient with a release profile that offers the optimum therapeutic effect. Coupling this application with medical imaging capabilities, real-time contrast can be viewed to display the interaction with the host. Current approaches towards such novelty produce a drug burst release profile and contrasting agents associated with side effects as a result of poor encapsulation of these components. In this study, a 3D-printed drug delivery matrix with real-time imaging is engineered. Polycaprolactone (PCL) forms the bulk structure and encapsulates tetracycline hydrochloride (TH), an antibiotic drug and Iron Oxide Nanoparticles (IONP, Fe3O4), a superparamagnetic contrasting agent. Hot melt extrusion (HME) coupled with fused deposition modelling (FDM) is utilised to promote the encapsulation of TH and IONP. The effect of additives on the formation of micropores (10–20 µm) on the 3D-printed surface was investigated. The high-resolution process demonstrated successful encapsulation of both bioactive and nano components to present promising applications in drug delivery systems, medical imaging and targeted therapy. Full article
(This article belongs to the Special Issue Feature Papers of Micromachines in Biology and Biomedicine 2022)
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<p>SEM images of 3D-printed PCL at (<b>a</b>) 100 °C, (<b>b</b>) 110 °C, (<b>c</b>) 120 °C and (<b>d</b>) 130 °C. Distribution of average size for (<b>e</b>) fiber diameter and (<b>f</b>) void distance at various temperatures.</p> Full article ">Figure 2
<p>SEM images of 3D-printed PCL at (<b>a</b>) 4.5 bar, (<b>b</b>) 5.0 bar, (<b>c</b>) 5.5 bar and (<b>d</b>) 6.0 bar. Distribution of average measurement for (<b>e</b>) fiber diameter and (<b>f</b>) void distance at various pressures.</p> Full article ">Figure 3
<p>SEM images of 3D-printed (<b>a</b>) sample 1, (<b>b</b>) sample 2 and (<b>c</b>) sample 3 with insets of surface morphology. Distribution of average size of (<b>d</b>) fiber diameter and (<b>e</b>) void distance.</p> Full article ">Figure 4
<p>Characterization of samples. (<b>a</b>) FTIR of each component of the samples and 3D-printed sample and (<b>b</b>) EDX of 3D-printed sample.</p> Full article ">Figure 5
<p>Analysis on 3D-printed samples. (<b>a</b>) Water contact angle results of 3D-printed samples and PCL, and (<b>b</b>) tensile test.</p> Full article ">Figure 6
<p>Images, MicroCT scan and histogram of particle distribution of 3D-printed (<b>a</b>) PCL and (<b>b</b>) PCL with Fe<sub>3</sub>O<sub>4</sub>. (<b>c</b>) Seven-day drug release profile.</p> Full article ">Figure 6 Cont.
<p>Images, MicroCT scan and histogram of particle distribution of 3D-printed (<b>a</b>) PCL and (<b>b</b>) PCL with Fe<sub>3</sub>O<sub>4</sub>. (<b>c</b>) Seven-day drug release profile.</p> Full article ">
13 pages, 2887 KiB  
Article
A High-Precision Method of Stiffness Axes Identification for Axisymmetric Resonator Gyroscopes
by Junhao Xiong, Kaiyong Yang, Tao Xia, Jingyu Li, Yonglei Jia, Yunfeng Tao, Yao Pan and Hui Luo
Micromachines 2022, 13(10), 1793; https://doi.org/10.3390/mi13101793 - 21 Oct 2022
Cited by 1 | Viewed by 1551
Abstract
Axisymmetric resonators are key elements of Coriolis vibratory gyroscopes (CVGs). The performance of a CVG is closely related to the stiffness and damping symmetry of its resonator. The stiffness symmetry of a resonator can be effectively improved by electrostatic tuning or mechanical trimming, [...] Read more.
Axisymmetric resonators are key elements of Coriolis vibratory gyroscopes (CVGs). The performance of a CVG is closely related to the stiffness and damping symmetry of its resonator. The stiffness symmetry of a resonator can be effectively improved by electrostatic tuning or mechanical trimming, both of which need an accurate knowledge of the azimuth angles of the two stiffness axes of the resonator. Considering that the motion of a non-ideal axisymmetric resonator can be decomposed as two principal oscillations with two different natural frequencies along two orthogonal stiffness axes, this paper introduces a novel high-precision method of stiffness axes identification. The method is based on measurements of the phase difference between the signals detected at two orthogonal sensing electrodes when an axisymmetric resonator is released from all the control forces of the force-to-rebalance mode and from different initial pattern angles. Except for simplicity, our method works with the eight-electrodes configuration, in no need of additional electrodes or detectors. Furthermore, the method is insensitive to the variation of natural frequencies and operates properly in the cases of either large or small frequency splits. The introduced method is tested on a resonator gyroscope, and two stiffness axes azimuth angles are obtained with a resolution better than 0.1°. A comparison of the experimental results and theoretical model simulations confirmed the validity of our method. Full article
(This article belongs to the Special Issue MEMS Inertial Sensors)
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<p>Schematic diagram of an imperfect axisymmetric resonator. Two red squares represent the orthogonal sensing electrodes. The dashed red line represents the high-frequency stiffness axis with an azimuth angle of <math display="inline"><semantics> <msub> <mi>θ</mi> <mi>ω</mi> </msub> </semantics></math>, and the dashed blue line corresponds to the low-frequency stiffness axis with an azimuth angle equal to <math display="inline"><semantics> <mrow> <msub> <mi>θ</mi> <mi>ω</mi> </msub> <mo>+</mo> <msup> <mn>45</mn> <mo>°</mo> </msup> </mrow> </semantics></math>. The green ellipse exhibits deformation of the resonator with the pattern angle <math display="inline"><semantics> <mi>β</mi> </semantics></math>.</p> Full article ">Figure 2
<p>The vibration of the resonator in (<b>a</b>) can be decomposed as a vector superposition of vibration depicted in (<b>b</b>,<b>c</b>), with <math display="inline"><semantics> <mrow> <mi>α</mi> <mo>=</mo> <mi>β</mi> <mo>−</mo> <msub> <mi>θ</mi> <mi>ω</mi> </msub> </mrow> </semantics></math>. The length of the arrows in these plots is a representation of the oscillation amplitudes. (<b>d</b>) is the corresponding ordinary Euclid orthogonal coordinate representation.</p> Full article ">Figure 3
<p>A numerical simulation of output signals <math display="inline"><semantics> <msub> <mi>S</mi> <mi>x</mi> </msub> </semantics></math> and <math display="inline"><semantics> <msub> <mi>S</mi> <mi>y</mi> </msub> </semantics></math> and amplitudes <math display="inline"><semantics> <msub> <mi>A</mi> <mi>x</mi> </msub> </semantics></math> and <math display="inline"><semantics> <msub> <mi>A</mi> <mi>y</mi> </msub> </semantics></math>. Set <math display="inline"><semantics> <mrow> <msub> <mi>θ</mi> <mi>ω</mi> </msub> <mo>=</mo> <msup> <mn>30</mn> <mo>°</mo> </msup> </mrow> </semantics></math>, <math display="inline"><semantics> <mrow> <mi>β</mi> <mo>=</mo> <msup> <mn>26</mn> <mo>°</mo> </msup> </mrow> </semantics></math>, <math display="inline"><semantics> <mrow> <mi>f</mi> <mo>=</mo> <mn>7000</mn> </mrow> </semantics></math> Hz, <math display="inline"><semantics> <mrow> <mi>d</mi> <mi>f</mi> <mo>=</mo> <mn>4</mn> </mrow> </semantics></math> mHz. The thin blue lines show <math display="inline"><semantics> <msub> <mi>S</mi> <mi>x</mi> </msub> </semantics></math> and <math display="inline"><semantics> <msub> <mi>S</mi> <mi>y</mi> </msub> </semantics></math>, and the thick red and green lines are for <math display="inline"><semantics> <msub> <mi>A</mi> <mi>x</mi> </msub> </semantics></math> and <math display="inline"><semantics> <msub> <mi>A</mi> <mi>y</mi> </msub> </semantics></math>. Plot (<b>d</b>) is an amplification of plot (<b>a</b>) with a smaller time scale.</p> Full article ">Figure 4
<p><math display="inline"><semantics> <msub> <mi>A</mi> <mi>x</mi> </msub> </semantics></math> and <math display="inline"><semantics> <msub> <mi>A</mi> <mi>y</mi> </msub> </semantics></math> as functions of time for different pattern vibration directions in two cases of <math display="inline"><semantics> <msub> <mi>θ</mi> <mi>ω</mi> </msub> </semantics></math>: <math display="inline"><semantics> <mrow> <msub> <mi>θ</mi> <mi>ω</mi> </msub> <mo>=</mo> <msup> <mn>30</mn> <mo>°</mo> </msup> </mrow> </semantics></math> and <math display="inline"><semantics> <mrow> <msub> <mi>θ</mi> <mi>ω</mi> </msub> <mo>=</mo> <msup> <mn>70</mn> <mo>°</mo> </msup> </mrow> </semantics></math>. Black, green, cyan, red, and blue lines correspond to <math display="inline"><semantics> <mrow> <mi>α</mi> <mo>=</mo> <msup> <mn>0</mn> <mo>°</mo> </msup> </mrow> </semantics></math>, <math display="inline"><semantics> <msup> <mn>2</mn> <mo>°</mo> </msup> </semantics></math>, <math display="inline"><semantics> <msup> <mn>4</mn> <mo>°</mo> </msup> </semantics></math>, <math display="inline"><semantics> <mrow> <mo>−</mo> <msup> <mn>2</mn> <mo>°</mo> </msup> </mrow> </semantics></math>, <math display="inline"><semantics> <mrow> <mo>−</mo> <msup> <mn>4</mn> <mo>°</mo> </msup> </mrow> </semantics></math>, respectively.</p> Full article ">Figure 5
<p>Details of signal processing to obtain the amplitudes <math display="inline"><semantics> <msub> <mi>A</mi> <mi>x</mi> </msub> </semantics></math> and the demodulated signal <math display="inline"><semantics> <msub> <mi>S</mi> <mrow> <mi>y</mi> <mi>Q</mi> </mrow> </msub> </semantics></math>.</p> Full article ">Figure 6
<p>The demodulated quantity <math display="inline"><semantics> <msub> <mover accent="true"> <mi>S</mi> <mo>˙</mo> </mover> <mrow> <mi>y</mi> <mi>Q</mi> </mrow> </msub> </semantics></math> as function of pattern angle <math display="inline"><semantics> <mi>β</mi> </semantics></math>, with <math display="inline"><semantics> <msub> <mi>θ</mi> <mi>ω</mi> </msub> </semantics></math> set to <math display="inline"><semantics> <mrow> <mo>−</mo> <msup> <mn>15</mn> <mo>°</mo> </msup> </mrow> </semantics></math>.</p> Full article ">Figure 7
<p>(<b>a</b>) Photograph of the experimental setup with an HRG and a circuits system. (<b>b</b>) Physical structure of the HRG.</p> Full article ">Figure 8
<p>Block diagram of the HRG with the circuits system. The PCB part shows a sketch of functions for both the buffer board and the mixed-signal board. The FPGA + ARM part corresponds to the digital control board.</p> Full article ">Figure 9
<p>Results of theoretical simulations and experiments of <math display="inline"><semantics> <msub> <mi>A</mi> <mi>x</mi> </msub> </semantics></math>. In plot (<b>a</b>,<b>b</b>), the black, green, cyan, red, and blue lines correspond to <math display="inline"><semantics> <mrow> <mi>β</mi> <mo>−</mo> <msub> <mi>β</mi> <mn>0</mn> </msub> <mo>=</mo> <msup> <mn>0</mn> <mo>°</mo> </msup> </mrow> </semantics></math>, <math display="inline"><semantics> <msup> <mn>5</mn> <mo>°</mo> </msup> </semantics></math>, <math display="inline"><semantics> <msup> <mn>10</mn> <mo>°</mo> </msup> </semantics></math>, <math display="inline"><semantics> <mrow> <mo>−</mo> <msup> <mn>5</mn> <mo>°</mo> </msup> </mrow> </semantics></math>, <math display="inline"><semantics> <mrow> <mo>−</mo> <msup> <mn>10</mn> <mo>°</mo> </msup> </mrow> </semantics></math>, respectively. In plot (<b>c</b>,<b>d</b>), the black, green, cyan, red, and blue lines correspond to <math display="inline"><semantics> <mrow> <mi>β</mi> <mo>−</mo> <msub> <mi>β</mi> <mn>1</mn> </msub> <mo>=</mo> <msup> <mn>0</mn> <mo>°</mo> </msup> </mrow> </semantics></math>, <math display="inline"><semantics> <msup> <mn>5</mn> <mo>°</mo> </msup> </semantics></math>, <math display="inline"><semantics> <msup> <mn>10</mn> <mo>°</mo> </msup> </semantics></math>, <math display="inline"><semantics> <mrow> <mo>−</mo> <msup> <mn>5</mn> <mo>°</mo> </msup> </mrow> </semantics></math>, <math display="inline"><semantics> <mrow> <mo>−</mo> <msup> <mn>10</mn> <mo>°</mo> </msup> </mrow> </semantics></math>, respectively.</p> Full article ">Figure 10
<p>Theoretical results and experimental results of <math display="inline"><semantics> <msub> <mi>S</mi> <mrow> <mi>y</mi> <mi>Q</mi> </mrow> </msub> </semantics></math>. In plot (<b>a</b>,<b>b</b>), the black, green, cyan, red, and blue lines correspond to <math display="inline"><semantics> <mrow> <mi>β</mi> <mo>−</mo> <msub> <mi>β</mi> <mn>0</mn> </msub> <mo>=</mo> <msup> <mn>0</mn> <mo>°</mo> </msup> </mrow> </semantics></math>, <math display="inline"><semantics> <msup> <mn>5</mn> <mo>°</mo> </msup> </semantics></math>, <math display="inline"><semantics> <msup> <mn>10</mn> <mo>°</mo> </msup> </semantics></math>, <math display="inline"><semantics> <mrow> <mo>−</mo> <msup> <mn>5</mn> <mo>°</mo> </msup> </mrow> </semantics></math>, <math display="inline"><semantics> <mrow> <mo>−</mo> <msup> <mn>10</mn> <mo>°</mo> </msup> </mrow> </semantics></math>, respectively. In plot (<b>c</b>,<b>d</b>), the black, green, cyan, red, and blue lines correspond to <math display="inline"><semantics> <mrow> <mi>β</mi> <mo>−</mo> <msub> <mi>β</mi> <mn>1</mn> </msub> <mo>=</mo> <msup> <mn>0</mn> <mo>°</mo> </msup> </mrow> </semantics></math>, <math display="inline"><semantics> <msup> <mn>5</mn> <mo>°</mo> </msup> </semantics></math>, <math display="inline"><semantics> <msup> <mn>10</mn> <mo>°</mo> </msup> </semantics></math>, <math display="inline"><semantics> <mrow> <mo>−</mo> <msup> <mn>5</mn> <mo>°</mo> </msup> </mrow> </semantics></math>, <math display="inline"><semantics> <mrow> <mo>−</mo> <msup> <mn>10</mn> <mo>°</mo> </msup> </mrow> </semantics></math>, respectively.</p> Full article ">
31 pages, 9249 KiB  
Review
MXene/Ferrite Magnetic Nanocomposites for Electrochemical Supercapacitor Applications
by Arun Thirumurugan, Ananthakumar Ramadoss, Shanmuga Sundar Dhanabalan, Sathish-Kumar Kamaraj, Natarajan Chidhambaram, Suyambrakasam Gobalakrishnan, Carolina Venegas Abarzúa, Yerko Alejandro Reyes Caamaño, Rednam Udayabhaskar and Mauricio J. Morel
Micromachines 2022, 13(10), 1792; https://doi.org/10.3390/mi13101792 - 20 Oct 2022
Cited by 9 | Viewed by 4053
Abstract
MXene has been identified as a new emerging material for various applications including energy storage, electronics, and bio-related due to its wider physicochemical characteristics. Further the formation of hybrid composites of MXene with other materials makes them interesting to utilize in multifunctional applications. [...] Read more.
MXene has been identified as a new emerging material for various applications including energy storage, electronics, and bio-related due to its wider physicochemical characteristics. Further the formation of hybrid composites of MXene with other materials makes them interesting to utilize in multifunctional applications. The selection of magnetic nanomaterials for the formation of nanocomposite with MXene would be interesting for the utilization of magnetic characteristics along with MXene. However, the selection of the magnetic nanomaterials is important, as the magnetic characteristics of the ferrites vary with the stoichiometric composition of metal ions, particle shape and size. The selection of the electrolyte is also important for electrochemical energy storage applications, as the electrolyte could influence the electrochemical performance. Further, the external magnetic field also could influence the electrochemical performance. This review briefly discusses the synthesis method of MXene, and ferrite magnetic nanoparticles and their composite formation. We also discussed the recent progress made on the MXene/ferrite nanocomposite for potential applications in electrochemical supercapacitor applications. The possibility of magnetic field-assisted supercapacitor applications with electrolyte and electrode materials are discussed. Full article
(This article belongs to the Special Issue Sustainable Materials for Energy and Environmental Applications)
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Figure 1

Figure 1
<p>(<bold>a</bold>) MAX phase structures and their associated MXenes. Reproduced with permission from [<xref ref-type="bibr" rid="B5-micromachines-13-01792">5</xref>] Copyright (2013) John Wiley &amp; Sons. (<bold>b</bold>) Usual MXene compositions and structures. Reproduced with permission from [<xref ref-type="bibr" rid="B21-micromachines-13-01792">21</xref>] Copyright (2021) John Wiley &amp; Sons. (<bold>c</bold>) Experimentally discovered MXenes: structural and molecular formula. Reproduced with permission from [<xref ref-type="bibr" rid="B22-micromachines-13-01792">22</xref>] Copyright (2019) Elsevier.</p> Full article ">Figure 2
<p>Schematic process of etching and exfoliation process of MXene from MAS phase. Reproduced with permission from [<xref ref-type="bibr" rid="B35-micromachines-13-01792">35</xref>] Copyright (2012) American Chemical Society.</p> Full article ">Figure 3
<p>SEM micrograph of exfoliated MXene (<bold>i</bold>) (Ti<sub>3</sub>C<sub>2</sub>) with (<bold>a</bold>) LiF (<bold>b</bold>)NaF, (<bold>c</bold>) KF (<bold>d</bold>) NH<sub>4</sub>F, in HCl, and (<bold>ii</bold>) (Ti<sub>2</sub>C) with (<bold>a</bold>) LiF (<bold>b</bold>)NaF, (<bold>c</bold>) KF (<bold>d</bold>) NH4F, in HCl. Reproduced with permission from [<xref ref-type="bibr" rid="B47-micromachines-13-01792">47</xref>] Copyright (2017) Elsevier.</p> Full article ">Figure 4
<p>Diagram illustrating the interaction between a NaOH solution and Ti<sub>3</sub>AlC<sub>2</sub> under various circumstances. ((<bold>a</bold>) At low temperatures, Al (oxide) hydroxides obstruct the extraction of Al. (<bold>b</bold>) In the presence of high temperatures and low NaOH conc, certain Al (oxide) hydroxides dissolve in NaOH. (<bold>c</bold>) Based on the Bayer mechanism, dissolving the Al (oxide) hydroxides in NaOH is aided by high temperatures and higher concentrations of NaOH), (<bold>b</bold>–<bold>d</bold>) SEM, TEM, and HRTEM micrograph of prepared MXene. Reproduced (modified) with permission from [<xref ref-type="bibr" rid="B44-micromachines-13-01792">44</xref>] Copyright (2018) John Wiley &amp; Sons.</p> Full article ">Figure 5
<p>TEM micrograph of Mn-Zn ferrite nanocrystals collected from the reaction mixture at 260 °C, 280 °C, and 300 °C following aging for 0, 20, and 40 min. (<bold>A</bold>) spherical (<bold>B</bold>) cubical, and (<bold>C</bold>) starlike. (<bold>D</bold>) Evolution of the shape of starlike nanocrystals shown schematically. Reproduced with permission from [<xref ref-type="bibr" rid="B62-micromachines-13-01792">62</xref>] Copyright (2013) American Chemical Society.</p> Full article ">Figure 6
<p>TEM, HRTEM micrograph and size distribution of (<bold>a</bold>–<bold>c</bold>) sphere-CoFe<sub>2</sub>O<sub>4</sub> (<bold>d</bold>–<bold>f</bold>) cubic-CoFe<sub>2</sub>O, and (<bold>g</bold>–<bold>i</bold>) hexagonal-CoFe<sub>2</sub>O. Reproduced with permission from [<xref ref-type="bibr" rid="B63-micromachines-13-01792">63</xref>] Copyright (2019) Elsevier.</p> Full article ">Figure 7
<p>Schematic diagram for the different morphology formation processes of α-Fe<sub>2</sub>O<sub>3</sub> and Ni-ferrite. Reproduced with permission from [<xref ref-type="bibr" rid="B64-micromachines-13-01792">64</xref>] Copyright (2015) Royal Society of Chemistry.</p> Full article ">Figure 8
<p>(<bold>a</bold>) Schematic synthesis process of Mxene/Fe<sub>3</sub>O<sub>4</sub> nanocomposite through Solvothermal process. Reproduced with permission from [<xref ref-type="bibr" rid="B81-micromachines-13-01792">81</xref>]. (<bold>b</bold>) Schematic synthesis process of Alk-MXene composites with Fe<sub>3</sub>O<sub>4</sub> through ultrasonic treatment. Reproduced with permission from [<xref ref-type="bibr" rid="B29-micromachines-13-01792">29</xref>] copyright (2022) John Wiley and Sons.</p> Full article ">Figure 9
<p>TEM micrographs of (<bold>A</bold>) MXene and (<bold>B</bold>) MXene/Fe<sub>3</sub>O<sub>4</sub> nanocomposite. Reproduced with permission from [<xref ref-type="bibr" rid="B27-micromachines-13-01792">27</xref>] Copyright (2022) John Wiley and Sons.</p> Full article ">Figure 10
<p>(<bold>i</bold>) XRD pattern of (<bold>a</bold>) Co ferrite, (<bold>b</bold>) MXene/Co-ferrite, (<bold>c</bold>) comparison pattern, and (<bold>d</bold>) magnified at lower angle, and (<bold>ii</bold>) SEM micrograph of (<bold>a</bold>,<bold>b</bold>) Co-ferrite, (<bold>c</bold>) MXene and (<bold>d</bold>) MXene/Co-ferrite nanocomposite. Reproduced with permission from [<xref ref-type="bibr" rid="B24-micromachines-13-01792">24</xref>] Copyright (2020) American Chemical Society.</p> Full article ">Figure 11
<p>(<bold>a</bold>) CV, (<bold>b</bold>) GCD curves, (<bold>c</bold>) Cs vs. current density, (<bold>d</bold>) cyclic stability and (<bold>e</bold>) specific capacity vs. current density. Reproduced with permission from [<xref ref-type="bibr" rid="B24-micromachines-13-01792">24</xref>] Copyright (2020) American Chemical Society.</p> Full article ">Figure 12
<p>TEM Micrograph of (<bold>a</bold>) MXene, and (<bold>b</bold>) MXene/ Fe<sub>3</sub>O<sub>4.</sub></p> Full article ">Figure 13
<p>(<bold>a</bold>) CV, (<bold>b</bold>) GCD, (<bold>c</bold>) Cs vs. current density, and (<bold>d</bold>) EIS curves of MXene/Fe<sub>3</sub>O<sub>4</sub>.</p> Full article ">Figure 14
<p>Schematic setup for the measurement of effect of external magnetic field. Reproduced (modified) from [<xref ref-type="bibr" rid="B143-micromachines-13-01792">143</xref>] Copyright (2021) with permission from Elsevier.</p> Full article ">Figure 15
<p>The impact of magnetic field on various aqueous electrolyte’s conductivity, viscosity, and electrochemical properties. The MCF variation with scan rates under the magnetic field of (<bold>A</bold>) 876 Oe, and (<bold>B</bold>) 1786 Oe, (<bold>C</bold>) Variation in the conductivity with magnetic field, and (<bold>D</bold>)Variation in the viscosity with magnetic field. Reproduced (modified) from [<xref ref-type="bibr" rid="B143-micromachines-13-01792">143</xref>] Copyright (2021) with permission from Elsevier.</p> Full article ">Figure 16
<p>Influence of a magnetic field on the electrochemical properties of KOH electrolytes at various concentrations. Variation in the MCF values at a scan rate of (<bold>A</bold>) 10 mV/s, (<bold>B</bold>) 200 mV/s, (<bold>C</bold>) Variation in the conductivity with KOH concentrations under different magnetic field, (<bold>D</bold>) Variation in the viscosity with KOH concentrations under different magnetic field, (<bold>E</bold>) Variation of I<sub>lim</sub> with KOH concentrations, and (<bold>F</bold>) Diffusion coefficient of KOH with various concentrations. Reproduced (modified) from [<xref ref-type="bibr" rid="B143-micromachines-13-01792">143</xref>] Copyright (2021) with permission from Elsevier.</p> Full article ">Figure 17
<p>CV and GCD curves of (<bold>a</bold>,<bold>c</bold>) Fe<sub>3</sub>O<sub>4</sub> and (<bold>b</bold>,<bold>d</bold>) Fe<sub>3</sub>O<sub>4</sub>/RGO with and without magnetic field. Reproduced with permission from [<xref ref-type="bibr" rid="B144-micromachines-13-01792">144</xref>] Copyright (2018) IOP Publishing.</p> Full article ">Figure 18
<p>CV curves of (<bold>a</bold>,<bold>b</bold>) Fe<sub>2</sub>O<sub>3</sub> and (<bold>c</bold>,<bold>d</bold>) Fe<sub>2</sub>O<sub>3</sub>/graphene. Reproduced with permission from [<xref ref-type="bibr" rid="B145-micromachines-13-01792">145</xref>] Copyright (2012) Royal Society of Chemistry.</p> Full article ">Figure 19
<p>Energy density vs. (<bold>a</bold>) power density and (<bold>b</bold>) current density of graphene and Fe<sub>2</sub>O<sub>3</sub>/graphene composite. Reproduced with permission from [<xref ref-type="bibr" rid="B145-micromachines-13-01792">145</xref>] Copyright (2012) Royal Society of Chemistry.</p> Full article ">Figure 20
<p>Schematic process diagram for the magnetic field assisted supercapacitor application with MXene/Ferrite magnetic nanocomposites.</p> Full article ">
18 pages, 8571 KiB  
Article
Dynamic Adaptive Display System for Electrowetting Displays Based on Alternating Current and Direct Current
by Shixiao Li, Yijian Xu, Zhiyu Zhan, Pengyuan Du, Linwei Liu, Zikai Li, Huawei Wang and Pengfei Bai
Micromachines 2022, 13(10), 1791; https://doi.org/10.3390/mi13101791 - 20 Oct 2022
Cited by 4 | Viewed by 1637
Abstract
As a representative of the new reflective display technology, electrowetting display (EWD) technology can be used as a video playback display device due to its fast response characteristics. Direct current (DC) driving brings excellent reflectivity, but static images cannot be displayed continually due [...] Read more.
As a representative of the new reflective display technology, electrowetting display (EWD) technology can be used as a video playback display device due to its fast response characteristics. Direct current (DC) driving brings excellent reflectivity, but static images cannot be displayed continually due to charge trapping, and it can cause afterimages when playing a dynamic video due to contact angle hysteresis. Alternating current (AC) driving brings a good dynamic video refresh ability to EWDs, but that can cause flickers. In this paper, a dynamic adaptive display model based on thin film transistor-electrowetting display (TFT-EWD) was proposed. According to the displayed image content, the TFT-EWD display driver was dynamically adjusted by AC and DC driving models. A DC hybrid driving model was suitable for static image display, which could effectively suppress oil backflow and achieve static image display while ensuring high reflectivity. A source data non-polarized model (SNPM) is an AC driving model which was suitable for dynamic video display and was proposed at the same time. Compared with DC driving, it could obtain smooth display performance with a loss of about 10 absorbance units (A.U.) of reflective luminance, which could solve the flicker problem. With the DC hybrid driving model, the ability to continuously display static images could be obtained with a loss of 2 (A.U.) of luminance. Under the AC driving in SNPM, the reflected luminance was as high as 67 A.U., which was 8 A.U. higher than the source data polarized model (SPM), and it was closer to the reflected luminance under DC driving. Full article
(This article belongs to the Special Issue Advances in Optoelectronic Devices)
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Figure 1

Figure 1
<p>Pixel structure and operating principle of EWDs. (<b>A</b>) Pixel state when the EWD is closed. (<b>B</b>) Pixel states when the EWD is turned on. (<b>C</b>) Picture of pixel state when the EWD is closed. (<b>D</b>) Picture of pixel state when the EWD is turned on.</p> Full article ">Figure 2
<p>Dynamic adaptive display of the discriminant process diagram. (<b>A</b>) Diagram of the static image discrimination process. (<b>B</b>) Dynamic video discrimination process diagram.</p> Full article ">Figure 3
<p>Schematic diagram of the DC hybrid driving waveform.</p> Full article ">Figure 4
<p>Waveform diagram of AC driving model. (<b>A</b>) Diagram of the source polarization model (SPM). (<b>B</b>) Diagram of the source non-polarized model (SNPM).</p> Full article ">Figure 5
<p>Schematic diagram of source polarization EWD model. (<b>A</b>) In TFT-EWD, Top ITO and TFT were connected to <math display="inline"><semantics> <mrow> <mi>V</mi> <mi>c</mi> <mi>o</mi> <mi>m</mi> <mi>m</mi> <mi>o</mi> <mi>n</mi> </mrow> </semantics></math> signal and <math display="inline"><semantics> <mrow> <mi>V</mi> <mi>s</mi> <mi>o</mi> <mi>u</mi> <mi>r</mi> <mi>c</mi> <mi>e</mi> </mrow> </semantics></math> signal respectively. (<b>B</b>) When <math display="inline"><semantics> <mrow> <mi>V</mi> <mi>c</mi> <mi>o</mi> <mi>m</mi> <mi>m</mi> <mi>o</mi> <mi>n</mi> </mrow> </semantics></math> was positive, <math display="inline"><semantics> <mrow> <mi>V</mi> <mi>s</mi> <mi>o</mi> <mi>u</mi> <mi>r</mi> <mi>c</mi> <mi>e</mi> </mrow> </semantics></math> was negative. (<b>C</b>) When <math display="inline"><semantics> <mrow> <mi>V</mi> <mi>c</mi> <mi>o</mi> <mi>m</mi> <mi>m</mi> <mi>o</mi> <mi>n</mi> </mrow> </semantics></math> was positive, <math display="inline"><semantics> <mrow> <mi>V</mi> <mi>s</mi> <mi>o</mi> <mi>u</mi> <mi>r</mi> <mi>c</mi> <mi>e</mi> </mrow> </semantics></math> was negative.</p> Full article ">Figure 6
<p>Schematic diagram of source non-polarization model. (<b>A</b>) In TFT-EWD, pixels of top ITO and TFT were connected to <math display="inline"><semantics> <mrow> <mi>V</mi> <mi>c</mi> <mi>o</mi> <mi>m</mi> <mi>m</mi> <mi>o</mi> <mi>n</mi> </mrow> </semantics></math> signal and <math display="inline"><semantics> <mrow> <mi>V</mi> <mi>s</mi> <mi>o</mi> <mi>u</mi> <mi>r</mi> <mi>c</mi> <mi>e</mi> </mrow> </semantics></math> signal, respectively. (<b>B</b>) When <math display="inline"><semantics> <mrow> <mi>V</mi> <mi>c</mi> <mi>o</mi> <mi>m</mi> <mi>m</mi> <mi>o</mi> <mi>n</mi> </mrow> </semantics></math> was positive, <math display="inline"><semantics> <mrow> <mi>V</mi> <mi>s</mi> <mi>o</mi> <mi>u</mi> <mi>r</mi> <mi>c</mi> <mi>e</mi> </mrow> </semantics></math> was positive. (<b>C</b>) When <math display="inline"><semantics> <mrow> <mi>V</mi> <mi>c</mi> <mi>o</mi> <mi>m</mi> <mi>m</mi> <mi>o</mi> <mi>n</mi> </mrow> </semantics></math> was positive, <math display="inline"><semantics> <mrow> <mi>V</mi> <mi>s</mi> <mi>o</mi> <mi>u</mi> <mi>r</mi> <mi>c</mi> <mi>e</mi> </mrow> </semantics></math> was positive.</p> Full article ">Figure 7
<p>Reverse the common poles diagram of different frames.</p> Full article ">Figure 8
<p>Dynamic adaptive display testing system physical map.</p> Full article ">Figure 9
<p>EWDs testing platform physical map. (<b>A</b>) Aperture ratio testing platform. (<b>B</b>) Reflection luminance testing platform.</p> Full article ">Figure 10
<p>Reflectivity under each DC driving model.</p> Full article ">Figure 11
<p>Aperture ratio in each DC driving state. (<b>A</b>) +15 V DC driving waveform. (<b>B</b>) +20 V DC driving waveform. (<b>C</b>) −15 V DC driving waveform. (<b>D</b>) −20 V DC driving waveform. (<b>E</b>) +15 V and +20 V mixed DC driving waveform. (<b>F</b>) −15 V and −20 V mixed DC driving waveform.</p> Full article ">Figure 12
<p>DC driving effect of static picture display. (<b>A</b>) +15 V DC driving waveform. (<b>B</b>) +20 V DC driving waveform. (<b>C</b>) −15 V DC driving waveform. (<b>D</b>) −20 V DC driving waveform. (<b>E</b>) +15 V and +20 V mixed DC driving waveform. (<b>F</b>) −15 V and −20 V mixed DC driving waveform.</p> Full article ">Figure 13
<p>Reflected luminance graphs under various AC waveforms. (<b>A</b>) The aperture ratio of each waveform when in SPM. (<b>B</b>) The aperture ratio of each waveform when in SNPM.</p> Full article ">Figure 14
<p>Aperture ratio under different AC driving models. (<b>A</b>) The aperture ratio of +15 V and −15 V AC driving in SPM. (<b>B</b>) The aperture ratio of +15 V and −15 V AC driving in SNPM. (<b>C</b>) The aperture ratio of +15 V and −20 V AC driving in SPM. (<b>D</b>) The aperture ratio of +15 V and −20 V AC driving in SNPM. (<b>E</b>) The aperture ratio of +20 V and −15 V AC driving in SPM. (<b>F</b>) The aperture ratio of +20 V and −15 V AC driving in SNPM. (<b>G</b>) The aperture ratio of +20 V and −20 V AC driving in SPM. (<b>H</b>) The aperture ratio of +20 V and −20 V AC driving in SNPM.</p> Full article ">Figure 15
<p>Display dynamic pictures in the AC driving models.</p> Full article ">Figure 16
<p>The abnormal phenomenon in the experiment. (<b>A</b>) The EWD displays anomaly analysis. (<b>B</b>) Oil splitting.</p> Full article ">Figure A1
<p>The results of the SPM applied under different AC drive waveforms.</p> Full article ">Figure A2
<p>The results of applying the SNPM under different AC drive waveforms.</p> Full article ">
17 pages, 2590 KiB  
Review
Using Chiplet Encapsulation Technology to Achieve Processing-in-Memory Functions
by Wenchao Tian, Bin Li, Zhao Li, Hao Cui, Jing Shi, Yongkun Wang and Jingrong Zhao
Micromachines 2022, 13(10), 1790; https://doi.org/10.3390/mi13101790 - 20 Oct 2022
Cited by 12 | Viewed by 6289
Abstract
With the rapid development of 5G, artificial intelligence (AI), and high-performance computing (HPC), there is a huge increase in the data exchanged between the processor and memory. However, the “storage wall” caused by the von Neumann architecture severely limits the computational performance of [...] Read more.
With the rapid development of 5G, artificial intelligence (AI), and high-performance computing (HPC), there is a huge increase in the data exchanged between the processor and memory. However, the “storage wall” caused by the von Neumann architecture severely limits the computational performance of the system. To efficiently process such large amounts of data and break up the “storage wall”, it is necessary to develop processing-in-memory (PIM) technology. Chiplet combines processor cores and memory chips with advanced packaging technologies, such as 2.5D, 3 dimensions (3D), and fan-out packaging. This improves the quality and bandwidth of signal transmission and alleviates the “storage wall” problem. This paper reviews the Chiplet packaging technology that has achieved the function of PIM in recent years and analyzes some of its application results. First, the research status and development direction of PIM are presented and summarized. Second, the Chiplet packaging technologies that can realize the function of PIM are introduced, which are divided into 2.5D, 3D packaging, and fan-out packaging according to their physical form. Further, the form and characteristics of their implementation of PIM are summarized. Finally, this paper is concluded, and the future development of Chiplet in the field of PIM is discussed. Full article
(This article belongs to the Special Issue Advanced Packaging for Microsystem Applications)
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<p>(<b>a</b>) Von Neuman architecture; (<b>b</b>) performance statistics for each module in the von Neumann architecture.</p> Full article ">Figure 2
<p>(<b>a</b>) “Rome” CPU architecture (reprinted from Ref. [<a href="#B26-micromachines-13-01790" class="html-bibr">26</a>], Copyright 2021, with permission from IEEE); (<b>b</b>) Chiplet-based accelerated processing units (reprinted from Ref. [<a href="#B28-micromachines-13-01790" class="html-bibr">28</a>], Copyright 2017, with permission from IEEE).</p> Full article ">Figure 3
<p>(<b>a</b>) PIM architecture based on Chiplet; (<b>b</b>) Chiplet-based design GPU (reprinted from Ref. [<a href="#B29-micromachines-13-01790" class="html-bibr">29</a>], Copyright 2017, with permission from ACM); (<b>c</b>) Simba Chiplet (reprinted from Ref. [<a href="#B30-micromachines-13-01790" class="html-bibr">30</a>], Copyright 2019, with permission from IEEE).</p> Full article ">Figure 4
<p>(<b>a</b>) CoWoS packaging process (reprinted from Ref. [<a href="#B31-micromachines-13-01790" class="html-bibr">31</a>], Copyright 2017, with permission from IEEE); (<b>b</b>) CoWoS realizes the form of PIM (reprinted from Ref. [<a href="#B33-micromachines-13-01790" class="html-bibr">33</a>], Copyright 2021, with permission from IEEE); (<b>c</b>) NVIDIA GP100 structure (reprinted from Ref. [<a href="#B34-micromachines-13-01790" class="html-bibr">34</a>], Copyright 2017, with permission from IEEE); (<b>d</b>) Virtex<sup>®</sup>UltraScale+™ structure (reprinted from Ref. [<a href="#B35-micromachines-13-01790" class="html-bibr">35</a>], Copyright 2017, with permission from IEEE).</p> Full article ">Figure 5
<p>(<b>a</b>) The physical construction of the EMIB package (reprinted from Ref. [<a href="#B39-micromachines-13-01790" class="html-bibr">39</a>], Copyright 2019, with permission from IEEE); (<b>b</b>) Intel Agilex FPGA structure layout (reprinted from Ref. [<a href="#B40-micromachines-13-01790" class="html-bibr">40</a>], Copyright 2020, with permission from IEEE).</p> Full article ">Figure 6
<p>A diagram depicting the PicoServer (reprinted from Ref. [<a href="#B43-micromachines-13-01790" class="html-bibr">43</a>], Copyright 2006, with permission from ACM).</p> Full article ">Figure 7
<p>Foveros architecture (reprinted from Ref. [<a href="#B47-micromachines-13-01790" class="html-bibr">47</a>], Copyright 2020, with permission from IEEE).</p> Full article ">Figure 8
<p>(<b>a</b>) Co-EMIB 3D Integration Technology (reprinted from Ref. [<a href="#B50-micromachines-13-01790" class="html-bibr">50</a>], Copyright 2020, with permission from IEEE); (<b>b</b>) Ponte Vecchio GPU architecture (reprinted from Ref. [<a href="#B51-micromachines-13-01790" class="html-bibr">51</a>], Copyright 2021, with permission from IEEE).</p> Full article ">Figure 9
<p><b>(a)</b> 3D stacked processor and memory supporting large bandwidth but limited by TSV area increase &amp; thermals; <b>(b)</b> solution of TSV &amp; thermal problem using silicon interposer at the expense of reduced bandwidth and higher power; <b>(c)</b> ODI solution for supporting large bandwidth, good thermal performance and minimal TSV area increase. (reprinted from Ref. [<a href="#B52-micromachines-13-01790" class="html-bibr">52</a>], Copyright 2019, with permission from IEEE).</p> Full article ">Figure 10
<p>(<b>a</b>) FOCoS Technology (reprinted from Ref. [<a href="#B53-micromachines-13-01790" class="html-bibr">53</a>], Copyright 2019, with permission from IEEE); (<b>b</b>) wafer-level packaging using embedded fine-pitch interconnect chips (reprinted from Ref. [<a href="#B54-micromachines-13-01790" class="html-bibr">54</a>], Copyright 2018, with permission from IEEE).</p> Full article ">Figure 11
<p>(<b>a</b>) Apple A10 chip package schematic (reprinted from Ref. [<a href="#B55-micromachines-13-01790" class="html-bibr">55</a>], Copyright 2016, with permission from IEEE); (<b>b</b>) 3D-MiM (MUST-in-MUST) integration technology (reprinted from Ref. [<a href="#B57-micromachines-13-01790" class="html-bibr">57</a>], Copyright 2019, with permission from IEEE).</p> Full article ">Figure 12
<p>(<b>a</b>) Principle of SoIC Technology (reprinted from Ref. [<a href="#B58-micromachines-13-01790" class="html-bibr">58</a>], Copyright 2019, with permission from IEEE); (<b>b</b>) compatible use of SoIC with CoWS and InFO (reprinted from Ref. [<a href="#B33-micromachines-13-01790" class="html-bibr">33</a>], Copyright 2021, with permission from IEEE).</p> Full article ">
17 pages, 1526 KiB  
Review
Developments in FRET- and BRET-Based Biosensors
by Yuexin Wu and Tianyu Jiang
Micromachines 2022, 13(10), 1789; https://doi.org/10.3390/mi13101789 - 20 Oct 2022
Cited by 19 | Viewed by 6932
Abstract
Resonance energy transfer technologies have achieved great success in the field of analysis. Particularly, fluorescence resonance energy transfer (FRET) and bioluminescence resonance energy transfer (BRET) provide strategies to design tools for sensing molecules and monitoring biological processes, which promote the development of biosensors. [...] Read more.
Resonance energy transfer technologies have achieved great success in the field of analysis. Particularly, fluorescence resonance energy transfer (FRET) and bioluminescence resonance energy transfer (BRET) provide strategies to design tools for sensing molecules and monitoring biological processes, which promote the development of biosensors. Here, we provide an overview of recent progress on FRET- and BRET-based biosensors and their roles in biomedicine, environmental applications, and synthetic biology. This review highlights FRET- and BRET-based biosensors and gives examples of their applications with their design strategies. The limitations of their applications and the future directions of their development are also discussed. Full article
(This article belongs to the Special Issue Prospects and Challenges of Biosensors towards Diagnostics of the Diseases and Health Monitoring)
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<p>Principles of FRET and BRET. (<b>a</b>) Schematic representation of the FRET process, where the energy transfers from the donor to the acceptor in proximity. (<b>b</b>) Schematic representation of the BRET process. The donor luciferase oxidizes the substrate, then produces bioluminescence to excite the acceptor.</p> Full article ">Figure 2
<p>FRET- and BRET-based biosensors for biomedical applications. (<b>a</b>) A self-standard ratiometric, highly sensitive FRET platform for detecting exosomes [<a href="#B57-micromachines-13-01789" class="html-bibr">57</a>]. (<b>b</b>) A FRET-based bioassay for the recognition of an epithelial cell adhesion molecule (EpCAM) [<a href="#B58-micromachines-13-01789" class="html-bibr">58</a>]. (<b>c</b>) A folding-based FRET sensor for dopamine [<a href="#B59-micromachines-13-01789" class="html-bibr">59</a>]. (<b>d</b>) A biosensor for the real-time optical tracking of isoleucine in living cells [<a href="#B60-micromachines-13-01789" class="html-bibr">60</a>]. (<b>e</b>) A biosensor based on FRET and catalytic hairpin assembly for the detection of polysialic acid by use of a new DNA aptamer [<a href="#B61-micromachines-13-01789" class="html-bibr">61</a>]. (<b>f</b>) A highly sensitive FRET biosensor for measurement of cGMP in cardiomyocytes and neurons [<a href="#B62-micromachines-13-01789" class="html-bibr">62</a>]. (<b>g</b>) An ICT-FRET integration platform for the real-time monitoring of SO<sub>2</sub> metabolism in cancer cells and tumor models [<a href="#B63-micromachines-13-01789" class="html-bibr">63</a>]. (<b>h</b>) A BRET-based biosensor for point-of-care therapeutic drug monitoring [<a href="#B66-micromachines-13-01789" class="html-bibr">66</a>]. (<b>i</b>) A BRET-based biosensor for detecting antibodies in blood plasma [<a href="#B67-micromachines-13-01789" class="html-bibr">67</a>,<a href="#B68-micromachines-13-01789" class="html-bibr">68</a>,<a href="#B69-micromachines-13-01789" class="html-bibr">69</a>]. (<b>j</b>) A BRET-based biosensor for antibodies detection using intramolecular split luciferase complementation [<a href="#B70-micromachines-13-01789" class="html-bibr">70</a>]. (<b>k</b>) A BRET-based immunosensor for antigens named BRET Q-Body [<a href="#B72-micromachines-13-01789" class="html-bibr">72</a>]. (<b>l</b>) A BRET-based biosensor for NADPH [<a href="#B73-micromachines-13-01789" class="html-bibr">73</a>].</p> Full article ">Figure 3
<p>FRET- and BRET-based biosensors for environmental research. (<b>a</b>) A FRET-based immunosensor for the detection of ochratoxin A in agro-products [<a href="#B88-micromachines-13-01789" class="html-bibr">88</a>]. (<b>b</b>) A FRET-based aptamer biosensor for the detection of aflatoxin B1 in peanut and rice [<a href="#B89-micromachines-13-01789" class="html-bibr">89</a>]. (<b>c</b>) FRET-based sensors for organophosphate pesticide determination [<a href="#B90-micromachines-13-01789" class="html-bibr">90</a>]. (<b>d</b>) A FRET-based biosensor for Hg<sup>2+</sup> in food [<a href="#B91-micromachines-13-01789" class="html-bibr">91</a>]. (<b>e</b>) A FRET-based biosensor for off-on detection of Pb<sup>2+</sup> [<a href="#B92-micromachines-13-01789" class="html-bibr">92</a>]. (<b>f</b>) A FRET-based aptasensor for rapid and ultra-sensitive bacteria detection [<a href="#B93-micromachines-13-01789" class="html-bibr">93</a>].</p> Full article ">
14 pages, 3241 KiB  
Article
Adaptive Feature Extraction for Blood Vessel Segmentation and Contrast Recalculation in Laser Speckle Contrast Imaging
by Eduardo Morales-Vargas, Juan Pablo Padilla-Martinez, Hayde Peregrina-Barreto, Wendy Argelia Garcia-Suastegui and Julio Cesar Ramirez-San-Juan
Micromachines 2022, 13(10), 1788; https://doi.org/10.3390/mi13101788 - 20 Oct 2022
Cited by 2 | Viewed by 1938
Abstract
Microvasculature analysis in biomedical images is essential in the medical area to evaluate diseases by extracting properties of blood vessels, such as relative blood flow or morphological measurements such as diameter. Given the advantages of Laser Speckle Contrast Imaging (LSCI), several studies have [...] Read more.
Microvasculature analysis in biomedical images is essential in the medical area to evaluate diseases by extracting properties of blood vessels, such as relative blood flow or morphological measurements such as diameter. Given the advantages of Laser Speckle Contrast Imaging (LSCI), several studies have aimed to reduce inherent noise to distinguish between tissue and blood vessels at higher depths. These studies have shown that computing Contrast Images (CIs) with Analysis Windows (AWs) larger than standard sizes obtains better statistical estimators. The main issue is that larger samples combine pixels of microvasculature with tissue regions, reducing the spatial resolution of the CI. This work proposes using adaptive AWs of variable size and shape to calculate the features required to train a segmentation model that discriminates between blood vessels and tissue in LSCI. The obtained results show that it is possible to improve segmentation rates of blood vessels up to 45% in high depths (≈900 μm) by extracting features adaptively. The main contribution of this work is the experimentation with LSCI images under different depths and exposure times through adaptive processing methods, furthering the understanding the performance of the different approaches under these conditions. Results also suggest that it is possible to train a segmentation model to discriminate between pixels belonging to blood vessels and those belonging to tissue. Therefore, an adaptive feature extraction method may improve the quality of the features and thus increase the classification rates of blood vessels in LSCI. Full article
(This article belongs to the Special Issue Laser and Optics in Micromachines for Biomedical Applications)
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<p>Experimental setup used to acquire the RSIs in vitro samples.</p> Full article ">Figure 2
<p>Surgical procedure to acquire the in vivo speckle images.</p> Full article ">Figure 3
<p>Adjacency of the analyzed pixels with the cluster centers.</p> Full article ">Figure 4
<p>Comparison of JI obtained with traditional (red) and adaptive feature extraction (blue), performing the classification with a weighted k-NN. Results are grouped by depth to study depth invariance. ANOVA (F-Value = 2413.46, <span class="html-italic">p</span> = 0, <math display="inline"><semantics> <mi>α</mi> </semantics></math> = 0.05).</p> Full article ">Figure 5
<p>Comparison of traditional (red) and adaptive feature extraction (blue), performing the classification with a weighted k-NN with all the exposure times and depths. (<b>a</b>) shows the differences between the adaptive traditional methods in terms of percentage improvements, and (<b>b</b>) shows the results grouped by exposure time at 0 <math display="inline"><semantics> <mrow> <mi mathvariant="sans-serif">μ</mi> <mi mathvariant="normal">m</mi> </mrow> </semantics></math>. ANOVA (F-Value = 22.43, <span class="html-italic">p</span> = 0, <math display="inline"><semantics> <mi>α</mi> </semantics></math> = 0.05).</p> Full article ">Figure 6
<p>Segmentation results: (<b>a</b>) CI of an in vivo image of the used data where the square is the close-up analyzed in (<b>b</b>,<b>c</b>); (<b>b</b>) is the traditional segmentation result, and (<b>c</b>) is the adaptive segmentation results. Pixels in black represent true negatives, white are true positives, red are false positives, and blue are false negatives.</p> Full article ">Figure 7
<p>Comparison of the segmentation results by method for the analyzed depths and variable exposure times: Anisotropic Contrast (aK), Averaged Spatial Contrast (asK), Space Directional Contrast (sdK), Adaptive window Contrast (awK), Spatially Adaptive Windowing Contrast (sawK). ANOVA (F-Value = 27.70, <span class="html-italic">p</span> = 0, <math display="inline"><semantics> <mi>α</mi> </semantics></math> = 0.05).</p> Full article ">Figure 8
<p>Comparison of the segmentation results before and after the reconnection process: (<b>a</b>) CI of an in vivo sample where the square represents a close-up of the (<b>b</b>) output of the segmentation algorithm and (<b>c</b>) the reconnected blood vessel. Pixels in black are true negatives, white are true positives, red are false positives, and blue are false negatives.</p> Full article ">Figure 9
<p>Methodology for the contrast recalculation using adaptively extracted features.</p> Full article ">Figure 10
<p>Slice of a contrast image for contrast image calculated using a traditional (red) and an adaptive approach (blue) for an in vivo image.</p> Full article ">Figure 11
<p>Slice of a CI calculated using a traditional analysis window with <math display="inline"><semantics> <mrow> <mi>d</mi> <mo>=</mo> <mn>5</mn> </mrow> </semantics></math> and by using the multi-scale contrast with the recalculated contrast.</p> Full article ">Figure 12
<p>Comparison of maps sizes for the adaptive processing of LSCI of an in vitro CI with size of <math display="inline"><semantics> <mrow> <mn>344</mn> <mo>×</mo> <mn>329</mn> </mrow> </semantics></math> pixels. The depth of the blood vessel and the adaptive method vary.</p> Full article ">
14 pages, 4908 KiB  
Article
An Adaptive Fusion Attitude and Heading Measurement Method of MEMS/GNSS Based on Covariance Matching
by Wei Sun, Peilun Sun and Jiaji Wu
Micromachines 2022, 13(10), 1787; https://doi.org/10.3390/mi13101787 - 20 Oct 2022
Cited by 5 | Viewed by 1637
Abstract
Aimed at the problem of filter divergence caused by unknown noise statistical characteristics or variable noise characteristics in an MEMS/GNSS integrated navigation system in a dynamic environment, on the basis of revealing the parameter adjustment logic of covariance matching adaptive technology, a fusion [...] Read more.
Aimed at the problem of filter divergence caused by unknown noise statistical characteristics or variable noise characteristics in an MEMS/GNSS integrated navigation system in a dynamic environment, on the basis of revealing the parameter adjustment logic of covariance matching adaptive technology, a fusion adaptive filtering scheme combining innovation-based adaptive estimation (IAE) and the adaptive fading Kalman filter (AFKF) is proposed. By setting two system tuning parameters, for the process noise covariance adaptation loop and the measurement noise covariance adaptation loop, covariance matching is sped up and achieves an effective suppression of filter divergence. The vehicle-mounted experimental results show that the mean square error of the combined attitude error obtained based on the fusion filtering method proposed in this paper is better than 0.5°, and the mean square error of the heading error is better than 1.5°. The results can provide technical support for the continuous extraction of low-cost attitude information from mobile platforms. Full article
(This article belongs to the Special Issue Controls of Micromachines)
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<p>Construction of experimental environment.</p> Full article ">Figure 2
<p>Motion trajectory diagram.</p> Full article ">Figure 3
<p>Accelerometer data and gyroscope data.</p> Full article ">Figure 4
<p>Attitude angle error of measured data.</p> Full article ">Figure 5
<p>PDOP value in the urban experimental environment.</p> Full article ">Figure 6
<p>Test track diagram.</p> Full article ">Figure 7
<p>Accelerometer data and gyroscope data.</p> Full article ">Figure 8
<p>Comparison curve of attitude angle solution.</p> Full article ">Figure 9
<p>Attitude angle error.</p> Full article ">
10 pages, 5440 KiB  
Article
Effect of Layer Orientation and Pore Morphology on Water Transport in Multilayered Porous Graphene
by Chulwoo Park, Ferlin Robinson and Daejoong Kim
Micromachines 2022, 13(10), 1786; https://doi.org/10.3390/mi13101786 - 20 Oct 2022
Viewed by 1746
Abstract
In the present work, the effects on water transport due to the orientation of the layer in the multilayered porous graphene and the different patterns formed when the layer is oriented to some degrees are studied for both circular and non-circular pore configurations. [...] Read more.
In the present work, the effects on water transport due to the orientation of the layer in the multilayered porous graphene and the different patterns formed when the layer is oriented to some degrees are studied for both circular and non-circular pore configurations. Interestingly, the five-layered graphene membrane with a layer separation of 3.5 Å used in this study shows that the water transport through multilayered porous graphene can be augmented by introducing an angle to certain layers of the multilayered membrane system. Full article
(This article belongs to the Special Issue Carbon Nanotube-Based Devices)
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<p>The computational domain.</p> Full article ">Figure 2
<p>Pore shapes and patterns used in the simulation. (<b>a</b>) Circular shaped pore; (<b>b</b>) non-circular shaped pore; (<b>c</b>) representation of base pattern; (<b>d</b>) representation of pattern 1; (<b>e</b>) representation of pattern 2; (<b>f</b>) representation of pattern 3. Angled graphene sheets are represented in cyan color.</p> Full article ">Figure 2 Cont.
<p>Pore shapes and patterns used in the simulation. (<b>a</b>) Circular shaped pore; (<b>b</b>) non-circular shaped pore; (<b>c</b>) representation of base pattern; (<b>d</b>) representation of pattern 1; (<b>e</b>) representation of pattern 2; (<b>f</b>) representation of pattern 3. Angled graphene sheets are represented in cyan color.</p> Full article ">Figure 3
<p>The cumulative molecule (water) passage through multilayered graphene nanopore (<b>a</b>) circular pore with pattern 1 (<b>b</b>) Non-circular pore with pattern 1 (<b>c</b>) circular pore with pattern 2 (<b>d</b>) Non-circular pore with pattern 2 (<b>e</b>) circular pore with pattern 3 (<b>f</b>) Non-circular pore with pattern 3.</p> Full article ">Figure 4
<p>Free energy of occupancy fluctuations of water molecules inside the nanopore (<b>a</b>) circular pore with pattern 1 (<b>b</b>) Non-circular pore with pattern 1 (<b>c</b>) circular pore with pattern 2 (<b>d</b>) Non-circular pore with pattern 2 (<b>e</b>) circular pore with pattern 3 (<b>f</b>) Non-circular pore with pattern 3.</p> Full article ">Figure 5
<p>(<b>a</b>) Radial distribution function (RDF) of water molecules inside the circular pore with pattern 1 (<b>b</b>) density of water molecules inside the circular pore for pattern 1 (<b>c</b>) Radial distribution function (RDF) of water molecules inside the Non−circular pore with pattern 1 (<b>d</b>) density of water molecules inside the Non-circular pore for pattern 1.</p> Full article ">Figure 6
<p>Interaction energy between the carbon atoms of the pore with the oxygen atoms of water molecules and the interaction force along Z−direction for the pattern 1 (<b>a</b>) circular porous membrane (<b>b</b>) non-circular porous membrane.</p> Full article ">
11 pages, 3965 KiB  
Article
Serpentine Micromixers Using Extensional Mixing Elements
by George Tomaras, Chandrasekhar R. Kothapalli and Petru S. Fodor
Micromachines 2022, 13(10), 1785; https://doi.org/10.3390/mi13101785 - 20 Oct 2022
Cited by 5 | Viewed by 2359
Abstract
Computational fluid dynamics modeling was used to characterize the effect of the integration of constrictions defined by the vertices of hyperbolas on the flow structure in microfluidic serpentine channels. In the new topology, the Dean flows characteristic of the pressure-driven fluid motion along [...] Read more.
Computational fluid dynamics modeling was used to characterize the effect of the integration of constrictions defined by the vertices of hyperbolas on the flow structure in microfluidic serpentine channels. In the new topology, the Dean flows characteristic of the pressure-driven fluid motion along curved channels are combined with elongational flows and asymmetric longitudinal eddies that develop in the constriction region. The resulting complex flow structure is characterized by folding and stretching of the fluid volumes, which can promote enhanced mixing. Optimization of the geometrical parameters defining the constriction region allows for the development of an efficient micromixer topology that shows robust enhanced performance across a broad range of Reynolds numbers from Re = 1 to 100. Full article
(This article belongs to the Collection Micromixers: Analysis, Design and Fabrication)
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<p>Velocity field maps along the center plane for: (<b>a</b>) a channel with a rectangular constriction and (<b>b</b>) a channel with a constriction defined by a hyperbolic function, respectively. (<b>c</b>) Corresponding pressure gradient profiles along the two channels, showing lower pressure drops for the same constriction diameter for the hyperbolic design.</p> Full article ">Figure 2
<p>(<b>a</b>) Top view of the geometry of the investigated design; (<b>b</b>) hyperbola defining the constriction of the straight sections between adjacent curves; (<b>c</b>) 3D geometry of the channel investigated.</p> Full article ">Figure 3
<p>(<b>top</b>) Longitudinal cross-section at <span class="html-italic">H/2</span> (middle of the channel) of the magnitude of the velocity map and (<b>bottom</b>) concentration cross-sectional maps along the channel, for: (<b>a</b>) the design with <span class="html-italic">a =</span> 20 μm and <span class="html-italic">b</span> = 1 × <span class="html-italic">a</span>; and (<b>b</b>) the corresponding simple serpentine channel (Reynolds number <span class="html-italic">Re</span> = 20).</p> Full article ">Figure 4
<p>Velocity magnitude and concentration maps for the (<b>a</b>) design with <span class="html-italic">a =</span> 35 μm and <span class="html-italic">b</span> = 2 × <span class="html-italic">a</span>; and (<b>b</b>) the corresponding simple serpentine channel (<span class="html-italic">Re</span> = 20).</p> Full article ">Figure 5
<p>Velocity magnitude and concentration maps for the (<b>a</b>) design with <span class="html-italic">a =</span> 50 μm and <span class="html-italic">b</span> = 3 × <span class="html-italic">a</span>; and (<b>b</b>) the corresponding simple serpentine channel (<span class="html-italic">Re</span> = 20).</p> Full article ">Figure 6
<p>Reynolds number dependence of the mixing index of mixers with: (<b>left</b>) <span class="html-italic">a =</span> 20 μm and <span class="html-italic">b</span> = 1 × <span class="html-italic">a</span>; (<b>middle</b>) <span class="html-italic">a =</span> 35 μm and <span class="html-italic">b</span> = 2 × <span class="html-italic">a</span>; and (<b>right</b>) <span class="html-italic">a =</span> 50 μm and <span class="html-italic">b</span> = 3 × <span class="html-italic">a</span>.</p> Full article ">Figure 7
<p>Stretch rate maps along the longitudinal cross-section of various constricted serpentine channels studied in this work. Insets specify the geometrical parameters of the channels, as well as the maximum value <math display="inline"><semantics> <mrow> <msub> <mover accent="true"> <mi>ε</mi> <mo>˙</mo> </mover> <mrow> <mi>m</mi> <mi>a</mi> <mi>x</mi> </mrow> </msub> </mrow> </semantics></math> of the <math display="inline"><semantics> <mrow> <msub> <mover accent="true"> <mi>ε</mi> <mo>˙</mo> </mover> <mrow> <mi>y</mi> </mrow> </msub> </mrow> </semantics></math> stretch rate observed (<span class="html-italic">Re</span> = 20).</p> Full article ">Figure 8
<p>Streamline plots for: (<b>a</b>) transversal section in a serpentine channel; (<b>b</b>) transversal section in a constricted channel; and (<b>c</b>) longitudinal section in a constricted channel (<span class="html-italic">Re</span> = 40).</p> Full article ">Figure 9
<p>(<b>a</b>) Parametric study of the mixing index dependence on the <span class="html-italic">a</span> and <span class="html-italic">b</span> parameters (<span class="html-italic">Re</span> = 20); (<b>b</b>) increase in the mixing performance relative to simple serpentine designs.</p> Full article ">
12 pages, 1794 KiB  
Article
Phase-Optimized Peristaltic Pumping by Integrated Microfluidic Logic
by Erik M. Werner, Benjamin X. Lam and Elliot E. Hui
Micromachines 2022, 13(10), 1784; https://doi.org/10.3390/mi13101784 - 20 Oct 2022
Cited by 3 | Viewed by 2443
Abstract
Microfluidic droplet generation typically entails an initial stabilization period on the order of minutes, exhibiting higher variation in droplet volume until the system reaches monodisperse production. The material lost during this period can be problematic when preparing droplets from limited samples such as [...] Read more.
Microfluidic droplet generation typically entails an initial stabilization period on the order of minutes, exhibiting higher variation in droplet volume until the system reaches monodisperse production. The material lost during this period can be problematic when preparing droplets from limited samples such as patient biopsies. Active droplet generation strategies such as antiphase peristaltic pumping effectively reduce stabilization time but have required off-chip control hardware that reduces system accessibility. We present a fully integrated device that employs on-chip pneumatic logic to control phase-optimized peristaltic pumping. Droplet generation stabilizes in about a second, with only one or two non-uniform droplets produced initially. Full article
(This article belongs to the Special Issue Microfluidic Technologies for Medical Diagnosis and Global Health)
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<p>Design of integrated controller for droplet generator. (<b>a</b>) An inverter gate is created by attaching high and low resistance channels to opposite sides of a valve. Channels on the top and bottom layers are shown in red and blue, respectively. A top-down valve detail shows dimensions of the valves used in this study (length L = 0.5 mm, width W = 1 mm). Cross-section valve detail shows an open valve (upper) and closed valve (lower) with elastomeric membrane in green (thickness T = 250 µm) and depth of the displacement chamber (depth D = 150 µm). (<b>b</b>) The transfer function of a laser-cut inverter gate produces a sharp non-linear switch in output vacuum as input vacuum is increased (solid line, valve opening) and decreased (dashed line, valve closing). (<b>c</b>) Block diagram of the droplet system. A ring oscillator created from inverter gates synchronizes four peristaltic pumps. (<b>d</b>) Photo of the device generating water-in-oil droplets containing blue and red dye (scale bar = 3 mm).</p> Full article ">Figure 2
<p>Optimizing droplet monodispersity. Distributions of droplet volumes produced by design iterations (<b>a</b>) Version 23: five-inverter two chamber pump, (<b>b</b>) Version 28: three-inverter single chamber pump with capacitors, (<b>c</b>) Version 32: three-inverter single chamber pump with larger capacitors. All distributions were sampled at steady state with <span class="html-italic">N</span> &gt; 40. (<b>d</b>) The total output flow rate produced by the optimized droplet generator (version 32). The peak flow rate (red dashed lines) delivered by each pump cycle increased from 38.9 µL/min to 52.3 µL/min as operating vacuum increased from 25 kPa to 50 kPa.</p> Full article ">Figure 3
<p>Optimizing pump waveform synthesis. (<b>a</b>) Pump operation was monitored with high-speed video. The reflection of incident light from the membrane of each pump valve was used to detect valve state (open or closed). Dashed colored lines show the area of the image analyzed for each valve. Scale bar = 3 mm. (<b>b</b>) Valve detail shows open valves reflect more light back the camera. (<b>c</b>) Time traces of normalized reflected light from each valve from device versions 27 (top) and version 32 (bottom). 1 = valve open (vacuum pressure), 0 = valve closed (atmospheric pressure). Adding large capacitors before and after each row of pump valves (version 32) increased the time required to open each row of valves and the subsequent inverter gate, preventing all pump stages (A, B, and C) from being open simultaneously (shaded rectangle), which resulted in improved pump performance. (<b>d</b>) Illustrations of device versions 27 and 32. Channels in the top and bottom layers are shown in blue and red, respectively.</p> Full article ">Figure 4
<p>Electricity-free droplet generation. (<b>a</b>) A 60 mL locking syringe supplies enough vacuum pressure (blue line) to generate droplets (black circles) for over 10 min. The change in volume is minimal for vacuum pressures greater than 50 kPa. For the first 200.6 s (dashed red line), 465 droplets were produced with a CV &lt; 5% and a mean volume of 16.52 nL. (<b>b</b>) Adding a vacuum regulator to the syringe output can provide a stable vacuum pressure for a short time but produced fewer uniform-sized droplets. In the first 67.4 s, 158 droplets with a mean volume of 21.77 nL were produced with a CV &lt; 5% (dashed red line). In both graphs, the first two droplets generated were omitted from volume calculations to account for system stabilization.</p> Full article ">
18 pages, 5515 KiB  
Article
Hybrid Compliant Musculoskeletal System for Fast Actuation in Robots
by Pieter Wiersinga, Aidan Sleavin, Bart Boom, Thijs Masmeijer, Spencer Flint and Ed Habtour
Micromachines 2022, 13(10), 1783; https://doi.org/10.3390/mi13101783 - 20 Oct 2022
Cited by 3 | Viewed by 2333
Abstract
A nature-inspired musculoskeletal system is designed and developed to examine the principle of nonlinear elastic energy storage–release for robotic applications. The musculoskeletal system architecture consists of elastically rigid segments and hyperelastic soft materials to emulate rigid–soft interactions in limbless vertebrates. The objectives are [...] Read more.
A nature-inspired musculoskeletal system is designed and developed to examine the principle of nonlinear elastic energy storage–release for robotic applications. The musculoskeletal system architecture consists of elastically rigid segments and hyperelastic soft materials to emulate rigid–soft interactions in limbless vertebrates. The objectives are to (i) improve the energy efficiency of actuation beyond that of current pure soft actuators while (ii) producing a high range of motion similar to that of soft robots but with structural stability. This paper proposes a musculoskeletal design that takes advantage of structural segmentation to increase the system’s degrees of freedom, which enhances the range of motion. Our findings show that rigid–soft interactions provide a remarkable increase in energy storage and release and, thus, an increase in the undulation speed. The energy efficiency achieved is approximately 68% for bending the musculoskeletal system from the straight configuration, compared to 2.5–30% efficiency in purely soft actuators. The hybrid compliance of the musculoskeletal system under investigation shows promise for alleviating the need for actuators at each joint in a robot. Full article
(This article belongs to the Special Issue 3D Printed Actuators)
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Graphical abstract

Graphical abstract
Full article ">Figure 1
<p>The snake-inspired musculoskeletal system consists of rigid segments (dark gray) connected with hyperelastic material (transparent sections) at the end of the ribs. Each rigid segment has a socket–disk joint and two ribs on each side. The hyperelastic material provided nonlinear elastic energy storage. The ribs transfer energy between the <math display="inline"><semantics> <mrow> <mo>−</mo> <mi>X</mi> </mrow> </semantics></math> and <span class="html-italic">X</span> sides.</p> Full article ">Figure 2
<p>(<b>a</b>–<b>c</b>) Undulations in snakes [<a href="#B22-micromachines-13-01783" class="html-bibr">22</a>]: the black-shaded areas are the muscle timing relative to bending in (<b>a</b>) swimming and (<b>b</b>) lateral undulation of a water snake and (<b>c</b>) sidewinding in a rattlesnake. The outside gray areas are past regions of static contact with the ground; note the onset and offset bending points. (<b>d</b>) Bends in our snake-inspired system: the transparent sections are the hyperelastic (soft) material connecting the ribs and providing antagonistic variable stiffness and energy storage–release. Kevlar fibers in the soft material and centerline provide actuation and prevent socket shifting, respectively.</p> Full article ">Figure 3
<p>(<b>a</b>) Force–displacement response for linear (top) and nonlinear (bottom) conical springs, where F is the applied force, and <math display="inline"><semantics> <mrow> <mo>Δ</mo> <mi>x</mi> </mrow> </semantics></math> is the displacement; (<b>b</b>) examples of geometric nonlinearity in slack–tension (top) and bending (bottom) structural members; and (<b>c</b>) stress–strain in materials exhibiting elastoplasticity (top) and nonlinear elasticity (bottom).</p> Full article ">Figure 4
<p>(<b>a</b>) Force–displacement curve of typical nonlinear hybrid compliance with linear softening (starts at <math display="inline"><semantics> <msub> <mi>x</mi> <mi>s</mi> </msub> </semantics></math>) and hardening (starts at <math display="inline"><semantics> <msub> <mi>x</mi> <mi>g</mi> </msub> </semantics></math>) stiffness regions; (<b>b</b>) note the linear and nonlinear displacements, <math display="inline"><semantics> <msub> <mi>x</mi> <mi>l</mi> </msub> </semantics></math> and <math display="inline"><semantics> <msub> <mi>x</mi> <mi>n</mi> </msub> </semantics></math>, respectively, for the same force. Thus, energy storage, the area under the curve, is higher in nonlinear (purple) than in linear (gray) hybrid compliance.</p> Full article ">Figure 5
<p>The musculoskeletal system consisted of six rigid segments: (<b>a</b>) front and (<b>b</b>) side views show the overall dimensions; and (<b>c</b>) shows the dimensions of a rigid segment, which consisted of four ribs. The fibers ran through holes in each segment to transmit the forces in hyperelastic material for actuation. The disk–socket joint enables rotation for undulation. The socket is the bottom cavity in the (<b>c</b>) isometric view.</p> Full article ">Figure 6
<p>Using imaging analysis, displacements were obtained experimentally for each rigid segment at the center and at the rib endpoints (highlighted in markers). Right (+X) and left (−X) are shown in red and blue, respectively.</p> Full article ">Figure 7
<p>The angles <math display="inline"><semantics> <msub> <mi>θ</mi> <mi>n</mi> </msub> </semantics></math> are the degrees of freedom of the musculoskeletal system with respect to the horizontal axis. The bottom rigid segment is fixed. The angle <math display="inline"><semantics> <msub> <mi>ϕ</mi> <mi>n</mi> </msub> </semantics></math> is the displacement between segments <span class="html-italic">n</span> and <math display="inline"><semantics> <mrow> <mi>n</mi> <mo>−</mo> <mn>1</mn> </mrow> </semantics></math>.</p> Full article ">Figure 8
<p>Local geometric parameters used to develop the kinematics.</p> Full article ">Figure 9
<p>Loading configurations in the (<b>a</b>) vertical and (<b>b</b>) horizontal directions. F is the applied load. The orange dash lines indicate the internal fibers.</p> Full article ">Figure 10
<p>The musculoskeletal system and the video camera were secured to a rigid test frame to maintain accurate measurements. A scale reference was positioned behind the system to facilitate reference for the tracking software.</p> Full article ">Figure 11
<p>Image tracking of musculoskeletal system motion was obtained using an app called Tracking. The ruler on the left side was utilized for scaling the experimental images.</p> Full article ">Figure 12
<p>Neo-Hookean hyperelastic constitutive model shows good agreement with the experimental stress–strain response of the soft material. The inset plot shows the nonlinear response at low strains, which is the softening (black curve) region in <a href="#micromachines-13-01783-f004" class="html-fig">Figure 4</a>. The straight red line highlights the nonlinear response.</p> Full article ">Figure 13
<p>The soft material model was expressed as linear and nonlinear springs (<math display="inline"><semantics> <msub> <mi>S</mi> <mi>n</mi> </msub> </semantics></math>) using constant and tunable resistive elements, respectively.</p> Full article ">Figure 14
<p>Force–response results for vertical loading obtained by applying force at the end of the left-side fibers. Experimental and analytical (from (<a href="#FD9-micromachines-13-01783" class="html-disp-formula">9</a>)) results are shown in markers and lines, respectively. Note the nonlinear bending behavior due to contraction of the soft material on one side and stretch on the other.</p> Full article ">Figure 15
<p>Force–response curves for horizontal loading obtained by applying force at the end of the top rigid segment. Experimental and analytical (from (<a href="#FD9-micromachines-13-01783" class="html-disp-formula">9</a>)) results are shown in markers and lines, respectively. Note the nonlinear bending behavior due to contraction of the soft material on one side and stretch on the other.</p> Full article ">Figure 16
<p>Contours of the displacement in the <span class="html-italic">X</span>-direction (<b>a</b>) and of the principle strain, <math display="inline"><semantics> <msub> <mi>ε</mi> <mrow> <mi>x</mi> <mi>x</mi> </mrow> </msub> </semantics></math>, due to a 29.4 N force applied to the end of the top rigid segment; (<b>a</b>) the maximum displacement (in mm) is <math display="inline"><semantics> <mrow> <mi>ϕ</mi> <mo>=</mo> <msup> <mrow> <mn>11.0</mn> </mrow> <mo>°</mo> </msup> </mrow> </semantics></math>, which is 4.4% less than the maximum experimental angle of 11.5°; (<b>b</b>) the strain is highest in the hyperelastic materials between the rigid segments (ribs), where energy is stored.</p> Full article ">Figure 17
<p>Total elastic energy storage for the musculoskeletal system in the bending load configuration. The energy released was the energy stored minus the energy dissipated. Experimental and analytical (from (<a href="#FD11-micromachines-13-01783" class="html-disp-formula">11</a>)) results are shown in markers and lines, respectively.</p> Full article ">Figure 18
<p>Undulation frequency for single- and double-sided tension configurations in blue and orange, respectively. The frequency appears to plateau asymptotically as the internal force is increased for both systems.</p> Full article ">Figure 19
<p>Damped undulation due to energy dissipation for single- and double-sided tension configurations in blue and orange, respectively. The damping ratio appears to increase linearly as the internal force is increased for both systems.</p> Full article ">
10 pages, 21721 KiB  
Article
Millimeter-Wave Permittivity Variations of an HR Silicon Substrate from the Photoconductive Effect
by Charlotte Tripon-Canseliet and Jean Chazelas
Micromachines 2022, 13(10), 1782; https://doi.org/10.3390/mi13101782 - 19 Oct 2022
Cited by 1 | Viewed by 1516
Abstract
The photoinduced microwave complex permittivity of a highly resistive single-crystal silicon wafer was extracted from a bistatic free-space characterization test bench operating in the 26.5–40 GHz frequency band under CW optical illumination at wavelengths of 806 and 971 nm. Significant variations in the [...] Read more.
The photoinduced microwave complex permittivity of a highly resistive single-crystal silicon wafer was extracted from a bistatic free-space characterization test bench operating in the 26.5–40 GHz frequency band under CW optical illumination at wavelengths of 806 and 971 nm. Significant variations in the real and imaginary parts of the substrate’s permittivity induced by direct photoconductivity are reported, with an optical power density dependence, in agreement with the theoretical predictions. These experimental results open the route to ultrafast system reconfiguration of microwave devices in integrated technology by an external EMI-protected and contactless control with unprecedented performance. Full article
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<p>Calibration technique schematic for bistatic measurements in free space.</p> Full article ">Figure 2
<p>Schematic view (<b>a</b>) and image (<b>b</b>) of the dedicated free-space microwave bistatic characterization technique developed at PSL/ESPCI.</p> Full article ">Figure 3
<p>Microwave silicon permittivity under dark conditions—Experimental and simulation data in real (<b>a</b>) and imaginary (<b>b</b>) parts.</p> Full article ">Figure 4
<p>Microwave silicon permittivity variations. Experimental (solid) and simulation (dashed) data comparison under optical illumination in real and imaginary parts: <math display="inline"><semantics> <msub> <mi>λ</mi> <mrow> <mi>o</mi> <mi>p</mi> <mi>t</mi> </mrow> </msub> </semantics></math> = 806 nm.</p> Full article ">Figure 5
<p>Microwave silicon permittivity variations. Experimental (solid) and simulation (dashed) comparison under optical illumination in real and imaginary parts: <math display="inline"><semantics> <msub> <mi>λ</mi> <mrow> <mi>o</mi> <mi>p</mi> <mi>t</mi> </mrow> </msub> </semantics></math> = 971 nm.</p> Full article ">Figure 6
<p>Extracted photoconductivity parameter variation with microwave frequency under optical illumination of OPD = 0.24 W/cm<sup>2</sup> and optical wavelengths of 971 nm (<b>left</b>) and 806 nm (<b>right</b>).</p> Full article ">
16 pages, 8369 KiB  
Article
Effect of Tool Coatings on Machining Properties of Compacted Graphite Iron
by Xiaonan Ai, Jun Tan, Hui Sun, Lu Lu, Zhenming Yang, Zhongguang Yu, Guojun Liao, Shiyong Li, Yilin Jin, Yusheng Niu, Ning He and Xiuqing Hao
Micromachines 2022, 13(10), 1781; https://doi.org/10.3390/mi13101781 - 19 Oct 2022
Cited by 4 | Viewed by 1548
Abstract
Compacted graphite iron (CGI) has become the most ideal material for automotive engine manufacturing owing to its excellent mechanical properties. However, tools are severely worn during processing, considerably shortening their lifespan. In this study, we prepared a series of cemented carbide-coated tools and [...] Read more.
Compacted graphite iron (CGI) has become the most ideal material for automotive engine manufacturing owing to its excellent mechanical properties. However, tools are severely worn during processing, considerably shortening their lifespan. In this study, we prepared a series of cemented carbide-coated tools and evaluated their coating properties in cutting tests. Among all tested coatings, PVD coating made of AlCrN (AC) presented with the best surface integrity and mechanical properties, achieving the best comprehensive performance in the coating test. The AC-coated tool also exhibited the best cutting performance at a low speed of 120 m/min, corresponding to a 60% longer cutting life and the lowest workpiece surface roughness relative to other coated tools. In the cutting test at a high speed of 350 m/min, the CVD double-layer coated tool (MT) with a TiCN inner layer of and an Al2O3 outer layer had a 70% longer cutting life and the lowest workpiece surface roughness relative to other coated tools. Full article
(This article belongs to the Special Issue Advanced Manufacturing Technology and Systems, 2nd Edition)
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<p>Cutting tool inserts with different coatings.</p> Full article ">Figure 2
<p>Scratch test: (<b>a</b>) schematic diagram; (<b>b</b>) schematic diagram of the judgment criteria for binding force.</p> Full article ">Figure 3
<p>Crystal phase diagram of CGI.</p> Full article ">Figure 4
<p>Images of the morphology of the coating surfaces.</p> Full article ">Figure 5
<p>Rake face images of MT- and AC-coated cutting tools.</p> Full article ">Figure 6
<p>Thickness and composition of MT and AC coatings.</p> Full article ">Figure 7
<p>Profile during nanoindentation test.</p> Full article ">Figure 8
<p>Loading–unloading curve of the nanoindentation test.</p> Full article ">Figure 9
<p>Hardness and elastic modulus of different coatings.</p> Full article ">Figure 10
<p>H/E* and H<sup>3</sup>/E*<sup>2</sup> values of different coatings.</p> Full article ">Figure 11
<p>Scratch morphology of each coating surface.</p> Full article ">Figure 12
<p>Binding force and membrane breaking force of each coating.</p> Full article ">Figure 13
<p>Surface roughness of the workpiece of different coatings at low speed.</p> Full article ">Figure 14
<p>Tool flank face wear of different coatings at low speed.</p> Full article ">Figure 15
<p>Tool flank wear of different coatings after cutting 1700 m at low speed.</p> Full article ">Figure 16
<p>Surface roughness of the workpiece with different coatings at high speed.</p> Full article ">Figure 17
<p>Tool flank wear of different coatings at high speed.</p> Full article ">Figure 18
<p>Tool flank wear of different coatings after cutting 1000 m at high speed.</p> Full article ">
18 pages, 2100 KiB  
Review
Applications of Nano/Micromotors for Treatment and Diagnosis in Biological Lumens
by Shandeng Huang, Yinghua Gao, Yu Lv, Yun Wang, Yinghao Cao, Weisong Zhao, Dongqing Zuo, Haoran Mu and Yingqi Hua
Micromachines 2022, 13(10), 1780; https://doi.org/10.3390/mi13101780 - 19 Oct 2022
Cited by 4 | Viewed by 2741
Abstract
Natural biological lumens in the human body, such as blood vessels and the gastrointestinal tract, are important to the delivery of materials. Depending on the anatomic features of these biological lumens, the invention of nano/micromotors could automatically locomote targeted sites for disease treatment [...] Read more.
Natural biological lumens in the human body, such as blood vessels and the gastrointestinal tract, are important to the delivery of materials. Depending on the anatomic features of these biological lumens, the invention of nano/micromotors could automatically locomote targeted sites for disease treatment and diagnosis. These nano/micromotors are designed to utilize chemical, physical, or even hybrid power in self-propulsion or propulsion by external forces. In this review, the research progress of nano/micromotors is summarized with regard to treatment and diagnosis in different biological lumens. Challenges to the development of nano/micromotors more suitable for specific biological lumens are discussed, and the overlooked biological lumens are indicated for further studies. Full article
(This article belongs to the Special Issue Medical Micro/Nanorobots)
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<p>Nano/micromotors in the gastrointestinal tract. (<b>a</b>) The multi-chamber biconical tubular micromotor is divided into two parts. The first part was the propulsion element based on zinc; the second part is the drug delivery element. When the motor penetrated the mucosal layer, the pH-responsive cap dissolved and released the drugs. Reprinted with permission from ref. [<a href="#B33-micromachines-13-01780" class="html-bibr">33</a>]. (<b>b</b>) The magnesium (Mg)-based multi-layer spherical-like Janus nano/micromotor uses stomach acid as fuel to actuate. Reprinted with permission from ref. [<a href="#B34-micromachines-13-01780" class="html-bibr">34</a>]. (<b>c</b>) The magnesium-based hydrogel nano/micromotor is inspired by the sucking disc of an octopus. Mg reacts with hydrogen ions to form hydrogen to drive the nano/micromotor. Reprinted with permission from ref. [<a href="#B37-micromachines-13-01780" class="html-bibr">37</a>].</p> Full article ">Figure 2
<p>Nano/micromotors in the urinary tract. (<b>a</b>) The speed and direction of the urea-driven Janus hollow mesoporous silica particle (JHP) nano/micromotor could be regulated. Reprinted with permission from ref. [<a href="#B54-micromachines-13-01780" class="html-bibr">54</a>]. Copyright© 2022, American Chemical Society. (<b>b</b>) The endogenous enzyme-driven Janus platelet nano/micromotor (JPL-motor) turned the urea into NH3 and CO<sub>2</sub>, delivering the DOX efficiently. Reprinted with permission from ref. [<a href="#B57-micromachines-13-01780" class="html-bibr">57</a>]. (<b>c</b>) The enzyme-photocatalyst tandem nano/micromotor could be propelled at a speed of 3.3 ± 0.3 μm/s in 50 mM urea and produced ROS to remove the bacterial biofilms. Reprinted with permission from ref. [<a href="#B60-micromachines-13-01780" class="html-bibr">60</a>]. (<b>d</b>) The velocity of photothermal interference (PTI) urease-modified PDA nano/micromotor (PDA@HSA@Ur) driven by enzyme catalysis could be enhanced when exposed to NIR laser light. Reprinted with permission from ref. [<a href="#B61-micromachines-13-01780" class="html-bibr">61</a>].</p> Full article ">Figure 3
<p>Nano/micromotors in the blood vessels. (<b>a</b>) Fe<sub>3</sub>O<sub>4</sub> nanoparticle-loaded RBC motors could be propelled by ultrasound fields. Reprinted with permission from ref. [<a href="#B69-micromachines-13-01780" class="html-bibr">69</a>]. Copyright © 2022, American Chemical Society. (<b>b</b>) Superparamagnetic motors coated with thrombin could agglutinate in a certain magnetic field and block the vessel. Reprinted with permission from ref. [<a href="#B76-micromachines-13-01780" class="html-bibr">76</a>]. (<b>c</b>) The LA of NO-driven silica motors with bowl-shaped mesoporous could react with ROS to produce NO to propel the motor. Reprinted with permission from ref. [<a href="#B78-micromachines-13-01780" class="html-bibr">78</a>,<a href="#B85-micromachines-13-01780" class="html-bibr">85</a>]. (<b>d</b>) The ejection of O<sub>2</sub> bubbles and the cavitation effect produced by the ultrasonication of O<sub>2</sub> could be the power source of the Janus rod (JR)-shaped motors. Reprinted with permission from ref. [<a href="#B82-micromachines-13-01780" class="html-bibr">82</a>,<a href="#B92-micromachines-13-01780" class="html-bibr">92</a>].</p> Full article ">Figure 4
<p>Nano/micromotors in other lumens. The motors composed of sperm can even fight against continuous or pulsating blood flow. Reprinted with permission from ref. [<a href="#B107-micromachines-13-01780" class="html-bibr">107</a>]. Copyright © 2022 American Chemical Society.</p> Full article ">
10 pages, 1773 KiB  
Article
A Hydrogel-Based Self-Sensing Underwater Actuator
by Shuyu Wang, Zhaojia Sun, Shuaiyang Duan, Yuliang Zhao, Xiaopeng Sha, Shifeng Yu and Lei Zuo
Micromachines 2022, 13(10), 1779; https://doi.org/10.3390/mi13101779 - 19 Oct 2022
Cited by 1 | Viewed by 2357
Abstract
Soft robots made of hydrogels are suited for underwater exploration due to their biocompatibility and compliancy. Yet, reaching high dexterity and actuation force for hydrogel-based actuators is challenging. Meanwhile, real-time proprioception is critical for feedback control. Moreover, sensor integration to mimic living organisms [...] Read more.
Soft robots made of hydrogels are suited for underwater exploration due to their biocompatibility and compliancy. Yet, reaching high dexterity and actuation force for hydrogel-based actuators is challenging. Meanwhile, real-time proprioception is critical for feedback control. Moreover, sensor integration to mimic living organisms remains problematic. To address these challenges, we introduce a hydrogel actuator driven by hydraulic force with a fast response (time constant 0.83 s). The highly stretchable and conductive hydrogel (1400% strain) is molded into the PneuNet shape, and two of them are further assembled symmetrically to actuate bi-directionally. Then, we demonstrate its bionic application for underwater swimming, showing 2 cm/s (0.19 BL/s) speed. Inspired by biological neuromuscular systems’ sensory motion, which unifies the sensing and actuation in a single unit, we explore the hydrogel actuator’s self-sensing capacity utilizing strain-induced resistance change. The results show that the soft actuator’s proprioception can monitor the undulation in real-time with a sensitivity of 0.2%/degree. Furthermore, we take a finite-element method and first-order differential equations to model the actuator’s bending in response to pressure. We show that such a model can precisely predict the robot’s bending response over a range of pressures. With the self-sensing actuator and the proposed model, we expect the new approach can lead to future soft robots for underwater exploration with feedback control, and the underlying mechanism of the undulation control might offer significant insights for biomimetic research. Full article
(This article belongs to the Special Issue Micro- and Nano-Systems for Manipulation, Actuation and Sensing)
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<p>The fabrication process of the bi-directional bending actuator. (<b>A</b>,<b>B</b>) The process of preparing precursor liquid. (<b>C</b>,<b>D</b>) We pour the precursor into the prepared mold at night for cross-linking curing under UV light. (<b>E</b>,<b>F</b>) We get two symmetric chambers and an intermediate layer after mold release. We glue them with binder and assemble them into a bidirectional bending actuator.</p> Full article ">Figure 2
<p>(<b>a</b>) The schematic diagram of the experimental setup. (<b>b</b>) The stress–strain curve of the hydrogel. (<b>c</b>) The generated force of the actuator at different pressures.</p> Full article ">Figure 3
<p>(<b>a</b>) The bending effect of the actuator at different angles in experiments and simulations. (<b>b</b>) Simulated effects of the actuator bending bidirectionally. (<b>c</b>) The bending angles of the actuator under different pressures in experiments and simulations.</p> Full article ">Figure 4
<p>Images of the actuator moving in water in a time sequence of i–iv.</p> Full article ">Figure 5
<p>(<b>a</b>) The relationships between ΔR/R and angles. (<b>b</b>) The actuator’s self-sensing angle versus the camera’s recorded angle. The asterisks represent the actuator’s self-sensing angles and the camera’s recorded angles under different pressure. The sensor’s error is also provided by subtracting the measured difference and is indicated by the solid red line. The dotted line represents angular consistency under ideal conditions. (<b>c</b>) The curves show the change of resistance and angles of the actuator during cycles of bending and recovery. (<b>d</b>) Fitted parameters versus pressures. (<b>e</b>) Comparison of the model’s prediction and the step responses of the soft actuator subjected to different input pressures. The dotted lines represent the model’s prediction. The solid lines indicate the experimental data.</p> Full article ">
20 pages, 1506 KiB  
Article
Activation and Switching of Supramolecular Chemical Signals in Multi-Output Microfluidic Devices
by Artem Bezrukov and Yury Galyametdinov
Micromachines 2022, 13(10), 1778; https://doi.org/10.3390/mi13101778 - 19 Oct 2022
Cited by 4 | Viewed by 1960
Abstract
In this study, we report on the developing of a continuous microfluidic reaction device that allows selective activation of polyelectrolyte-surfactant chemical signals in microflows and switches them between multiple outputs. A numerical model was developed for convection-diffusion reaction processes in reactive polymer-colloid microfluidic [...] Read more.
In this study, we report on the developing of a continuous microfluidic reaction device that allows selective activation of polyelectrolyte-surfactant chemical signals in microflows and switches them between multiple outputs. A numerical model was developed for convection-diffusion reaction processes in reactive polymer-colloid microfluidic flows. Matlab scripts and scaling laws were developed for this model to predict reaction initiation and completion conditions in microfluidic devices and the location of the reaction front. The model allows the optimization of microfluidic device geometry and the setting of operation modes that provide release of the reaction product through specific outputs. Representing a chemical signal, polyelectrolyte-surfactant reaction products create various logic gate states at microfluidic chip outputs. Such systems may have potential as biochemical signal transmitters in organ-on-chip applications or chemical logic gates in cascaded microfluidic devices. Full article
(This article belongs to the Special Issue Micro- and Nano-Systems for Manipulation, Actuation and Sensing)
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<p>(<b>a</b>) Schematic diagram of feeding the reacting solutions and the solvent into a microfluidic chip and separating the reaction mixture into 3 streams; (<b>b</b>) The 3-input and 3-output microfluidic chips with width = 200 µm and length = 15 mm, the microchannels were filled with dye (phenolphthalein in 0.1 M KOH) to aid visualization; (<b>c</b>) SDS binding by PDADMAC macroions; (<b>d</b>) Chemical signal detection by DLS: initial 10–15 nm polymers macromolecules or smaller particles and 100–150 nm aggregates of complexes. The SDS:PDADMAC molar ratio in the test reaction was 0.2:1.</p> Full article ">Figure 2
<p>Geometry of microfluidic devices. The reagents were fed through the side input channels, the solvent was fed through the central input channel to avoid an immediate mixing of reagents and the start of reaction. The product formed at a distance from the junction of the input channels and then was distributed between output channels, depending on the reaction front position.</p> Full article ">Figure 3
<p>Numerical simulations results at the main channel end (x = L) for the PDADMAC-SDS complexation reaction. Concentration curves: blue—PDADMAC, red—SDS, yellow—complex. Flow rates: (<b>a</b>) A, B—5 μL/min, solvent—10 μL/min; (<b>b</b>) A, B—5 μL/min, solvent—3 μL/min; (<b>c</b>) A, B—0.2 μL/min, solvent—1.2 μL/min; (<b>d</b>) A, B—10 μL/min, solvent—2 μL/min; (<b>e</b>) A, B, solvent—1 μL/min; (<b>f</b>) A, B, solvent—0.1 μL/min. The main channel width = 300 µm and length = 15 mm.</p> Full article ">Figure 4
<p>Visualization of chemical signals near microchip outputs (x = L) in the microfluidic experiments with the PDADMAC-SDS reaction pair: “1”—the product is present in an output (precipitate), “0”—no product in an output (no precipitate). The flow rates of the reagents and the solvent were identical to those of the numerical simulations shown in <a href="#micromachines-13-01778-f003" class="html-fig">Figure 3</a>: (<b>a</b>) A, B—5 μL/min, solvent—10 μL/min; (<b>b</b>) A, B—5 μL/min, solvent—3 μL/min; (<b>c</b>) A, B—0.2 μL/min, solvent—1.2 μL/min; (<b>d</b>) A, B—10 μL/min, solvent—2 μL/min; (<b>e</b>) A, B, solvent—1 μL/min; (<b>f</b>) A, B, solvent—0.1 μL/min. The main channel width = 300 µm and length = 15 mm.</p> Full article ">
24 pages, 19663 KiB  
Article
A Multi-Part Orientation Planning Schema for Fabrication of Non-Related Components Using Additive Manufacturing
by Osama Abdulhameed, Syed Hammad Mian, Khaja Moiduddin, Abdulrahman Al-Ahmari, Naveed Ahmed and Mohamed K. Aboudaif
Micromachines 2022, 13(10), 1777; https://doi.org/10.3390/mi13101777 - 19 Oct 2022
Cited by 2 | Viewed by 2256
Abstract
Additive manufacturing (AM) is a technique that progressively deposits material in layer-by-layer manner (or in additive fashion) for producing a three-dimensional (3D) object, starting from the computer-aided design (CAD) model. This approach allows for the printing of complicated shaped objects and is quickly [...] Read more.
Additive manufacturing (AM) is a technique that progressively deposits material in layer-by-layer manner (or in additive fashion) for producing a three-dimensional (3D) object, starting from the computer-aided design (CAD) model. This approach allows for the printing of complicated shaped objects and is quickly gaining traction in the aerospace, medical implant, jewelry, footwear, automotive, and fashion industries. AM, which was formerly used for single part customization, is currently being considered for mass customization of parts because of its positive impacts. However, part quality and build time are two main impediments to the deployment of AM for mass production. The optimal part orientation is fundamental for maximizing the part’s quality as well as being critical for reducing the fabrication time. This research provides a new method for multi-part AM production that improves quality while reducing overall build time. The automatic setup planning or orientation approach described in this paper employs two objective functions: the quality of the build component and the build time. To tackle the given problem, it introduces a three-step genetic algorithm (GA)-based solution. A feature-based technique is utilized to generate a collection of finite alternative orientations for each component within a specific part group to ensure each part’s individual build quality. Then, a GA was utilized to find the best combination of part build orientations at a global optimal level to reduce material consumption and build time. A case study of orienting nine components concurrently inside a given building chamber was provided for illustration. The findings suggest that the developed technique can increase quality, reduce support waste, and shorten overall production time. When components are positioned optimally rather than in random orientations, build time and support volume are reduced by approximately 7% and 16%, respectively. Full article
(This article belongs to the Special Issue Recent Advances in 3D Printing and Additive Manufacturing)
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<p>Methodology adopted to optimize orientation for multi-part production.</p> Full article ">Figure 2
<p>Designation of component’s faces.</p> Full article ">Figure 3
<p>Operation of (<b>a</b>) single-point crossover; (<b>b</b>) two-point crossover.</p> Full article ">Figure 4
<p>Working of double-inversion mutation operator [<a href="#B89-micromachines-13-01777" class="html-bibr">89</a>].</p> Full article ">Figure 5
<p>Case Studies (<b>a</b>) Component 1; (<b>b</b>) Component 2; (<b>c</b>) Component 3; (<b>d</b>) Component 4; (e) Component 5; (<b>f</b>) Component 6; (<b>g</b>) Component 7; (<b>h</b>) Component 8; (<b>i</b>) Component 9.</p> Full article ">Figure 6
<p>Components and their dimensions.</p> Full article ">Figure 7
<p>Components in two different random orientations on the build platform.</p> Full article ">Figure 8
<p>(<b>a</b>) Dimension Elite 3D printer (Courtesy: STRATASYS); (<b>b</b>) Component arrangement.</p> Full article ">Figure 9
<p>(<b>a</b>) Change in fitness value; (<b>b</b>) Variation in CPU time.</p> Full article ">Figure 10
<p>Fabricated components manufactured using FDM. (<b>a</b>) With supports; (<b>b</b>) After removing supports.</p> Full article ">Figure 11
<p>Comparison of optimum and random orientations (<b>a</b>) Support Material; (<b>b</b>) Build Time.</p> Full article ">Figure 12
<p>Set up to capture the shape of test specimens.</p> Full article ">Figure 13
<p>Deviation between the 3D printed parts and their CAD models from the 3D comparison—(<b>a</b>) Component 1; (<b>b</b>) Component 2; (<b>c</b>) Component 3; (<b>d</b>) Component 4; (<b>e</b>) Component 5; (<b>f</b>) Component 6; (<b>g</b>) Component 7; (<b>h</b>) Component 8; (<b>i</b>) Component 9.</p> Full article ">Figure 13 Cont.
<p>Deviation between the 3D printed parts and their CAD models from the 3D comparison—(<b>a</b>) Component 1; (<b>b</b>) Component 2; (<b>c</b>) Component 3; (<b>d</b>) Component 4; (<b>e</b>) Component 5; (<b>f</b>) Component 6; (<b>g</b>) Component 7; (<b>h</b>) Component 8; (<b>i</b>) Component 9.</p> Full article ">Figure 13 Cont.
<p>Deviation between the 3D printed parts and their CAD models from the 3D comparison—(<b>a</b>) Component 1; (<b>b</b>) Component 2; (<b>c</b>) Component 3; (<b>d</b>) Component 4; (<b>e</b>) Component 5; (<b>f</b>) Component 6; (<b>g</b>) Component 7; (<b>h</b>) Component 8; (<b>i</b>) Component 9.</p> Full article ">
21 pages, 5145 KiB  
Article
Design of Improved Flow-Focusing Microchannel with Constricted Continuous Phase Inlet and Study of Fluid Flow Characteristics
by Zhaohui Wang, Weibing Ding, Yiwei Fan, Jian Wang, Jie Chen and Hongxia Wang
Micromachines 2022, 13(10), 1776; https://doi.org/10.3390/mi13101776 - 19 Oct 2022
Cited by 6 | Viewed by 1772
Abstract
This paper proposed an improved flow-focusing microchannel with a constricted continuous phase inlet to increase microbubble generation frequency and reduce microbubbles’ diameter. The design variables were obtained by Latin hypercube sampling, and the radial basis function (RBF) surrogate model was used to establish [...] Read more.
This paper proposed an improved flow-focusing microchannel with a constricted continuous phase inlet to increase microbubble generation frequency and reduce microbubbles’ diameter. The design variables were obtained by Latin hypercube sampling, and the radial basis function (RBF) surrogate model was used to establish the relationship between the objective function (microbubble diameter and generation frequency) and the design variables. Moreover, the optimized design of the nondominated sorting genetic algorithm II (NSGA-II) algorithm was carried out. Finally, the optimization results were verified by numerical simulations and compared with those of traditional microchannels. The results showed that dripping and squeezing regimes existed in the two microchannels. The constricted continuous phase inlet enhanced the flow-focusing effect of the improved microchannel. The diameter of microbubbles obtained from the improved microchannel was reduced from 2.8141 to 1.6949 μm, and the generation frequency was increased from 64.077 to 175.438 kHz at the same capillary numbers (Ca) compared with the traditional microchannel. According to the fitted linear function, it is known that the slope of decreasing microbubble diameter with increasing Ca number and the slope of increasing generation frequency with increasing Ca number are greater in the improved microchannel compared with those in the traditional microchannel. Full article
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<p>Schematics for improved flow-focusing microchannel.</p> Full article ">Figure 2
<p>Grid independence test.</p> Full article ">Figure 3
<p>Comparison of numerical results of dimensionless microbubble size with experimental results.</p> Full article ">Figure 4
<p>RBF neural network topology.</p> Full article ">Figure 5
<p>Multi-objective optimization flow chart.</p> Full article ">Figure 6
<p>Comparison between prediction and reality: (<b>a</b>) D and (<b>b</b>) F.</p> Full article ">Figure 7
<p>Sensitivity analysis.</p> Full article ">Figure 8
<p>Pareto optimal front.</p> Full article ">Figure 9
<p>Time evolution of hydrodynamic information during microbubble generation in improved microchannel (Ca = 0.0139, U<sub>d</sub> = 0.2 m/s): (<b>a</b>) evolution of the interface, (<b>b</b>) evolution of pressure field, and (<b>c</b>) evolution of velocity field.</p> Full article ">Figure 10
<p>Time evolution of hydrodynamic information during microbubble generation in traditional microchannel (Ca = 0.0139, U<sub>d</sub> = 0.2 m/s): (<b>a</b>) evolution of the interface, (<b>b</b>) evolution of pressure field, and (<b>c</b>) evolution of velocity field.</p> Full article ">Figure 11
<p>Variation of tip length with time during formation of microbubbles in two microchannels.</p> Full article ">Figure 12
<p>Pressure curve: (<b>a</b>) improved microchannel; (<b>b</b>) traditional microchannel (Ca = 0.0139, U<sub>d</sub> = 0.2 m/s).</p> Full article ">Figure 13
<p>Variation of pressure at p-point with time in traditional and improved microchannels.</p> Full article ">Figure 14
<p>(<b>a</b>) Microbubble diameter (D) and (<b>b</b>) generation frequency (F) as a function of capillary number (Ca) (U<sub>d</sub> = 0.2 m/s).</p> Full article ">
8 pages, 1820 KiB  
Article
Zinc Carboxylate Surface Passivation for Enhanced Optical Properties of In(Zn)P Colloidal Quantum Dots
by Doheon Yoo, Eunyoung Bak, Hae Mee Ju, Yoo Min Shin and Min-Jae Choi
Micromachines 2022, 13(10), 1775; https://doi.org/10.3390/mi13101775 - 19 Oct 2022
Cited by 2 | Viewed by 2007
Abstract
Indium phosphide (InP) colloidal quantum dots (CQDs) have generated great interest as next-generation light-emitting materials owing to their narrow emission spectra and environment-friendly components. The minimized surface defects is essential to achieve narrow full-width at half-maximum (FWHM) and high photoluminescence quantum yield (PLQY). [...] Read more.
Indium phosphide (InP) colloidal quantum dots (CQDs) have generated great interest as next-generation light-emitting materials owing to their narrow emission spectra and environment-friendly components. The minimized surface defects is essential to achieve narrow full-width at half-maximum (FWHM) and high photoluminescence quantum yield (PLQY). However, InP CQDs are readily oxidized in ambient condition, which results in formation of oxidation defect states on the surface of InP CQDs. Herein, we introduce a strategy to successfully passivate the surface defects of InP core by zinc complexes. The zinc carboxylates passivation reduces FWHM of InP CQDs from 130 nm to 70 nm and increases PLQY from 1% to 14% without shelling. Furthermore, the photoluminescence (PL) peak has shifted from 670 nm to 510 nm with an increase of zinc carboxylates passivation, which suggests that excessive zinc carboxylates functions as a size-regulating reagent in the synthesis. Full article
(This article belongs to the Special Issue Quantum Dot Frontiers)
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<p>(<b>a</b>–<b>d</b>) absorption spectroscopy and PL measurement of In(Zn)P core (<b>a</b>,<b>b</b>) and In(Zn)P @ ZnS CQDs (<b>c</b>,<b>d</b>). Samples under UV illumination of In(Zn)P core (left to right, Zn 0, Zn 0.4, Zn 0.8, Zn1.2) (<b>e</b>) and In(Zn)P @ ZnS CQDs (left to right, Zn 0 @ ZnS, Zn 0.4 @ ZnS, Zn 0.8 @ ZnS, Zn 1.2 @ ZnS) (<b>f</b>). (<b>g</b>,<b>h</b>) PLQY (<b>g</b>) and FWHM (<b>h</b>) of CQDs depending on Zn loading amounts in the synthesis.</p> Full article ">Figure 2
<p>TEM images of synthesized In(Zn)P @ ZnS QDs and particle size distribution. (<b>a</b>,<b>b</b>) InP @ ZnS (Zn 0); (<b>c</b>,<b>d</b>) In(Zn)P @ ZnS (Zn 1.2).</p> Full article ">Figure 3
<p>(<b>a</b>–<b>d</b>) XPS analysis of synthesized samples depending on the Zn loading amounts. (<b>e</b>) Quantitative analysis result of the synthesized samples. (<b>f</b>) Offset XPS spectrum of Zn 2p.</p> Full article ">
11 pages, 4001 KiB  
Article
Fabrication and Characterization of an Optimized Low-Loss Two-Mode Fiber for Optoacoustic Sensing
by Zelin Zhang, Guanglei You, Yu Qin, Jianqin Peng, Shuhong Xie, Xinli Jiang, Caoyuan Wang, Ruowei Yu, Yichun Shen and Limin Xiao
Micromachines 2022, 13(10), 1774; https://doi.org/10.3390/mi13101774 - 19 Oct 2022
Viewed by 1671
Abstract
An optimized multi-step index (MSI) 2-LP-mode fiber is proposed and fabricated with low propagation loss of 0.179 dB/km, low intermodal crosstalk and excellent bend resistance. We experimentally clarified the characteristics of backward Brillouin scattering (BBS) and forward Brillouin scattering (FBS) induced by radial [...] Read more.
An optimized multi-step index (MSI) 2-LP-mode fiber is proposed and fabricated with low propagation loss of 0.179 dB/km, low intermodal crosstalk and excellent bend resistance. We experimentally clarified the characteristics of backward Brillouin scattering (BBS) and forward Brillouin scattering (FBS) induced by radial acoustic modes (R0,m) in the fabricated MSI 2-LP-mode fiber, respectively. Via the use of this two-mode fiber, we demonstrated a novel discriminative measurement method of temperature and acoustic impedance based on BBS and FBS, achieving improved experimental measurement uncertainties of 0.2 °C and 0.019 kg/(s·mm2) for optoacoustic chemical sensing. The low propagation loss of the sensing fiber and the new measurement method based on both BBS and FBS may pave the way for long-distance and high spatial resolution distributed fiber sensors. Full article
(This article belongs to the Section E：Engineering and Technology)
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<p>Designed and measured refractive index profile of MSI 2-LP-mode fiber.</p> Full article ">Figure 2
<p>Calculated electric fields of guided LP mode LP<sub>01</sub> and LP<sub>11</sub> at 1550 nm in the optimized MSI 2-LP-mode fiber. (<b>a</b>) Two-dimensional mode profiles, and (<b>b</b>) electric field mode pattern.</p> Full article ">Figure 3
<p>(<b>a</b>) Two-dimensional (2D) mode profiles and (<b>b</b>) field patterns of four acoustic modes.</p> Full article ">Figure 4
<p>Numerical results of BGS of the MSI 2-LP-mode fiber.</p> Full article ">Figure 5
<p>(<b>a</b>) The density vibration profile and (<b>b</b>) spatial distribution of <span class="html-italic">R</span><sub>0,7</sub> mode.</p> Full article ">Figure 6
<p>The measured FBS spectrum (FBSS) in the MSI 2-LP-mode fiber.</p> Full article ">Figure 7
<p>Experimental setup for observing BGS and FBSS in the MSI 2-LP-mode fiber.</p> Full article ">Figure 8
<p>Frequency shift for (<b>a</b>) <span class="html-italic">R</span><sub>0,7</sub>-induced FBSS and (<b>b</b>) BGS as a function of temperature.</p> Full article ">Figure 9
<p>Frequency shift for (<b>a</b>) <span class="html-italic">R</span><sub>0,7</sub>-induced FBSS and (<b>b</b>) BGS as a function of acoustic impedance.</p> Full article ">Figure 10
<p>The measured induced FBSS induced by radial acoustic mode of (<b>a</b>) <span class="html-italic">R</span><sub>0,7</sub> at State 1 and (<b>c</b>) <span class="html-italic">R</span><sub>0,7</sub> at State 2 as well as BGS at (<b>b</b>) State 1 and (<b>d</b>) State 2.</p> Full article ">
18 pages, 6905 KiB  
Review
Advanced MXene-Based Micro- and Nanosystems for Targeted Drug Delivery in Cancer Therapy
by Fatemeh Mohajer, Ghodsi Mohammadi Ziarani, Alireza Badiei, Siavash Iravani and Rajender S. Varma
Micromachines 2022, 13(10), 1773; https://doi.org/10.3390/mi13101773 - 19 Oct 2022
Cited by 16 | Viewed by 4097
Abstract
MXenes with unique mechanical, optical, electronic, and thermal properties along with a specific large surface area for surface functionalization/modification, high electrical conductivity, magnetic properties, biocompatibility, and low toxicity have been explored as attractive candidates for the targeted delivery of drugs in cancer therapy. [...] Read more.
MXenes with unique mechanical, optical, electronic, and thermal properties along with a specific large surface area for surface functionalization/modification, high electrical conductivity, magnetic properties, biocompatibility, and low toxicity have been explored as attractive candidates for the targeted delivery of drugs in cancer therapy. These two-dimensional materials have garnered much attention in the field of cancer therapy since they have shown suitable photothermal effects, biocompatibility, and luminescence properties. However, outstanding challenging issues regarding their pharmacokinetics, biosafety, targeting properties, optimized functionalization, synthesis/reaction conditions, and clinical translational studies still need to be addressed. Herein, recent advances and upcoming challenges in the design of advanced targeted drug delivery micro- and nanosystems in cancer therapy using MXenes have been discussed to motivate researchers to further investigate this field of science. Full article
(This article belongs to the Special Issue Rise of MXenes: A New Family of Two-Dimensional (2D) Materials and Devices)
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<p>MXenes and their derivatives with versatile biomedical potentials.</p> Full article ">Figure 2
<p>Schematic diagram of MXene-based biomimetic plasmonic assembly for targeted cancer therapy [<a href="#B94-micromachines-13-01773" class="html-bibr">94</a>].</p> Full article ">Figure 3
<p>Synthesis of 2D-ultrathin MXene/DOXjade platforms for targeted cancer therapy [<a href="#B95-micromachines-13-01773" class="html-bibr">95</a>].</p> Full article ">Figure 4
<p>A plausible mechanism of 2D-ultrathin MXene/DOXjade platform for cancer therapy [<a href="#B95-micromachines-13-01773" class="html-bibr">95</a>].</p> Full article ">Figure 5
<p>(<b>A</b>) Schematic diagram of Ti<sub>3</sub>C<sub>2</sub> nanosheet-based camouflaged bionic cascaded-enzyme nanoreactor. (<b>B</b>) The possible mechanism of action for the designed MXene-based camouflaged bionic cascaded-enzyme nanoreactor (in vivo) [<a href="#B100-micromachines-13-01773" class="html-bibr">100</a>].</p> Full article ">Figure 6
<p>A schematic diagram of FNC inhibited inflammation and osteoclastogenesis. (<b>A</b>) Local injection of FNC at osteolytic sites. (<b>B</b>) Materials interaction between macrophages and osteoclasts influenced inflammation and osteoclastogenesis. (<b>C</b>) FNC was phagocytosed, and FNC exhibited the effect of ROS adsorption. Subsequently, the inflammatory and osteoclast-specific genes were down-regulated [<a href="#B101-micromachines-13-01773" class="html-bibr">101</a>].</p> Full article ">Figure 7
<p>(<b>A</b>) Pictorial representation for the working mechanism of CGDSTC nanosheets. (<b>B</b>) The preparative process of CGDSTC nanosheets [<a href="#B33-micromachines-13-01773" class="html-bibr">33</a>].</p> Full article ">Figure 8
<p>The preparative process of MXene quantum dot/ZIF-based systems for anticancer drug delivery [<a href="#B97-micromachines-13-01773" class="html-bibr">97</a>].</p> Full article ">Figure 9
<p>The preparation of few-layer Ti<sub>3</sub>C<sub>2</sub>Tx MXene nanosheets with high chemical stability using an IL-assisted exfoliating (red patterns) method for photoacoustic imaging-guided synergistic photothermal/chemotherapy of tumors [<a href="#B104-micromachines-13-01773" class="html-bibr">104</a>].</p> Full article ">Figure 10
<p>The preparative process and function of designed MXenes for cancer nanotherapy [<a href="#B106-micromachines-13-01773" class="html-bibr">106</a>].</p> Full article ">
7 pages, 2353 KiB  
Article
A Novel Capacitorless 1T DRAM with Embedded Oxide Layer
by Dongxue Zhao, Zhiliang Xia, Tao Yang, Yuancheng Yang, Wenxi Zhou and Zongliang Huo
Micromachines 2022, 13(10), 1772; https://doi.org/10.3390/mi13101772 - 19 Oct 2022
Viewed by 3344
Abstract
A novel vertical dual surrounding gate transistor with embedded oxide layer is proposed for capacitorless single transistor DRAM (1T DRAM). The embedded oxide layer is innovatively used to improve the retention time by reducing the recombination rate of stored holes and sensing electrons. [...] Read more.
A novel vertical dual surrounding gate transistor with embedded oxide layer is proposed for capacitorless single transistor DRAM (1T DRAM). The embedded oxide layer is innovatively used to improve the retention time by reducing the recombination rate of stored holes and sensing electrons. Based on TCAD simulations, the new structure is predicted to not only have the characteristics of fast access, random read and integration of 4F2 cell, but also to realize good retention and deep scaling. At the same time, the new structure has the potential of scaling compared with the conventional capacitorless 1T DRAM. Full article
(This article belongs to the Special Issue Advances in Emerging Nonvolatile Memory, Volume II)
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<p>The structure of the conventional DFM and the novel proposed structure of the capacitorless 1T DRAM with embedded oxide layer.</p> Full article ">Figure 2
<p>(<b>a</b>–<b>f</b>) The process flow of the1T DRAM with embedded oxide layer.</p> Full article ">Figure 3
<p>The simulation structure of the conventional DFM and the novel proposed structure.</p> Full article ">Figure 4
<p>The reading current of the conventional DFM after holding “1” state for different times at 85 °C.</p> Full article ">Figure 5
<p>The reading current of different regions of the conventional DFM after holding “1” state for different times at 85 °C.</p> Full article ">Figure 6
<p>The reading current of the proposed structure after holding “1” state for different times at 85 °C.</p> Full article ">Figure 7
<p>For holding “1” state, the number of stored holes in the body is compared after 64 ms at 85 °C when the diameter is reduced to 30 nm.</p> Full article ">
11 pages, 7215 KiB  
Article
Fabrication of Chiral 3D Microstructure Using Tightly Focused Multiramp Helico-Conical Optical Beams
by Jisen Wen, Qiuyuan Sun, Mengdi Luo, Chengpeng Ma, Zhenyao Yang, Chenyi Su, Chun Cao, Dazhao Zhu, Chenliang Ding, Liang Xu, Cuifang Kuang and Xu Liu
Micromachines 2022, 13(10), 1771; https://doi.org/10.3390/mi13101771 - 18 Oct 2022
Cited by 16 | Viewed by 2432
Abstract
Beams with optical vortices are widely used in various fields, including optical communication, optical manipulation and trapping, and, especially in recent years, in the processing of nanoscale structures. However, circular vortex beams are difficult to use for the processing of chiral micro and [...] Read more.
Beams with optical vortices are widely used in various fields, including optical communication, optical manipulation and trapping, and, especially in recent years, in the processing of nanoscale structures. However, circular vortex beams are difficult to use for the processing of chiral micro and nanostructures. This paper introduces a multiramp helical–conical beam that can produce a three-dimensional spiral light field in a tightly focused system. Using this spiral light beam and the two-photon direct writing technique, micro–nano structures with chiral characteristics in space can be directly written under a single exposure. The fabrication efficiency is more than 20 times higher than the conventional point-by-point writing strategy. The tightly focused properties of the light field were utilized to analyze the field-dependent properties of the micro–nano structure, such as the number of multiramp mixed screw-edge dislocations. Our results enrich the means of two-photon polymerization technology and provide a simple and stable way for the micromachining of chiral microstructures, which may have a wide range of applications in optical tweezers, optical communications, and metasurfaces. Full article
(This article belongs to the Special Issue Optics and Photonics in Micromachines)
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<p>Schematic diagram of tight focusing of MHCBs.</p> Full article ">Figure 2
<p>Phase distributions of (<b>a</b>) MHCBs with <math display="inline"><semantics> <mrow> <mi>K</mi> <mo>=</mo> <mn>0</mn> <mo>,</mo> <mi>m</mi> <mo>=</mo> <mn>1</mn> <mo>,</mo> <mi>α</mi> <mo>=</mo> <mn>6</mn> </mrow> </semantics></math> and (<b>b</b>) MHCBs with <math display="inline"><semantics> <mrow> <mi>K</mi> <mo>=</mo> <mn>0</mn> <mo>,</mo> <mi>m</mi> <mo>=</mo> <mn>3</mn> <mo>,</mo> <mi>α</mi> <mo>=</mo> <mn>6</mn> </mrow> </semantics></math>.</p> Full article ">Figure 3
<p>Experimental setup for laser direct writing by MHCBs. Other notations are: HWP, half-wave plate; PBS, polarized beam splitter; M, mirror; SLM, spatial light modulator; QWP, quarter-wave plate; L, lens; AOM, acoustic–optical modulator; PR, prism reflector; OL, objective lens; DM, dichromatic mirror; ND, neutral density filter.</p> Full article ">Figure 4
<p>Simulated light field of MHCBs at the focal region of high numerical aperture (NA = 1.45) oil-immersion objective lens. From top to bottom, the tightly focused MHCBs with parameter (<b>a1</b>–<b>a5</b>) <math display="inline"><semantics> <mrow> <mi>m</mi> <mo>=</mo> <mn>1</mn> <mo>,</mo> <mi>α</mi> <mo>=</mo> <mn>6</mn> </mrow> </semantics></math> and (<b>b1</b>–<b>b5</b>) <math display="inline"><semantics> <mrow> <mi>m</mi> <mo>=</mo> <mn>3</mn> <mo>,</mo> <mi>α</mi> <mo>=</mo> <mn>6</mn> </mrow> </semantics></math>. Simulated cross-sectional intensity profiles for the MHCBs at different positions through the objective lens (<b>a1</b>,<b>b1</b>) <math display="inline"><semantics> <mrow> <mi>z</mi> <mo>=</mo> <mo>−</mo> <mn>2</mn> <mi>λ</mi> </mrow> </semantics></math>, (<b>a2</b>,<b>b2</b>) <math display="inline"><semantics> <mrow> <mi>z</mi> <mo>=</mo> <mo>−</mo> <mi>λ</mi> </mrow> </semantics></math>, (<b>a3</b>,<b>b3</b>) <math display="inline"><semantics> <mrow> <mi>z</mi> <mo>=</mo> <mn>0</mn> </mrow> </semantics></math>, (<b>a4</b>,<b>b4</b>) <math display="inline"><semantics> <mrow> <mi>z</mi> <mo>=</mo> <mi>λ</mi> </mrow> </semantics></math>, (<b>a5</b>,<b>b5</b>) <math display="inline"><semantics> <mrow> <mi>z</mi> <mo>=</mo> <mn>2</mn> <mi>λ</mi> </mrow> </semantics></math>.</p> Full article ">Figure 5
<p>Measured and numerical calculated intensity profiles of MHCBs with parameter (<b>a</b>,<b>c</b>) <math display="inline"><semantics> <mrow> <mi>m</mi> <mo>=</mo> <mn>1</mn> <mo>,</mo> <mi>α</mi> <mo>=</mo> <mn>6</mn> </mrow> </semantics></math> and (<b>b</b>,<b>d</b>) <math display="inline"><semantics> <mrow> <mi>m</mi> <mo>=</mo> <mn>3</mn> <mo>,</mo> <mi>α</mi> <mo>=</mo> <mn>6</mn> </mrow> </semantics></math> at the focal plane of the objective lens.</p> Full article ">Figure 6
<p>The 3D structure of light field of the MHCBs and corresponding fabricated chiral structure. The 3D intensity distribution of the MHCBs with (<b>a</b>) <math display="inline"><semantics> <mrow> <mi>m</mi> <mo>=</mo> <mn>1</mn> <mo>,</mo> <mi>α</mi> <mo>=</mo> <mn>6</mn> </mrow> </semantics></math> and (<b>d</b>) <math display="inline"><semantics> <mrow> <mi>m</mi> <mo>=</mo> <mn>3</mn> <mo>,</mo> <mi>α</mi> <mo>=</mo> <mn>6</mn> </mrow> </semantics></math>. SEM photos of the fabricated 3D chiral microstructures via tightly focused MHCBs with (<b>b</b>) <math display="inline"><semantics> <mrow> <mi>m</mi> <mo>=</mo> <mn>1</mn> <mo>,</mo> <mi>α</mi> <mo>=</mo> <mn>6</mn> </mrow> </semantics></math> and (<b>e</b>) <math display="inline"><semantics> <mrow> <mi>m</mi> <mo>=</mo> <mn>3</mn> <mo>,</mo> <mi>α</mi> <mo>=</mo> <mn>6</mn> </mrow> </semantics></math>. SEM photos of the fabricated 3D chiral microstructures array via MHCBs with (<b>c</b>) <math display="inline"><semantics> <mrow> <mi>m</mi> <mo>=</mo> <mn>1</mn> <mo>,</mo> <mi>α</mi> <mo>=</mo> <mn>6</mn> </mrow> </semantics></math> and (<b>f</b>) <math display="inline"><semantics> <mrow> <mi>m</mi> <mo>=</mo> <mn>3</mn> <mo>,</mo> <mi>α</mi> <mo>=</mo> <mn>6</mn> </mrow> </semantics></math>.</p> Full article ">Figure 7
<p>SEM photos of the fabricated 3D chiral microstructures under different exposure times. (<b>a</b>) The exposure time increases with a step of 50 ms along the white arrow. (<b>b</b>) Two Chiral microstructures were fabricated under an exposure time of 50 ms.</p> Full article ">Figure A1
<p>SEM photo of 3D chiral microstructure fabricated by conventional point-by-point scanning TPP.</p> Full article ">
12 pages, 5694 KiB  
Article
Investigation of a 4H-SiC Trench MOSFET with Back-Side Super Junction
by Lili Zhang, Yuxuan Liu, Junpeng Fang and Yanjuan Liu
Micromachines 2022, 13(10), 1770; https://doi.org/10.3390/mi13101770 - 18 Oct 2022
Cited by 1 | Viewed by 2574
Abstract
In this paper, a 4H-SiC trench gate MOSFET, featuring a super junction layer located on the drain-region side, is presented to enhance the breakdown voltage and the figures of merit (FOM). The proposed structure is investigated and compared with the conventional structure with [...] Read more.
In this paper, a 4H-SiC trench gate MOSFET, featuring a super junction layer located on the drain-region side, is presented to enhance the breakdown voltage and the figures of merit (FOM). The proposed structure is investigated and compared with the conventional structure with a 2D numerical simulator—ATLAS. The investigation results have demonstrated that the breakdown voltage in the proposed structure is enhanced by 21.2%, and the FOM is improved by 39.6%. In addition, the proposed structure has an increased short-circuit capability. Full article
(This article belongs to the Special Issue Semiconductor Power Devices: Reliability and Applications)
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Figure 1

Figure 1
<p>Cross-sectional schematic of a half-cell in (<b>a</b>) C-UMOS and (<b>b</b>) BSJ-UMOS.</p> Full article ">Figure 2
<p>A possible fabrication process for BSJ-UMOS (<b>a</b>) growth of the n-pillar layer on n+ substrate (<b>b</b>) growth of the p-pillar layer by ion implantation (<b>c</b>) growth of the n-drift layer (<b>d</b>) growth of the p-body, n+ source and p+ contact regions (<b>e</b>) forming the trench gate structure (<b>f</b>). metalizing all contacts.</p> Full article ">Figure 3
<p>Comparison of I-V characteristic curves.</p> Full article ">Figure 4
<p>Distributions of current flowlines at <span class="html-italic">J</span><sub>ds</sub> = 100 A/cm<sup>2</sup> in (<b>a</b>) C-UMOS and (<b>b</b>) BSJ-UMOS.</p> Full article ">Figure 5
<p>Comparisons of transfer and breakdown characteristics.</p> Full article ">Figure 6
<p>Electric field distributions at <span class="html-italic">V</span><sub>gs</sub> = 0 V and <span class="html-italic">V</span><sub>ds</sub> = BV in (<b>a</b>) C-UMOS and (<b>b</b>) BSJ-UMOS.</p> Full article ">Figure 7
<p>Electric field distributions of the BSJ-UMOS and C-UMOS along the AA’ (<span class="html-italic">x</span> = 0.5 μm) and BB’ (<span class="html-italic">x</span> = 2.0 μm) lines, as shown in <a href="#micromachines-13-01770-f005" class="html-fig">Figure 5</a>a.</p> Full article ">Figure 8
<p>Electric field distributions of BSJ-UMOS and C-UMOS along CC’ (<span class="html-italic">y</span> = 3.4 μm), DD’ (<span class="html-italic">y</span> = 6.0 μm) and EE’ (<span class="html-italic">y</span> = 11 μm) lines, as shown in <a href="#micromachines-13-01770-f005" class="html-fig">Figure 5</a>b.</p> Full article ">Figure 9
<p>Comparisons of the parasitic capacitance in C-UMOS and BSJ-UMOS.</p> Full article ">Figure 10
<p>Depletion distributions of (<b>a</b>) C-UMOS and (<b>b</b>) BSJ-UMOS at <span class="html-italic">V</span><sub>ds</sub> = 70 V and <span class="html-italic">V</span><sub>gs</sub> = 0 V.</p> Full article ">Figure 11
<p>Comparisons of the gate charge performances.</p> Full article ">Figure 12
<p>Effect of concentration of the p-pillar and n-pillar on the BV and <span class="html-italic">R</span><sub>on,sp</sub>.</p> Full article ">Figure 13
<p>Effect of the concentration of the p-pillar and n-pillar on the BV and FOM.</p> Full article ">Figure 14
<p>Relationship curves of BV, <span class="html-italic">R</span><sub>on,sp</sub> and FOM versus charge imbalance for BSJ-UMOS.</p> Full article ">Figure 15
<p>Test circuit of the short-circuit performance.</p> Full article ">Figure 16
<p>Maximum lattice temperature and drain current for the short-circuit case.</p> Full article ">
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