CN111044184A - Silicon Micro/Nanowire-Based Miniaturized Large-Range Strain Sensor and Its Applications - Google Patents
Silicon Micro/Nanowire-Based Miniaturized Large-Range Strain Sensor and Its Applications Download PDFInfo
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- G—PHYSICS
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- G01L1/00—Measuring force or stress, in general
- G01L1/18—Measuring force or stress, in general using properties of piezo-resistive materials, i.e. materials of which the ohmic resistance varies according to changes in magnitude or direction of force applied to the material
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B81—MICROSTRUCTURAL TECHNOLOGY
- B81B—MICROSTRUCTURAL DEVICES OR SYSTEMS, e.g. MICROMECHANICAL DEVICES
- B81B7/00—Microstructural systems; Auxiliary parts of microstructural devices or systems
- B81B7/0032—Packages or encapsulation
- B81B7/007—Interconnections between the MEMS and external electrical signals
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B81—MICROSTRUCTURAL TECHNOLOGY
- B81C—PROCESSES OR APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OR TREATMENT OF MICROSTRUCTURAL DEVICES OR SYSTEMS
- B81C1/00—Manufacture or treatment of devices or systems in or on a substrate
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
- G01L1/00—Measuring force or stress, in general
- G01L1/20—Measuring force or stress, in general by measuring variations in ohmic resistance of solid materials or of electrically-conductive fluids; by making use of electrokinetic cells, i.e. liquid-containing cells wherein an electrical potential is produced or varied upon the application of stress
- G01L1/22—Measuring force or stress, in general by measuring variations in ohmic resistance of solid materials or of electrically-conductive fluids; by making use of electrokinetic cells, i.e. liquid-containing cells wherein an electrical potential is produced or varied upon the application of stress using resistance strain gauges
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B81—MICROSTRUCTURAL TECHNOLOGY
- B81B—MICROSTRUCTURAL DEVICES OR SYSTEMS, e.g. MICROMECHANICAL DEVICES
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Abstract
本发明涉及一种基于硅微/纳米线的微型化大量程应变传感器及其制备方法。该应变传感器包括柔性高分子基底层，功能层和封装层；功能层位于柔性高分子基底层上，封装层将功能层封装于柔性高分子基底层上；功能层包括波浪结构的硅微/纳米线以及设置在其两端的金属电极和引线。本发明还公开了其制备方法，首先利用预拉伸的高分子基底使硅微/纳米线形成波浪形可拉伸结构，然后用波浪结构的硅微/纳米线作为功能层制备微型化大量程应变传感器。本发明传感器具有较大的应变检测范围，良好的稳定性和可逆性，高耐用性，且体积小，轻便，其制备方法操作简单，成本低，对于人体行为监测传感器的应用具有重要意义。
The invention relates to a miniaturized large-scale strain sensor based on silicon micro/nano wire and a preparation method thereof. The strain sensor includes a flexible polymer base layer, a functional layer and an encapsulation layer; the functional layer is located on the flexible polymer base layer, and the encapsulation layer encapsulates the functional layer on the flexible polymer base layer; the functional layer comprises silicon micro/nano with a wave structure wire and metal electrodes and leads provided at both ends thereof. The invention also discloses a preparation method thereof. First, a pre-stretched polymer substrate is used to form a wavy stretchable structure of silicon micro/nano wires, and then a large-scale miniaturization is prepared by using the silicon micro/nano wires with wavy structure as a functional layer. strain sensor. The sensor of the invention has a large strain detection range, good stability and reversibility, high durability, small size, light weight, simple operation and low cost, and is of great significance for the application of human behavior monitoring sensors.
Description
Technical Field
The invention relates to a sensor, in particular to a miniaturized large-range strain sensor based on silicon micro/nano wires and application thereof.
Background
The wide-range strain sensor has great significance in the fields of wearable flexible electronic application, electronic skin, personal health monitoring and the like, and is closely concerned by extensive researchers. In recent years, researchers have produced a variety of flexible wearable strain sensors that can be used in medical and motion monitoring applications by developing new stretchable electrical materials and structures. For example, sensors based on composite elastic films are used to monitor finger joint movement and application to artificial skin (ACS Nano2014,8,4689; CN 103959029B); joint motion sensors based on supramolecular organic polymer films are used on robots as elbow joint motion monitoring (Nature nanotech.2012,7,825). These nanocomposite structure based flexible strain sensors all have good stretchability and durability. However, these flexible strain sensors made of composite structural materials generally have a large size, and they need to be attached to the surface of the human body by means of an adhesive tape or the like, limiting the movement of the user to some extent, and causing inconvenience to daily life. Electronic skin requires the integration of miniaturized stretchable sensors for sensing various internal and external signals of the human body without affecting daily life and human activities, however, there is no report on miniaturized wide-range strain sensors currently available for electronic skin applications.
Sensors based on semiconductor materials, such as conventional silicon materials, generally have excellent properties, e.g. a large response coefficient, a small response time and excellent mechanical stability. However, sensors based on semiconductor bulk materials are rigid and brittle, making flexible wearable applications difficult to implement, especially in terms of strain sensing, strain sensors based on single crystal silicon do not scale beyond 1% and are difficult to use for large scale strain sensing. CN 104501840A discloses a single super-long one-dimensional silicon micro/nano structure joint motion sensor and a preparation method thereof, but because the super-long one-dimensional silicon micro/nano structure cannot be stretched, the maximum strain cannot exceed 1.5%, and the strain detection range of the sensor is still low. CN 110118621A discloses a self-repairing flexible pressure sensor and a manufacturing method thereof, wherein a first electrode of the pressure sensor is a self-repairing polyurethane film containing a silver nanowire layer or a gold layer, and the first electrode is provided with a wavy microstructure, the structure can reduce the elastic resistance of a polymer and increase the capacitance change of the pressure sensor when the pressure sensor is stressed, so that the sensitivity of the pressure sensor is improved, but the pressure sensor and a strain sensor detection principle have great difference, so that a common pressure sensor cannot be used for strain detection, and the pressure sensor is not exceptional. Therefore, it is necessary to develop a miniaturized, large-scale strain sensor.
Disclosure of Invention
In order to solve the technical problems, the invention aims to provide a miniaturized wide-range strain sensor based on silicon micro/nanowires and application thereof.
In order to achieve the purpose, the invention adopts the following technical scheme:
the invention relates to a silicon micro/nano wire based miniaturized wide-range strain sensor, which comprises a flexible high-molecular substrate layer with a flat surface, a functional layer arranged on the flexible high-molecular substrate layer and an encapsulation layer encapsulating the functional layer on the flexible high-molecular substrate layer; the functional layer comprises at least one silicon micro/nano wire in a regular wave-shaped structure, and metal electrodes and leads arranged at two ends of the silicon micro/nano wire, wherein one end of the lead is connected with the metal electrodes, and the other end of the lead is positioned outside the packaging layer.
Furthermore, the length of the silicon micro/nano wire is less than 100mm, and the diameter is 0.05-10 μm. Preferably, the length of the silicon micro/nanowires is 5-100 mm. The length of a common silicon micro/nano wire is in a micron order, the deformation of human skin is often uneven, the device cannot effectively sense the deformation of the skin by adopting the silicon micro/nano wire with the common length, and the silicon micro/nano wire with the length of 5-100mm can meet the requirement of covering common joints and can effectively monitor joint movement. The diameter of 0.05-10 μm ensures that the radial dimension is smaller than the resolution of human eyes, so the silicon micro/nano wire is not easy to be distinguished by human eyes on a macroscopic scale, and the invisible effect of the silicon micro/nano wire can be realized. In addition, silicon micro/nanowires with too large a diameter (>10 μm) are difficult to fabricate into wavy structures and corresponding flexible devices due to their rigidity and brittleness.
Preferably, in the miniaturized wide-range strain sensor, the number of the silicon micro/nanowires is one, and the silicon micro/nanowires are monocrystalline silicon micro/nanowires.
Further, the strain detection range of the sensor is 0% -100%.
Furthermore, the material of the flexible polymer substrate layer and the material of the encapsulation layer are respectively and independently selected from Polydimethylsiloxane (PDMS), polyethylene terephthalate, polypropylene, polyvinyl chloride or polyacrylic resin. When used as a flexible polymer substrate layer, the above polymers all have a small young's modulus close to that of the skin, and can be conformally contacted with the skin by van der waals force. By using these materials as the substrate, the micro strain sensor can have good flexibility without incurring high manufacturing costs. In addition, the polymers have good adhesion, flexibility, acid and alkali corrosion resistance and good air tightness. When the materials are used as the packaging layer, the flexibility of the sensor is not influenced after packaging, and the normal work of the sensor under severe external environment conditions can be ensured.
Further, the thicknesses of the flexible polymer substrate layer and the encapsulation layer are respectively and independently selected from 1-500 μm. The miniaturization of the whole size of the device can be guaranteed due to the thin size, the conformal contact between the micro strain sensor and the skin can be better guaranteed, and the skin can be well adapted to the wrinkles of the skin.
In the invention, the flexible polymer substrate layer has a flat surface, i.e. the surface of the flexible polymer substrate layer is not provided with any wrinkles, and particularly the surface of the flexible polymer substrate layer on the side contacting with the silicon micro/nano wire is flat.
Furthermore, the metal electrode is made of silver paste, indium-gallium alloy or carbon-based conductive adhesive. Preferably, the metal electrode is made of indium-gallium alloy.
Furthermore, one end of the lead wire positioned outside the packaging layer is connected with a circuit acquisition unit, and the circuit acquisition unit is used for acquiring an electric signal of the strain sensor in the strain process.
Furthermore, the circuit acquisition unit is a current acquisition unit.
The invention also discloses a preparation method of the miniaturized large-range strain sensor based on the silicon micro/nano wire, which comprises the following steps:
(1) transferring at least one (preferably single) silicon micro/nano wire to the surface of a pre-stretched semi-cured flexible polymer substrate layer in an aligned state;
(2) after the flexible polymer substrate layer is completely cured, releasing the strain applied on the flexible polymer substrate layer so that the silicon micro/nano wires form a regular wavy structure along with the shrinkage of the flexible polymer substrate layer;
(3) respectively preparing metal electrodes at two ends of the silicon micro/nano wire processed in the step (2), and connecting a lead on the metal electrodes to form a functional layer;
(4) and packaging the flexible polymer substrate layer and the functional layer by using a packaging material, wherein one end of the lead wire, which is far away from the metal electrode, is positioned outside the packaging material, so that the silicon micro/nano wire-based miniaturized wide-range strain sensor is obtained.
Further, in the step (1), the pre-stretching strain of the semi-cured flexible polymer substrate layer is 5% -100%. And (3) changing the wave structure in the step (2) along with the change of the prestretching amount applied to the flexible polymer substrate layer, thereby obtaining the strain sensor with different measuring ranges.
Further, in the step (1), the silicon micro/nano wires are transferred to the surface of the pre-stretched semi-cured flexible polymer substrate layer in a friction alignment state on the flexible polymer substrate layer by a contact printing method until the silicon micro/nano wires are transferred to the flexible polymer substrate layer in an alignment manner. The silicon micro/nano wire has good flexibility, is easy to bend and even knot, the regularity of the subsequent device structure design can be influenced by bending or knotting, the regularity of the structure obtained in the subsequent structure design can be fully ensured by the ultra-long silicon micro/nano wire after the collimation step, and the sensing can be carried out by utilizing the larger length of the ultra-long silicon micro/nano wire.
Further, in the step (3), a coating method, a thermal evaporation method, an electron beam evaporation method or a magnetron sputtering method is used to prepare the metal electrode.
Preferably, in the step (3), the indium gallium alloy is coated by a coating method to prepare a metal electrode. The liquid property of the indium gallium alloy can ensure that the indium gallium alloy and the silicon micro/nano wire form good electrode contact, can flow along with the stretching of the substrate when large stretching strain is applied, and cannot be separated from the silicon micro/nano wire under the condition of large stretching amount, so that the human motion response recorded by the device can be stably led out through an electric signal.
Further, before the step (1) and the step (3), the silicon micro/nano wire can be pretreated by hydrofluoric acid solution. The mass content of solute in the hydrofluoric acid solution is 1-10%. Preferably, the hydrofluoric acid solution treatment time is 1-10 min. The hydrofluoric acid solution pretreatment can prevent the silicon micro/nano wire from being embedded in the semi-solidified flexible high polymer substrate layer when being transferred to the semi-solidified flexible high polymer substrate layer, and can etch part of high polymer near the silicon micro/nano wire so as to form a conductive loop by subsequently preparing electrode contact. When the flexible polymeric substrate layer is cured to a moderate degree, the silicon micro/nanowires are not embedded when transferred to its surface, and no pre-treatment with hydrofluoric acid solution is required.
The silicon micro/nano wire is used as a semiconductor and has rigidity and brittleness, and the silicon micro/nano wire is designed into a wave-shaped structure, and the structure is formed by fixing the silicon micro/nano wire on a semi-solidified pre-stretched flexible high polymer substrate layer to form a regular wave-shaped structure after stress is released. The wavy structure can convert tensile deformation into bending deformation of the wavy structure, so that the silicon micro/nano wire cannot be damaged under the condition of large tensile force, the stretchability of the silicon micro/nano wire is improved, and the flexible high-molecular substrate layer is still flat after tensile strain is released. The structure of the micro/nano wire is controlled through the prestretching of the flexible high-molecular substrate layer, and the micro/nano wire is endowed with larger stretchability, so that the operation is simple, the structure regulation and control are facilitated, and the strain sensors with different strain detection ranges are obtained.
The invention also discloses application of the silicon micro/nanowire-based miniaturized wide-range strain sensor as a flexible strain sensor or a wearable device.
Further, the strain detection range of the flexible strain sensor is 0% -100%.
Further, the flexible strain sensor can sense micro-motions such as human joint motion and swallowing.
Further, the wearable device may act as a strain sensor for detecting human body movements.
In the present invention, "silicon micro/nanowire" refers to "silicon micro-wire or silicon nanowire".
By the scheme, the invention at least has the following advantages:
the invention selects the micro/nano wires to improve the flexibility of the semiconductor, endows the semiconductor with high stretchability through structural design, and still can maintain good electrical and mechanical properties of the semiconductor material. The miniaturized wide-range strain sensor has a small size, can be attached to the skin of a human body in a conformal mode, has high sensitivity and stability, can be used for electronic skin application, and can sense small motions such as joint large-range movement and swallowing at the same time, and most other strain sensors are difficult to achieve.
In the aspect of performance, the sensor has a large strain detection range, good stability and reversibility and high durability; in the aspect of practicality, the sensor is small, and is light, can be conformal combine with human skin, let the people be difficult to perceive and the perception, can regard as wearable device's important component, carry out the sensing to various human activities.
The preparation method of the strain sensor is simple to operate and low in cost, and has important significance for the application of the human behavior monitoring sensor.
The foregoing description is only an overview of the technical solutions of the present invention, and in order to make the technical solutions of the present invention more clearly understood and to implement them in accordance with the contents of the description, the following description is made with reference to the preferred embodiments of the present invention and the accompanying detailed drawings.
Drawings
Fig. 1 is a schematic structural diagram of a miniaturized wide-range strain sensor based on a single ultra-long silicon micro/nanowire.
Fig. 2 is a photomicrograph mosaic of single ultra-long silicon micro/nanowires prepared in example 2 and an SEM of the diameter of the ultra-long silicon micro/nanowires.
Fig. 3 is a photomicrograph of a single ultra-long silicon micro/nanowire-based miniaturized wide range strain sensor mosaic and microscopic contact points of indium gallium alloy and silicon micro/nano.
Fig. 4 is a current-time curve obtained by applying a strain from 0% to 45% and gradually recovering for a miniaturized wide-range strain sensor based on a single ultra-long silicon micro/nanowire prepared in example 2.
Fig. 5 is a photograph of a miniaturized wide-range strain sensor based on a single ultra-long silicon micro/nanowire prepared in example 2 for sensing various motions of a human body.
Fig. 6 is a schematic diagram of strain detection of four miniaturized wide-range strain sensors based on single ultra-long silicon micro/nano-wires, which are prepared under the conditions that the pre-strain of the flexible high polymer substrate layer is 10%, 20%, 35% and 50% respectively.
Description of reference numerals:
1-an encapsulation layer; 2-a metal electrode; 3-silicon micro/nanowires; 4-a flexible polymeric substrate layer; 5-lead wire.
Detailed Description
The following examples are given to further illustrate the embodiments of the present invention. The following examples are intended to illustrate the invention but are not intended to limit the scope of the invention.
The experimental methods described in the following examples are all conventional methods unless otherwise specified; the reagents and materials used, unless otherwise indicated, are commercially available.
Example 1
The embodiment provides a joint motion sensor based on a single ultra-long silicon micro/nanowire, and the structural schematic diagram of the joint motion sensor is shown in fig. 1. The sensor consists of the following components: the flexible high polymer substrate layer 4 is arranged on the functional layer on the flexible high polymer substrate layer and the packaging layer 1 is used for packaging the functional layer on the flexible high polymer substrate layer; the functional layer comprises a single wave-structure ultra-long silicon micro/nanowire 3 after structural design, and metal electrodes 2 and leads 5 arranged at two ends of the silicon micro/nanowire. One end of the lead 5 is connected with the metal electrode 2, and the other end of the lead 5 is positioned outside the packaging layer 1.
Example 2
The embodiment provides a preparation method of a miniaturized wide-range strain sensor based on a single ultra-long silicon micro/nanowire. The flexible polymer substrate layer used in this embodiment is made of Polydimethylsiloxane (PDMS) with a thickness of 100 μm; the hydrofluoric acid solution is a dilute aqueous solution with solute mass concentration of 5%; the material of the packaging layer is polydimethylsiloxane (PDMS, Dow Corning SYLGARD 184).
The equipment used for preparing the ultra-long silicon micro/nano wires used in the embodiment is a vacuum tube furnace, which is produced by the combined fertilizer science crystal material technology limited company, a furnace tube of the vacuum tube furnace is a corundum tube, and the inner diameter of the corundum tube is 37.44mm, and the outer diameter of the corundum tube is 44.3 mm. The pharmaceutical Silicon monoxide (SiO) powder used was Silicon monoxide (si — n) powder, 325mesh (aldrich chemical), CAS: 10097-28-6, Fw (formula weight): 44.09, d (density): 2.13g/mL from sigma-aldrich; tin powder (200 mesh) was purchased from national pharmaceutical group chemicals limited, CAS: 7440-31-5.
The preparation method of the miniaturized large-range strain sensor based on the single ultra-long silicon micro/nanowire comprises the following steps:
1. and preparing the ultra-long silicon micro/nanowire with the length of 1 cm. Taking 0.5g of SiO powder, placing the powder in porcelain boats, placing the porcelain boats in a high-temperature area of a vacuum tube furnace, taking 70g of tin powder, placing the two porcelain boats in two porcelain boats respectively, placing the two porcelain boats in two side areas of a high-temperature center respectively, enabling one end of each porcelain boat, which is close to the high-temperature area, to be 7cm away from the high-temperature center, sealing the vacuum tube furnace, exhausting air until the pressure in a furnace chamber is lower than 0.5Pa, and sealing a vacuum tube. Heating the high-temperature area of the furnace chamber to 1330 ℃ at the speed of 15 ℃/min, keeping the temperature at 1330 ℃ for 60min, and then naturally cooling to room temperature; filling air into the furnace chamber to atmospheric pressure, wherein the gas flow is 300 sccm; and opening the furnace chamber, and obtaining the ultra-long silicon micro/nano wire with the length of 1cm on the ceramic boat wall at the position 9-11cm away from the high-temperature center.
2. The method comprises the following steps of clamping an ultra-long silicon micro/nano wire by using a pointed-end tweezers, enabling the ultra-long silicon micro/nano wire to slowly pass through hydrofluoric acid liquid drops with mass concentration of 5%, enabling the free end of the ultra-long silicon micro/nano wire to fall onto a silicon wafer substrate, and then pulling the ultra-long silicon micro/nano wire to one side to enable the whole nano wire to be placed on the silicon wafer substrate in an.
3. And (3) proportioning the PDMS monomer A and the curing agent B according to the proportion of 10:1 to obtain a PDMS solution. And (3) spin-coating a PDMS solution on a flat surface to form a PDMS layer with the thickness of 100 microns, placing the PDMS layer in a 75 ℃ oven for two hours to be cured, spin-coating a thin PDMS layer (with the thickness of 5 microns) on the PDMS solution, placing the PDMS layer in the 75 ℃ oven for one hour to be semi-cured, and taking a part of the obtained product as a flexible polymer substrate layer material.
4. The semi-cured PDMS base layer was removed and a quantitative pre-stretch was applied, with a pre-stretch of 50%.
5. And (3) contacting the ultra-long silicon micro/nano wires on the silicon chip in the step (2) with the semi-cured flexible polymer substrate layer in the step (4) by using a contact printing method until the single silicon micro/nano wires are transferred to the flexible polymer substrate layer from the silicon chip in an aligned manner.
6. After the semi-cured flexible high polymer substrate layer with the aligned ultra-long silicon micro/nano wires on the surface is completely cured in an oven at 75 ℃, the strain applied by pre-stretching is released, after the strain applied by pre-stretching is released, the ultra-long silicon micro/nano wires form a regular wave-shaped structure, and after the tensile strain is released, the flexible high polymer substrate layer is still flat.
7. After the silicon micro/nano wire is treated by hydrofluoric acid solution, indium gallium alloy electrodes are coated at two ends of the silicon micro/nano wire, and the silicon micro/nano wire is led out by a lead.
8. And (3) spin-coating the PDMS solution prepared in the step (3) on the silicon micro/nano wire and the indium-gallium alloy electrode, covering the upper surface of the whole device, and placing the device in a 75 ℃ oven for two hours for curing to form a packaging layer.
The miniaturized large-range strain sensor based on the single ultra-long silicon micro/nanowire is obtained through the steps.
For the miniaturized wide-range strain sensor prepared in example 2, an optical microscope is used for characterizing the structure of the device, and the electromechanical response characteristics of the sample and the response of the device when the strain sensor is used for sensing human joint motion are tested.
Firstly, SEM analysis is carried out on the single ultra-long silicon micro/nanowire prepared in the step 1, and the length of the silicon micro/nanowire is 1cm (figure 2a), and the diameter of the silicon micro/nanowire is 600nm (figure 2 b). Microscopic analysis is carried out on a miniaturized wide-range strain sensor based on a single ultra-long silicon micro/nanowire, the effective length of a silicon micro/nanowire sensing part and the contact condition of the silicon micro/nanowire sensing part and an indium gallium electrode are confirmed, the obtained microscopic picture is jigsaw shown in figure 3a, the fact that the sensing effective length of the silicon micro/nanowire is 5mm, effective contact between the silicon micro/nanowire and the indium gallium alloy electrode is achieved (figure 3b), and in figure 3, an arrow points to the silicon micro/nanowire.
And (3) performing electromechanical response test on the sensor obtained in the step (8), adding-10V direct-current voltage on electrodes at two ends of the device by using an electrochemical workstation (Shanghai Chenghua CHI660E), recording a current-time curve, applying strain from 0% to 45% to the micro strain sensor in the test process, and gradually recovering, wherein the obtained current-time curve is shown in figure 4, and the test result shows that the device can stably and quickly distinguish different stretching amounts and has good stability and reversibility.
The effective sensing length of the miniaturized wide-range strain sensor based on the single ultra-long silicon micro/nanowire prepared by the embodiment is 5mm, and the sensor can effectively sense the joint movement, swallowing and the like of a human body. The sensor is naturally attached to the surface of the skin of a human body, and fig. 5 records the change of the current of the sensor when the sensor performs motion detection at different positions on the surface of the human body. The sensor prepared above was attached to the inner side of the wrist, the wrist was bent upward and downward, and the process was repeated a plurality of times (fig. 5a), the current change of the sensor was detected, and the resistance change rate thereof was calculated (fig. 5 b). At the same time, the sensor prepared above was attached near the laryngeal prominence (fig. 5c), and the swallowing action was repeated to calculate the rate of change in resistance of the sensor (fig. 5 d). It can be seen that the sensor can effectively monitor various movements of the human body.
In addition, sensors with different strain detection ranges can be prepared according to the above method, except that in step 4, the pre-stretching amounts of the PDMS base layer are 10%, 20%, and 35%, respectively. Under different pre-stretching amounts, the strain detection range of the strain sensor prepared by the invention is shown in fig. 6, and the result shows that the larger the pre-stretching amount is, the larger the strain detection range of the device is; and each strain sensor has the best sensitivity when detecting the strain close to the pre-stretching amount of the strain sensor, so that a user can flexibly select a proper sensor according to the strain range needing to be detected.
The results show that in the field of human body action sensors, the single ultra-long silicon micro/nanowire-based device has the advantages of being lighter, large in strain detection range, easy to integrate and the like, and has important significance for rapidly developing wearable application.
The above is only a preferred embodiment of the present invention, and is not intended to limit the present invention, it should be noted that, for those skilled in the art, many modifications and variations can be made without departing from the technical principle of the present invention, and these modifications and variations should also be regarded as the protection scope of the present invention.
Claims (10)
1. A miniaturized wide-range strain sensor based on silicon micro/nano wires is characterized in that: the flexible high polymer substrate comprises a flexible high polymer substrate layer, a functional layer arranged on the flexible high polymer substrate layer and an encapsulation layer encapsulating the functional layer on the flexible high polymer substrate layer; the functional layer comprises at least one silicon micro/nano wire in a wave-shaped structure, and metal electrodes and leads arranged at two ends of the silicon micro/nano wire, wherein one end of the lead is connected with the metal electrodes, and the other end of the lead is positioned outside the packaging layer.
2. The miniaturized, high-range strain sensor based on silicon micro/nanowires of claim 1, wherein: the length of the silicon micro/nano wire is less than 100mm, and the diameter is 0.05-10 mu m.
3. The miniaturized, high-range strain sensor based on silicon micro/nanowires of claim 1, wherein: the strain detection range of the sensor is 0-100%.
4. The miniaturized, high-range strain sensor based on silicon micro/nanowires of claim 1, wherein: the material of the flexible polymer substrate layer and the material of the packaging layer are respectively and independently selected from polydimethylsiloxane, polyethylene terephthalate, polypropylene, polyvinyl chloride or polyacrylic resin.
5. The miniaturized, high-range strain sensor based on silicon micro/nanowires of claim 1, wherein: the thicknesses of the flexible polymer substrate layer and the packaging layer are respectively and independently selected from 1-500 mu m.
6. The miniaturized, high-range strain sensor based on silicon micro/nanowires of claim 1, wherein: the metal electrode is made of silver adhesive, indium gallium alloy or carbon-based conductive adhesive.
7. A method for preparing a miniaturized high-range strain sensor based on silicon micro/nanowires as claimed in any one of claims 1 to 6, comprising the steps of:
(1) transferring the silicon micro/nano wire to the surface of a pre-stretched semi-cured flexible polymer substrate layer in a collimation state;
(2) after the flexible polymer substrate layer is completely cured, releasing strain applied to the flexible polymer substrate layer so that the silicon micro/nano wire forms a wavy structure along with the contraction of the flexible polymer substrate layer;
(3) respectively preparing metal electrodes at two ends of the silicon micro/nanowire treated in the step (2), and connecting a lead on the metal electrodes to form a functional layer;
(4) and packaging the flexible polymer substrate layer and the functional layer by using a packaging material, wherein one end of the lead wire, which is far away from the metal electrode, is positioned outside the packaging material, so that the silicon micro/nano wire based miniaturized wide-range strain sensor is obtained.
8. The method of claim 7, wherein: in the step (1), the pre-stretching strain of the semi-cured flexible polymer substrate layer is 5% -100%.
9. The method of claim 7, wherein: in the step (3), the metal electrode is prepared by a coating method, a thermal evaporation method, an electron beam evaporation method or a magnetron sputtering method.
10. Use of the silicon micro/nanowire-based miniaturized high range strain sensor of any of claims 1-6 as a flexible strain sensor or a wearable device.
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