Flexible omnidirectional sensor based on silver nanowire and liquid metal electrode and preparation method thereof

Abstract

The invention discloses a flexible omnidirectional sensor based on a silver nanowire and a liquid metal electrode and a preparation method of the flexible omnidirectional sensor, and relates to the technical field of flexible sensors. The sensor comprises a substrate layer and an encapsulation layer, and a plurality of sensing units and leads are arranged between the substrate layer and the encapsulation layer; the sensing unit is composed of a silver nanowire guide point line and liquid metal gallium indium alloy electrodes covering the two ends of the silver nanowire guide point line. The liquid metal gallium indium alloy electrodes are further provided with a plurality of leads leading to the outside of the sensor. The silver nanowire pattern realizes sensitive sensing of strain, and the gallium-indium alloy electrode realizes stable and reliable electric connection in a flexible strain process; the whole flexible device has good stretchability and stability, has high sensitivity, wide detection range and small lag, can realize real-time monitoring of tiny and violent human body movement, and can be applied to the fields of wearable equipment, flexible robots, electronic skin and the like.

Description

Technical Field

[0001] The present invention relates to the technical field of flexible sensors, in particular to a flexible omnidirectional sensor based on silver nanowires and liquid metal electrodes and a preparation method thereof. Background Art

[0002] With the development of intelligent modern society, the research on flexible smart wearable devices is increasing, and the demand for sensors with strong directionality, stability and the ability to detect small strains is increasing rapidly. Traditional metal electrode sensors have poor stability, while liquid metal gallium indium alloy has low viscosity and high conductivity at room temperature, and its room temperature fluidity is the key to the stable and rapid transmission of signals between various parts during the deformation of the sensor, so it has good stability and stretchability. Compared with complex omnidirectional sensors, flexible omnidirectional sensors based on silver nanowires and gallium indium alloy electrodes have received attention due to their good stretchability and stability of the conduction process.

[0003] Patent CN 114963962A discloses a method for preparing a flexible strain sensor based on AgNWs-Mxene, which uses AgNWs and Mxene as sensitive materials, and combines them with flexible substrate materials polydimethylsiloxane (PDMS) and triblock copolymer (SEBS) respectively to obtain two flexible strain sensors. The prepared strain sensors have the advantages of high sensitivity, high linearity, good stability, etc., and the electrode material is conductive tape. Patent CN 107655598B discloses a flexible stress sensor based on a composite conductive film of carbon nanotubes and silver nanowires, which is prepared by dispersing CNTs in ethanol and synthesizing AgNWs in the dispersed solution, and then using a spraying method to transfer the mixed solution of AgNWs and CNTs to a PDMS flexible substrate to prepare a composite conductive film conductive electrode of CNTs and AgNWs, and finally encapsulating it with a layer of PDMS flexible substrate. The electrode material used is a gold electrode. Patent CN 111141427A discloses a method for preparing a wearable transparent flexible thin film strain sensor, comprising depositing polymethylsiloxane (PDMS) onto a treated polyethylene terephthalate (PET) substrate, and then depositing Ti3C2T x MXene dispersion and silver nanowire (AgNWs) dispersion were sprayed or spin-coated onto the surface of the formed polydimethylsiloxane (PDMS) film, and the sample was peeled off from the PET substrate to obtain AgNWs / Ti3C2T x MXene / PDMS transparent flexible conductive film, whose electrode material is metal electrode.

[0004] These reported silver nanowire flexible strain sensors all use rigid materials such as metal sheets and copper wires as electrodes, which cannot meet the requirements of applying a large amount of complex dynamically changing stresses. They are prone to breakage under the destructive action of external forces, resulting in sensor failure. At the same time, when the flexible sensor is stretched as a whole, since the rigid material electrode cannot deform together with the sensing part, the interface between the electrode and the silver nanowire is subjected to greater stress, which will cause greater fluctuations in the measurement of the sensing signal. In addition, long-term use of metal electrodes (such as copper wires) will cause the silver nanowires to interact with the air and be corroded, shortening the service life of the sensor. These problems limit its application in wearable devices. Therefore, providing a flexible omnidirectional strain sensor has become a technical problem that needs to be solved urgently in this field. Summary of the invention

[0005] In view of the above problems, the present invention aims to provide a flexible omnidirectional sensor based on silver nanowires and liquid metal electrodes and a preparation method thereof, so as to meet the requirements of flexible devices for sensor stretchability, stability and omnidirectional sensing.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] First, the present application provides a flexible omnidirectional sensor based on silver nanowires and liquid metal electrodes, the sensor comprising a base layer and an encapsulation layer, wherein a plurality of sensing units and leads are arranged between the base layer and the encapsulation layer;

[0008] The sensing unit is composed of a silver nanowire guide line and a liquid metal gallium indium alloy electrode covering both ends of the silver nanowire guide line, and a plurality of leads leading to the outside of the sensor are also arranged in the liquid metal gallium indium alloy electrode; the silver nanowire guide line is preferably 0.5-1mm wide and 5-10mm long;

[0009] Preferably, the silver nanowire guide point line is obtained by depositing a silver nanowire dispersion and then drying it;

[0010] The above-mentioned base layer and encapsulation layer have the same structure, and are obtained by curing the polydimethylsiloxane prepolymer liquid, and their thickness is preferably 0.5-1mm;

[0011] The polydimethylsiloxane prepolymer solution is obtained after curing, which means that the polydimethylsiloxane monomer and the curing agent are mixed and stirred at room temperature for 5 to 10 minutes to obtain the polydimethylsiloxane prepolymer solution; the polydimethylsiloxane prepolymer solution is cured at room temperature or heated (70° C.) to form a base layer or an encapsulation layer. The curing agent is preferably 1-hydroxycyclohexyl phenyl ketone.

[0012] Secondly, the present application provides a method for preparing the above-mentioned flexible omnidirectional sensor based on silver nanowires and liquid metal electrodes, comprising the following steps:

[0013] 1) Mixing polydimethylsiloxane monomer and curing agent, stirring at room temperature for 5-10 minutes to obtain polydimethylsiloxane prepolymer solution, and letting it stand for 10-20 minutes for standby use;

[0014] The mass ratio of the polydimethylsiloxane monomer to the curing agent is 10:1;

[0015] The curing agent is preferably 1-hydroxycyclohexyl phenyl ketone;

[0016] 2) Preparing a template using polyimide tape: Take a glass slide, clean it with acetone, ethanol and deionized water, and then stick several strips of polyimide tape on the glass slide to obtain a template with a concave pattern.

[0017] These concave patterns are the shapes of the target sensing units. In specific implementations, several polyimide tapes can be used according to needs, such as 1, 2, 3, 4, etc. The edges of these polyimide tapes form concave patterns with the glass slide; or a hollow target pattern can be prepared on the surface of the polyimide tape, and then it can be pasted on the surface of the glass slide to form a template with a groove pattern. These patterns can be set according to actual needs.

[0018] In one embodiment of the present application, three polyimide tapes are adhered to the surface of a glass slide, and the three tapes present an unsealed equilateral triangle concave pattern on the surface of the glass slide; in another embodiment of the present application, two polyimide tapes with dumbbell-shaped hollow patterns are adhered to the surface of a glass slide to obtain a template with a dumbbell-shaped concave pattern.

[0019] 3) The polydimethylsiloxane prepolymer liquid is evenly coated on the surface of the template, and placed on a hot plate and heated at 70° C. for 2 hours (heating is performed to accelerate the curing of the polydimethylsiloxane prepolymer liquid). The polydimethylsiloxane prepolymer liquid forms a semi-solidified viscous base layer, and the base layer forms a groove at the template pattern.

[0020] Preferably, the groove depth is 0.1-0.5 mm, and the base layer thickness is 0.5-1 mm;

[0021] 4) Before the substrate layer is completely cured, apply the silver nanowire dispersion to the grooves of the substrate layer, and use an art brush to straighten the silver nanowire dispersion so that the nanowires are arranged in the same direction, and then place it on a hot stage at 70°C to dry for 3-5 minutes. Use the dried silver nanowire dispersion to deposit the silver nanowires in the grooves of the substrate layer. After the silver nanowire dispersion is dry, repeat the above process 3-5 times to form silver nanowire guide lines.

[0022] The silver nanowire dispersion is preferably a deionized water dispersion of silver nanowires, and the mass concentration of the silver nanowires is 10 mg / ml.

[0023] Preferably, the silver nanowire guide point line width is 0.5-1mm and the length is 5-10mm;

[0024] 5) After the silver nanowire guide point line is dried, liquid metal gallium indium alloy is dripped onto the surfaces of both ends of the silver nanowire guide point line in the groove to form liquid metal gallium indium alloy electrodes. The mass ratio of gallium to indium in the liquid metal gallium indium alloy is preferably 0.755:0.245. The silver nanowire guide point line and the liquid metal gallium indium alloy electrodes covering both ends thereof together form a sensing unit.

[0025] 6) Arrange several copper wires in the liquid metal gallium-indium alloy electrode to form leads to connect the sensor to external equipment. The diameter of the copper wire is 0.05-0.15 mm;

[0026] 7) The substrate layer and the upper surface of the electrode are uniformly covered with a layer of polydimethylsiloxane prepolymer prepared in step 1), and after the polydimethylsiloxane prepolymer is completely cured, an encapsulation layer is formed; the product is peeled off from the template surface to obtain the above-mentioned flexible omnidirectional sensor based on silver nanowires and liquid metal electrodes. The above-mentioned curing refers to standing at room temperature until the polydimethylsiloxane prepolymer is completely cured, or heating at 70°C until it is completely cured (about 3h). The thickness of the above-mentioned encapsulation layer is 0.5-1mm.

[0027] The flexible omnidirectional sensor based on silver nanowires and liquid metal electrodes in this application is composed of a silver nanowire strain sensing pattern and a corresponding flexible gallium-indium alloy electrode. The silver nanowire pattern realizes sensitive perception of strain, and the gallium-indium alloy electrode realizes stable and reliable electrical connection during flexible strain. The flexible device has good stretchability and stability as a whole, high sensitivity, wide detection range and small hysteresis, and can realize real-time monitoring of small and violent human body movements, and can be applied to wearable devices, flexible robots, electronic skin and other fields. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is a schematic diagram of the structure of a flexible omnidirectional sensor based on silver nanowires and liquid metal electrodes prepared in Example 1;

[0029] Among them, A is the plane view of the sensor, and B is the cross-sectional view of the sensor.

[0030] Figure 2 This is a physical picture of the flexible omnidirectional sensor based on silver nanowires and liquid metal electrodes prepared in Example 1.

[0031] Figure 3 This is a schematic diagram of the structure of a flexible omnidirectional sensor based on silver nanowires and liquid metal electrodes prepared in Example 2;

[0032] Among them, A is a schematic diagram of the template, and B is a schematic diagram of the sensor structure.

[0033] Figure 4 This is a resistance change diagram of the flexible omnidirectional sensor based on silver nanowires and liquid metal electrodes prepared in Example 1 when the stretching direction is horizontal and the stretching strain is 2%;

[0034] Figure 5 This is a graph showing the resistance change of the flexible omnidirectional sensor based on silver nanowires and liquid metal electrodes prepared in Example 1 when the stretching direction is 30° to the horizontal direction and the tensile strain is 2%;

[0035] Figure 6 This is a resistance change diagram of the flexible omnidirectional sensor based on silver nanowires and liquid metal electrodes prepared in Example 1 when the stretching direction is 60° to the horizontal direction and the tensile strain is 2%;

[0036] Figure 7 This is a graph showing the resistance change of the flexible omnidirectional sensor based on silver nanowires and liquid metal electrodes prepared in Example 1 when the stretching direction is 90° to the horizontal direction and the tensile strain is 2%;

[0037] Figure 8 This is a graph showing the resistance change of the flexible omnidirectional sensor based on silver nanowires and liquid metal electrodes prepared in Example 3 after 1000 cycles when the stretching direction is horizontal and the tensile strain is 1%.

[0038] In the figure, 1-base layer, 2,3,4-silver nanowire conductive lines, 5,6,7,8,9,10-liquid metal gallium indium alloy electrodes, 11-encapsulation layer, 12,13,14,15,16,17-leads, 18-polyimide tape, 19-glass slide, 20,21-concave patterns. DETAILED DESCRIPTION

[0039] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments. The embodiments are merely used to explain and illustrate the present invention, and the present invention is not limited to these embodiments.

[0040] The reagents and equipment used in the examples are commercially available.

[0041] Liquid metals used include gallium-indium alloy (gallium-indium mass ratio of 0.755:0.245), gallium-indium-tin alloy, sodium-potassium alloy, etc. purchased from Yuxin Alloy Co., Ltd., all of which are conventional liquid metal materials.

[0042] Silver nanowire aqueous dispersion was purchased from Shanghai Ouyi Organic Optoelectronic Materials.

[0043] Polydimethylsiloxane was purchased from Dow Corning Co.

[0044] The polyimide tape was purchased from Wangyang Tape.

[0045] The glass abrasives were purchased from Mingyang Quartz.

[0046] Example 1 Flexible omnidirectional sensor based on silver nanowires and liquid metal electrodes

[0047] The steps for preparing the flexible omnidirectional sensor of this embodiment are as follows:

[0048] 1) polydimethylsiloxane monomer and curing agent (1-hydroxycyclohexyl phenyl ketone, purchased from Dow Corning) were mixed in a mass ratio of 10:1, stirred at room temperature for 5 minutes to obtain a polydimethylsiloxane prepolymer solution, and allowed to stand for 20 minutes;

[0049] 2) Preparing a template using polyimide tape: Take a glass slide (75 mm × 25 mm × 2 mm), clean it with acetone, ethanol and deionized water, and then stick three polyimide tapes (~20 × 2 mm × 0.5 mm) on the glass slide. The three polyimide tapes form an unsealed equilateral triangle pattern on the glass slide to obtain a template with a linear concave pattern. In this embodiment, each polyimide tape is 10 mm long, 1 mm wide and 0.5 mm thick. The polyimide tape protrudes from the surface of the glass slide, and a linear concave pattern is formed between the edge of the tape and the glass slide.

[0050] 3) Apply the polydimethylsiloxane prepolymer liquid to the surface of the template obtained in step 2) (i.e., the surface of the glass slide and the three polyimide tapes), and heat it on a hot stage at 70°C for 2h. The polydimethylsiloxane prepolymer liquid forms a semi-solidified viscous base layer 1, and the thickness of the base layer 1 is 1mm; the base layer 1 forms a corresponding groove (with a depth of 0.5mm) at the concave part of the edge (long side) of the polyimide tape. In this embodiment, the equilateral triangle pattern formed by the three polyimide tapes forms three grooves on the surface of the base layer 1, and these three grooves are the three sides of the equilateral triangle pattern. The groove is consistent with the shape formed by the conductive lines 2-4 and the liquid metal electrodes 5-10.

[0051] 4) Before the substrate layer 1 is completely cured, a silver nanowire dispersion (a deionized water solution of silver nanowires) with a mass concentration of 10 mg / ml is brushed into the three grooves of the patterned substrate layer 1, and the silver nanowire dispersion is straightened with an art brush to arrange the silver nanowires in the same direction, and then placed on a hot stage at 70°C for 5 minutes to dry the silver nanowire dispersion and deposit the silver nanowires in the three grooves of the substrate layer 1. After the silver nanowire dispersion is dry, the process of brushing the silver nanowire dispersion is repeated 3 times, and finally three silver nanowire guide point lines with a width of 1 mm and a length of 10 mm are formed, as shown in FIG. Figure 1 As shown in 2-4.

[0052] 5) After the silver nanowire guide lines are dried, gallium-indium alloy is dripped onto the two ends of the silver nanowire guide lines in the three grooves of the substrate layer 1 to form liquid metal gallium-indium alloy electrodes 5-10 covering the two ends of the silver nanowire guide lines 2-4. The silver nanowire guide lines and the liquid metal gallium-indium alloy electrodes together form a sensing unit of the flexible omnidirectional sensor.

[0053] 6) Arrange a number of copper wires with a diameter of 0.15 mm in the liquid metal gallium-indium alloy 5-10 in the mold to form leads 12-17 for connecting external devices such as a voltmeter, an ammeter, a multimeter, and a resistance measurement module.

[0054] 7) A layer of polydimethylsiloxane prepolymer liquid is covered on the upper surface of the base layer 1 and the sensing unit, and heated at 70°C for 3 hours to completely solidify the polydimethylsiloxane prepolymer liquid to form an encapsulation layer 11 with a thickness of 1 mm. The product is then peeled off from the template to obtain a flexible strain sensor based on silver nanowires and liquid metal electrodes.

[0055] The schematic diagram of the sensor structure prepared in this embodiment is as follows Figure 1 As shown, A is a plan view of the sensor, and B is a cross-sectional view of the sensor; it can be seen that the sensor prepared in this embodiment includes a base layer 1 and an encapsulation layer 11, with a plurality of sensing units and leads arranged therebetween; the sensing unit is composed of silver nanowire guide lines 2-4, and liquid metal gallium indium alloy electrodes 5-10 covering the surface of each silver nanowire guide line; leads 12-17 for connecting external devices of the sensor are also arranged in the liquid metal gallium indium alloy.

[0056] The omnidirectional data detection results of the flexible omnidirectional strain sensor based on silver nanowires and gallium-indium alloy obtained in this embodiment are as follows: Figure 4-7 As shown. (The detection method reference: He F, You X, Gong H, et al. Stretchable, Biocompatible, and Multifunctional Silk Fibroin-Based Hydrogels toward Wearable Strain / Pressure Sensors and Triboelectric Nanogenerators [J]. ACS Appl Mater Interfaces, 2020, 12 (5): 6442-6450. The method disclosed in the literature). Figure 4-7 It can be seen that when the tensile strain is 2%, the resistance change GF at 0°, 30°, 60°, and 90° to the tensile direction are 22.8, 14.2, 5.7, and 3.6, respectively, showing a high degree of directional correlation.

[0057] In specific measurements, the information of stretching direction and strain magnitude can be obtained simultaneously by changing the resistance of the three branches 2, 3, and 4, that is, it has planar omnidirectional sensing. The omnidirectional sensing of the flexible omnidirectional strain sensor based on silver nanowires and liquid metal electrodes obtained in the embodiment is better than the flexible sensors in existing reports.

[0058] When strain ε is applied at an angle θ to the sensing line 2,

[0059]

[0060] In formulas (1)-(3), ΔR1, ΔR2, and ΔR3 are the resistance changes of the three sensing sensitive lines 2, 3, and 4, respectively; R1, R2, and R3 are the initial resistances of the three sensing sensitive lines 2, 3, and 4, respectively; and k is the coefficient of the relationship between strain and resistance change. Since the resistance change will change according to the applied strain and angle change, the resistance change of the three branches can be analyzed by the above three formulas, and the magnitude of the applied strain and the applied angle can be more accurately obtained.

[0061] Example 2

[0062] The sensor preparation method of this embodiment is as follows:

[0063] 1) mixing a polydimethylsiloxane monomer and a curing agent (1-hydroxycyclohexyl phenyl ketone) in a mass ratio of 10:1, stirring at room temperature for 5 minutes to obtain a polydimethylsiloxane prepolymer solution, and standing for 20 minutes;

[0064] 2) Preparing a template using polyimide tape: Take a glass slide 19 (75 mm×25 mm×2 mm), clean it with acetone, ethanol and deionized water in sequence, and set it aside;

[0065] Hollow dumbbell-shaped patterns are cut out on the surfaces of two polyimide tapes 18 (~20×2mm×0.5mm) and then pasted on a cleaned glass slide to obtain a template with two dumbbell-shaped concave patterns (20, 21). The two dumbbell-shaped patterns (20, 21) are at right angles to each other. Figure 3 As shown in A.

[0066] 3) The polydimethylsiloxane prepolymer liquid is applied to the surface of the template obtained in step 2) and heated on a hot stage at 70°C for 2 hours, so that the polydimethylsiloxane prepolymer liquid forms a semi-solidified viscous base layer with a thickness of 1 mm. Two grooves with a depth of 0.5 mm are formed at the base layer corresponding to the dumbbell-shaped pattern (20, 21).

[0067] 4) Before the base layer is completely solidified, apply a 10mg / ml silver nanowire (deionized water) dispersion to the grooves, and use an art pen to straighten the peaks and straighten the silver nanowire dispersion to make it in the same direction. Then place the template on a hot plate and heat it at 70°C for 3-5 minutes to dry the silver nanowire dispersion and deposit the silver nanowires at the bottom of the grooves. After the silver nanowire dispersion is dry, repeat the process 3 times to form a silver nanowire guide point line (2,3) with a width of 1mm and a length of 10mm;

[0068] 5) After the silver nanowire guide point lines (2, 3) are dried, gallium-indium alloy is dripped onto the two ends of the silver nanowire guide point lines in the groove of the substrate layer to form liquid metal gallium-indium alloy electrodes 5-8 covering the two ends of the silver nanowire guide point lines. The silver nanowire guide point lines and the liquid metal gallium-indium alloy electrodes together form a sensing unit of the flexible omnidirectional sensor.

[0069] 6) Arrange a number of copper wires with a diameter of 0.15 mm in the liquid metal gallium-indium alloy electrodes 5-8 in the mold to form leads 12-15 for connecting external devices such as a voltmeter, an ammeter, a multimeter, and a resistance measurement module.

[0070] 7) Cover the upper surface of the base layer and the sensing unit with a layer of polydimethylsiloxane prepolymer liquid, heat at 70°C for 3 hours, and wait for the polydimethylsiloxane prepolymer liquid to completely solidify to form an encapsulation layer 11 with a thickness of 1 mm. Then peel the product from the template to obtain a flexible strain sensor based on silver nanowires and liquid metal electrodes. The schematic diagram of the sensor structure obtained in this embodiment is shown in FIG. Figure 3 As shown in B.

[0071] The omnidirectional data of the flexible omnidirectional strain sensor based on silver nanowires and liquid metal electrodes obtained in this embodiment (the detection method is the same as that in Embodiment 1) are shown in Table 1 below.

[0072] Table 1 Omnidirectional data detection results of the sensor in Example 2

[0073] 0° 30° 60° 90° strain(%) 1％ 1％ 1％ 1％ GF 20.8 13.5 7.9 2.4

[0074] The test results in Table 1 show that the sensor prepared in this example exhibits a high degree of directional correlation and obtains the same performance as that of Example 1.

[0075] Example 3

[0076] The sensor preparation method of this embodiment is the same as that of embodiment 2, and the difference from embodiment 2 is that the silver nanowire guide line length prepared in this embodiment is 5 mm and the width is 0.5 mm. The omnidirectional data of the flexible omnidirectional strain sensor based on silver nanowires and liquid metal electrodes obtained in this embodiment (the detection method is the same as that of embodiment 1) are shown in Table 2 below.

[0077] Table 2 Omnidirectional data detection results of the sensor in Example 3

[0078] 0° 30° 60° 90° strain(%) 1％ 1％ 1％ 1％ GF 28.3 19.7 10.5 4.7

[0079] The test results in Table 2 show that the sensor prepared in this example exhibits a high degree of directional correlation and obtains the same performance as that of Example 1.

[0080] The 1000 cycles of the flexible omnidirectional sensor of the silver nanowire and liquid metal electrode obtained in this embodiment under 1% strain are as follows: Figure 8 As shown, it can be seen that the sensor has good stability.

[0081] Example 4

[0082] The sensor preparation method of this embodiment is the same as that of Embodiment 3, but different from that of Embodiment 3 in that: the silver nanowire conductive lines of this embodiment are prepared by scraping.

[0083] The omnidirectional data of the flexible omnidirectional strain sensor based on silver nanowires and liquid metal electrodes obtained in this embodiment (the detection method is the same as that in Embodiment 1) are shown in Table 3 below.

[0084] Table 3 Omnidirectional data detection results of the sensor in Example 4

[0085] 0° 30° 60° 90° strain(%) 1％ 1％ 1％ 1％ GF 17.4 11.6 7.5 3.9

[0086] The test results in Table 3 show that the sensor prepared in this example exhibits a high degree of directional correlation and obtains the same performance as that of Example 1.

[0087] Example 5

[0088] The sensor preparation method of this embodiment is the same as that of Embodiment 2, but different from that of Embodiment 2 in that the groove depth of the polydimethylsiloxane-based bottom layer prepared in this embodiment is 0.1 mm.

[0089] The omnidirectional data of the flexible omnidirectional strain sensor based on silver nanowires and liquid metal electrodes obtained in this example (the detection method is the same as that in Example 1) are shown in Table 4 below.

[0090] Table 4 Omnidirectional data detection results of the sensor in Example 5

[0091] 0° 30° 60° 90° strain(%) 1％ 1％ 1％ 1％ GF 23.2 16.9 11.5 5.4

[0092] The test results in Table 4 show that the sensor prepared in this example exhibits a high degree of directional correlation and obtains the same performance as that of Example 1.

[0093] Example 6

[0094] The sensor preparation method of this embodiment is the same as that of Embodiment 1, but different from Embodiment 1 in that the thickness of the base layer 1 and the packaging layer 11 prepared in this embodiment are both 2 mm.

[0095] The omnidirectional data of the flexible omnidirectional strain sensor based on silver nanowires and liquid metal electrodes obtained in this example (the detection method is the same as that in Example 1) are shown in Table 5 below.

[0096] Table 5 Omnidirectional data detection results of the sensor in Example 6

[0097] 0° 30° 60° 90° strain(%) 1％ 1％ 1％ 1％ GF 16.9 12.1 8.3 2.7

[0098] The test results in Table 5 show that the sensor prepared in this example exhibits a high degree of directional correlation and obtains the same performance as that of Example 1.

[0099] Example 7

[0100] The sensor preparation method of this embodiment is the same as that of Embodiment 1, but different from Embodiment 1 in that this embodiment uses an aluminum wire with a diameter of 0.05 mm as a connecting lead.

[0101] The omnidirectional data of the flexible omnidirectional strain sensor based on silver nanowires and liquid metal electrodes obtained in this example (the detection method is the same as that in Example 1) are shown in Table 6 below.

[0102] Table 6 Omnidirectional data detection results of the sensor in Example 7

[0103] 0° 30° 60° 90° strain(%) 1％ 1％ 1％ 1％ GF 21.5 15.5 7.8 3.6

[0104] The test results in Table 6 show that the sensor prepared in this example exhibits a high degree of directional correlation and obtains the same performance as that of Example 1.

[0105] The above examples illustrate that the sensor prepared by the method of the present application exhibits a high degree of directional correlation and high repeatability and can be implemented stably.

Claims

1. A flexible omnidirectional sensor based on silver nanowires and liquid metal electrodes, characterized in that: The sensor comprises a base layer and an encapsulation layer, with a plurality of sensing units and leads arranged between the base layer and the encapsulation layer; The sensing unit is composed of a silver nanowire guide line and a liquid metal gallium indium alloy electrode covering both ends of the silver nanowire guide line, and the liquid metal gallium indium alloy electrode is also provided with a plurality of leads leading to the outside of the sensor; The base layer and the encapsulation layer are both obtained by curing a polydimethylsiloxane prepolymer solution; the polydimethylsiloxane prepolymer solution is obtained by mixing a polydimethylsiloxane monomer and a curing agent.

2. The flexible omnidirectional sensor based on silver nanowires and liquid metal electrodes according to claim 1, characterized in that: The silver nanowire guide point line has a width of 0.5-1 mm and a length of 5-10 mm.

3. The flexible omnidirectional sensor based on silver nanowires and liquid metal electrodes according to claim 1, characterized in that: The silver nanowire guide point lines are obtained by depositing a silver nanowire dispersion.

4. The flexible omnidirectional sensor based on silver nanowires and liquid metal electrodes according to claim 1, characterized in that: The thickness of the base layer is 0.5-1 mm, and the thickness of the encapsulation layer is 0.5-1 mm.

5. The method for preparing a flexible omnidirectional sensor based on silver nanowires and liquid metal electrodes according to any one of claims 1 to 4, characterized in that: The specific steps are as follows: 1) Mixing polydimethylsiloxane monomer and curing agent to obtain polydimethylsiloxane prepolymer solution for standby use; 2) Prepare a template with a concave pattern on the surface of a glass slide using polyimide tape; 3) The polydimethylsiloxane prepolymer liquid is evenly coated on the surface of the template and heated, so that the polydimethylsiloxane prepolymer liquid forms a base layer, and the base layer forms a groove at the pattern of the template; 4) Apply the silver nanowire dispersion to the grooves of the substrate layer, and arrange the nanowires in the same direction, heat, and after the silver nanowire dispersion is dried, repeat the above process 3-5 times to obtain silver nanowire guide point lines; 5) dripping liquid metal gallium indium alloy onto both ends of the silver nanowire guide line in the groove to form a liquid metal gallium indium alloy electrode; arranging a number of lead wires in the liquid metal gallium indium alloy electrode; 6) uniformly covering the substrate layer and the electrode surface with a layer of polydimethylsiloxane prepolymer prepared in step 1), and curing the polydimethylsiloxane prepolymer after heating to form an encapsulation layer; peeling the product from the template surface to obtain the flexible omnidirectional sensor based on silver nanowires and liquid metal electrodes.

6. The method according to claim 5, characterized in that Step 1) The mass ratio of the polydimethylsiloxane monomer to the curing agent is 10:

1.

7. The method according to claim 5, characterized in that Step 1) The curing agent is 1-hydroxycyclohexyl phenyl ketone.

8. The method according to claim 5, characterized in that Step 3) The groove has a depth of 0.1-0.5 mm.

9. The method according to claim 5, characterized in that Step 4) The silver nanowire dispersion refers to a silver nanowire deionized water dispersion with a mass concentration of 10 mg / ml.

10. The method according to claim 5, characterized in that Step 4) The silver nanowire guide line has a width of 0.5-1 mm and a length of 5-10 mm.

Images