A piezoresistive sensor based on locust bean gum hydrogel and its preparation method and application

Abstract

The present invention provides a piezoresistive sensor based on locust bean gum hydrogel, and its preparation method and application. The piezoresistive sensor of the present invention comprises: an electrode and a piezoresistive material, wherein the electrode and the piezoresistive material form a sandwich structure of an electrode, a piezoresistive material, and an electrode; the piezoresistive material is a locust bean gum hydrogel; the electrode is a carbon cloth electrode; the roughness (Ra) of the contact surface between the piezoresistive material and the electrode is 30 to 60 μm. The piezoresistive sensor based on locust bean gum hydrogel of the present invention is simple to prepare, wherein the piezoresistive material based on natural polymer has electronic conductivity and good elasticity, and the piezoresistive sensor has high sensitivity, and the sensitivity within 0-10 KPa can reach 20.5 KPa. ‑1 .

Description

Technical Field

[0001] The present invention belongs to the technical field of piezoresistive sensors, and more specifically, to a piezoresistive sensor based on locust bean gum hydrogel, and a preparation method and application thereof. Background Art

[0002] Hydrogel is a type of polymer with a three-dimensional network structure formed by polymer materials. It contains a large amount of water inside and has adjustable mechanical, thermodynamic and ion / electron transport properties. It has great application potential in sensors. There are many kinds of raw materials for preparing hydrogels. You can use polymer monomer materials, polymer polymer materials (divided into natural polymers and synthetic polymers) or a mixture of polymer monomers and polymers. Among them, natural polymers such as gelatin, cellulose, chitosan, sodium alginate or silk are abundant in nature and have good biocompatibility. They can be used to prepare hydrogels. Hydrogels based on natural polymers have the characteristics of high safety, high biocompatibility, low cost and adjustable electrical and mechanical properties. In recent years, they have been widely used in various flexible wearable devices such as flexible piezoresistive sensors.

[0003] The Chinese patent "A composite graphene aerogel, its preparation and application in supercapacitive pressure sensor" discloses a composite graphene aerogel composed of regenerated silk protein and graphene material, which can be used in piezoresistive sensors. However, the piezoresistive sensor based on the composite graphene aerogel has a sensitivity of 0.73KPa at 0.01-10KPa. -1 , the sensitivity is low. And the preparation process of the composite graphene aerogel is complicated.

[0004] Therefore, it is of great significance to develop a piezoresistive sensor based on natural polymer hydrogel with high sensitivity and simple hydrogel preparation process. Summary of the Invention

[0005] The present invention aims to address the low sensitivity and complex preparation process of current natural polymer piezoresistive sensors by providing a piezoresistive sensor based on locust bean gum hydrogel. The piezoresistive sensor based on locust bean gum hydrogel has high sensitivity, with a sensitivity of up to 20.5 kPa within the range of 0-10 kPa. -1 Among them, the piezoresistive materials based on natural polymers are simple to prepare, have electronic conductivity and good elasticity.

[0006] Another object of the present invention is to provide a method for preparing a piezoresistive sensor based on locust bean gum hydrogel.

[0007] Another object of the present invention is to provide an application of a piezoresistive sensor based on locust bean gum hydrogel.

[0008] The above-mentioned purpose of the present invention is achieved through the following technical solutions:

[0009] A piezoresistive sensor based on locust bean gum hydrogel, comprising a first electrode, a piezoresistive material and a second electrode stacked in sequence;

[0010] The piezoresistive material is locust bean gum hydrogel; the first electrode and the second electrode are both carbon cloth electrodes;

[0011] The roughness (Ra) of the contact surface between the piezoresistive material and the electrode is 30-60 μm.

[0012] Locust bean gum is a natural galactomannan extracted from the seeds of the locust tree. It has strong salt tolerance, strong water absorption, high stability and low cost.

[0013] Researchers have discovered that by introducing water-soluble polymers into an aqueous medium with locust bean gum as the main component, forming a cross-linked network based on chemical or physical interactions, and adding a conductive agent, a hydrogel with both electronic conductivity and good mechanical elasticity can be formed. The inventors discovered that piezoresistive sensors fabricated by layering a first electrode, the hydrogel, and a second electrode exhibited low sensitivity, affecting the device's detection accuracy.

[0014] After multiple experiments, the inventors of the present invention found that the contact area between the first electrode, the second electrode and the locust bean gum hydrogel has a significant impact on the sensitivity. By selecting carbon cloth as the first electrode and the second electrode and simultaneously adjusting the roughness of the locust bean gum hydrogel surface (the surface in contact with the first electrode and the second electrode), the contact points between the locust bean gum hydrogel surface and the first electrode and the second electrode are increased, causing a change in the contact resistance value, thereby improving the sensitivity of the locust bean gum hydrogel piezoresistive sensor.

[0015] The present invention uses carbon cloth as an electrode and locust bean gum hydrogel with a specific roughness as a piezoresistive material to assemble a piezoresistive sensor. The electrode and the piezoresistive material form a sandwich structure of electrode, piezoresistive material, and electrode, which greatly improves the change in contact resistance caused by the change in the contact point between the hydrogel surface and the conductive electrode, thereby greatly improving the sensitivity of the sensor. The piezoresistive sensor based on locust bean gum hydrogel of the present invention is simple to prepare. The piezoresistive material based on natural polymers has electronic conductivity and good elasticity. The piezoresistive sensor has high sensitivity and can reach a sensitivity of 20.5KPa within 0-10KPa. -1 .

[0016] If other electrode materials are used as the first and second electrodes, it will be difficult to ensure sufficient contact between the locust bean gum hydrogel surface and the first and second electrodes, thereby reducing the sensitivity of the locust bean gum hydrogel piezoresistive sensor. If the roughness of the contact surface between the piezoresistive material and the electrodes is too small, there will be too few contact points between the hydrogel surface and the conductive electrode, and the sensor current will not change much when pressure is applied, thereby reducing the sensitivity of the locust bean gum hydrogel piezoresistive sensor. If the contact surface roughness is too large, it will be difficult for the hydrogel surface to make good contact with the conductive electrode, thereby reducing the sensitivity of the locust bean gum hydrogel piezoresistive sensor.

[0017] The locust bean gum hydrogel in the piezoresistive material of the piezoresistive sensor of the present invention can be one piece or multiple pieces, so that the roughness of the contact surface between the piezoresistive material and the first electrode and the second electrode is 30 to 60 μm.

[0018] Preferably, the roughness Ra of the contact surface between the piezoresistive material and the electrode is 43-51 μm.

[0019] Preferably, the locust bean gum hydrogel at least includes a first locust bean gum hydrogel stacked with the first electrode and a second locust bean gum hydrogel stacked with the second electrode, and the first locust bean gum hydrogel and the second locust bean gum hydrogel are stacked.

[0020] More preferably, the locust bean gum hydrogel includes a first locust bean gum hydrogel stacked with the first electrode, and a second locust bean gum hydrogel stacked with the second electrode; one side of the first locust bean gum hydrogel and the second locust bean gum hydrogel are both rough surfaces, and the other side is both flat surfaces, the roughness of the flat surface is 0 to 30 μm; the roughness of the rough surface is 30 to 60 μm.

[0021] Further preferably, the roughness of the flat surfaces of the first locust bean gum hydrogel and the second locust bean gum hydrogel is 9-12 μm.

[0022] Preferably, the thickness of the piezoresistive material is 0.3-0.5 cm.

[0023] The method for preparing the above-mentioned piezoresistive sensor comprises the following steps:

[0024] Assembling the first electrode, the piezoresistive material and the second electrode layer by layer to obtain the piezoresistive sensor;

[0025] The piezoresistive material is locust bean gum hydrogel; the first electrode and the second electrode are both carbon cloth electrodes.

[0026] Preferably, the piezoresistive material is prepared by the following process:

[0027] S1: uniformly mixing a water-soluble polymer, a conductive agent, and water, and adding locust bean gum to obtain a mixed solution; placing the mixed solution in a flat container and freezing it to obtain a first locust bean gum hydrogel having a rough surface and a flat surface;

[0028] S2: uniformly mixing a water-soluble polymer, a conductive agent, and water, and adding locust bean gum to obtain a mixed solution; placing the mixed solution in a flat container and freezing it to obtain a second locust bean gum hydrogel having a rough surface and a flat surface;

[0029] S3: Laminating the flat surfaces of the first locust bean gum hydrogel and the second locust bean gum hydrogel to obtain the piezoresistive material;

[0030] The roughness of a certain surface of the flat container in S1 that contacts the mixed solution (such as the side wall or the bottom surface, ie, the contact surface forming the flat surface of the hydrogel) is independently 0 to 30 μm.

[0031] The roughness of a certain surface of the flat container in S2 that contacts the mixed solution (such as the side wall or the bottom surface, ie, the contact surface forming the flat surface of the hydrogel) is independently 0 to 30 μm.

[0032] Preferably, the roughness of a certain surface of the flat container in S1 that contacts the mixed solution (such as the side wall or bottom surface, ie, the contact surface forming the flat surface of the hydrogel) is 9-12 μm.

[0033] Preferably, the roughness of a certain surface of the flat container in S2 that contacts the mixed solution (such as the side wall or bottom surface, ie, the contact surface forming the flat surface of the hydrogel) is 9-12 μm.

[0034] Preferably, the mass ratio of the locust bean gum to the water-soluble polymer in S1 is independently 1:(2-8).

[0035] The mass ratio of the locust bean gum to the conductive agent in S1 is independently 1:(0.15-0.3).

[0036] The mass ratio of locust bean gum to water in S1 is independently 1:(20-45).

[0037] Preferably, the mass ratio of the locust bean gum to the water-soluble polymer in S2 is independently 1:(2-8).

[0038] The mass ratio of the locust bean gum to the conductive agent in S2 is independently 1:(0.15-0.3).

[0039] The mass ratio of locust bean gum to water in S2 is independently 1:(20-45).

[0040] Conventional water-soluble polymers and conductive agents in this field can be used in the present invention.

[0041] Preferably, the water-soluble polymer in S1 is independently selected from one or more of polyvinyl alcohol, polyethylene glycol, polyvinyl pyrrolidone, polyacrylic acid, polyacrylamide, polyacrylate, chitosan, carboxymethyl cellulose salt, carboxymethyl cellulose, alginate, and methyl cellulose.

[0042] The conductive agent in S1 is independently selected from one or more of carbon nanotubes, conductive carbon black particles, acetylene black, carbon fibers, conductive graphite sheets, and graphene.

[0043] Preferably, the water-soluble polymer in S2 is independently selected from one or more of polyvinyl alcohol, polyethylene glycol, polyvinyl pyrrolidone, polyacrylic acid, polyacrylamide, polyacrylate, chitosan, carboxymethyl cellulose salt, carboxymethyl cellulose, alginate, and methyl cellulose.

[0044] The conductive agent in S2 is independently selected from one or more of carbon nanotubes, conductive carbon black particles, acetylene black, carbon fibers, conductive graphite sheets, and graphene.

[0045] Preferably, the uniform mixing process in S1 is: dissolving and uniformly mixing the water-soluble polymer, the conductive agent and water, and the temperature is independently 90-100°C.

[0046] Preferably, the uniform mixing process in S2 is: dissolving the water-soluble polymer, the conductive agent and water and uniformly mixing them, and the temperature is independently 90-100°C.

[0047] Preferably, the freezing temperature in S1 is independently -20 to -30°C, and the freezing time is independently 12 to 18 hours.

[0048] Preferably, the freezing temperature in S2 is independently -20 to -30°C, and the freezing time is independently 12 to 18 hours.

[0049] Application of the above-mentioned locust bean gum hydrogel-based piezoresistive sensor in the preparation of flexible piezoresistive sensors.

[0050] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0051] The present invention uses a locust bean gum hydrogel with rough upper and lower surfaces as a piezoresistive material, which is combined with a carbon cloth electrode to form a sandwich structure of electrode, piezoresistive material, and electrode. This increases the contact points between the locust bean gum hydrogel and the carbon cloth electrode, thereby significantly improving the sensitivity of the sensor. The piezoresistive sensor based on the locust bean gum hydrogel of the present invention is simple to prepare. The piezoresistive material based on the natural polymer has electronic conductivity and good elasticity. The piezoresistive sensor has high sensitivity, with a sensitivity of up to 20.5 kPa within the range of 0-10 kPa. -1 . BRIEF DESCRIPTION OF THE DRAWINGS

[0052] Figure 1 This is a scanning electron micrograph of the upper surface of locust bean gum hydrogel.

[0053] Figure 2 This is a scanning electron micrograph of the lower surface of locust bean gum hydrogel.

[0054] Figure 3 Schematic diagram of the structure of the piezoresistive sensor of Example 4.

[0055] Figure 4 These are the elasticity test diagrams of locust bean gum hydrogel, (a) is a photo of the hydrogel before compression; (b) is a photo of the hydrogel when compressed; (c) is a photo of the hydrogel after recovery after the pressure is withdrawn. DETAILED DESCRIPTION

[0056] The technical solutions in the examples of the present invention are described below in a clear and complete manner, but the embodiments of the present invention are not limited thereto. The raw materials in the examples can be obtained commercially; unless otherwise specified, the reagents, methods, and equipment used in the present invention are conventional reagents, methods, and equipment in the art.

[0057] Sensitivity (S) is one of the important parameters for evaluating sensor performance. The present invention uses the following test method to test the sensitivity of the piezoresistive sensors obtained in the examples and comparative examples. The specific process is: applying current and voltage across the sensor, using an ammeter to test the electrical performance of the device, recording the change in the applied pressure and current over time, and calculating the sensitivity of the piezoresistive sensor using the following formula:

[0058]

[0059] Where ΔP is the change in applied pressure, I0 is the current value when there is no pressure, and ΔI / I0 is the rate of change of current.

[0060] Example 1

[0061] A method for preparing a piezoresistive material comprises the following steps:

[0062] S1. 4 g of polyvinyl alcohol, 0.3 g of carbon nanotubes, and 40 g of water were mixed and heated at 100°C until the polyvinyl alcohol was completely dissolved. 1 g of locust bean gum was added to the solution and stirred until the locust bean gum was completely dissolved. The resulting solution was poured into a petri dish and frozen at -20°C for 12 hours to obtain a first locust bean gum hydrogel.

[0063] S2. The hydrogel obtained in S1 was peeled off from the culture dish 1. The obtained hydrogel had a flat surface and a rough surface. The roughness of the flat surface was 9.2 μm, and the roughness of the rough surface was 45.6 μm.

[0064] A second locust bean gum hydrogel was prepared according to the same preparation method. The roughness of the flat surface of the obtained hydrogel was 10.3 μm, and the roughness of the rough surface was 50.2 μm.

[0065] Example 2

[0066] A method for preparing a piezoresistive material comprises the following steps:

[0067] S1. 4 g of polyvinyl alcohol, 0.3 g of carbon nanotubes, and 40 g of water were mixed and heated at 100°C until the polyvinyl alcohol was completely dissolved. 1 g of locust bean gum was added to the solution and stirred until the locust bean gum was completely dissolved. The resulting solution was poured into a petri dish and frozen at -20°C for 12 hours to obtain a first locust bean gum hydrogel.

[0068] S2. The hydrogel obtained in S1 was peeled off from the culture dish. The obtained hydrogel had a flat surface and a rough surface. The roughness of the flat surface was 10.5 μm, and the roughness of the rough surface was 49.5 μm.

[0069] A second locust bean gum hydrogel was prepared according to the same preparation method. The roughness of the flat surface of the obtained hydrogel was 9.8 μm, and the roughness of the rough surface was 43.2 μm.

[0070] Example 3

[0071] A method for preparing a piezoresistive sensor based on locust bean gum hydrogel comprises the following steps:

[0072] S1. The first carbon cloth electrode, the first locust bean gum hydrogel obtained in Example 1, and the flat surfaces of the second locust bean gum hydrogel are bonded together to form a piezoresistive material with rough upper and lower surfaces and the second carbon cloth electrode, and the locust bean gum hydrogel piezoresistive sensor is obtained by assembling the material and the second carbon cloth electrode layer by layer.

[0073] The sensitivity of the obtained sensor in the range of 0-10 kPa is 20.5 kPa -1 .

[0074] Example 4

[0075] A method for preparing a piezoresistive sensor based on locust bean gum hydrogel comprises the following steps:

[0076] S1. The first carbon cloth electrode, the first locust bean gum hydrogel obtained in Example 2, and the flat surfaces of the second locust bean gum hydrogel are bonded together to form a piezoresistive material with rough upper and lower surfaces and the second carbon cloth electrode, and the locust bean gum hydrogel piezoresistive sensor is obtained by assembling the material and the second carbon cloth electrode layer by layer.

[0077] The sensitivity of the obtained sensor in the range of 0-10 kPa is 19.8 kPa -1 .

[0078] Comparative Example 1

[0079] A method for preparing a locust bean gum hydrogel piezoresistive sensor comprises the following steps:

[0080] S1. Assemble the first carbon cloth electrode, the first locust bean gum hydrogel obtained in Example 1 as a piezoresistive material, and the second carbon cloth electrode layer by layer to obtain a locust bean gum hydrogel piezoresistive sensor.

[0081] The sensitivity of the obtained sensor in the range of 0-10 kPa is 1.45 kPa -1 .

[0082] Comparative Example 2

[0083] A method for preparing a piezoresistive sensor of locust bean gum hydrogel comprises the following steps:

[0084] S1. The first copper foil electrode, the first locust bean gum hydrogel obtained in Example 1, and the flat surfaces of the second locust bean gum hydrogel are bonded together to form a piezoresistive material with rough upper and lower surfaces and the second copper foil electrode, and the locust bean gum hydrogel piezoresistive sensor is obtained by assembling the material and the second copper foil electrode layer by layer.

[0085] The sensitivity of the obtained sensor in the range of 0-10 kPa is 0.55 kPa -1 .

[0086] Comparative Example 3

[0087] A method for preparing a piezoresistive sensor of locust bean gum hydrogel comprises the following steps:

[0088] S1. The first carbon cloth electrode, the first locust bean gum hydrogel obtained in Example 1, and the rough surface of the second locust bean gum hydrogel are bonded together to form a piezoresistive material with smooth upper and lower surfaces, and the second carbon cloth electrode are assembled layer by layer to obtain a locust bean gum hydrogel piezoresistive sensor.

[0089] The sensitivity of the obtained sensor in the range of 0-10 kPa is 0.022 kPa -1 .

[0090] Figure 1 This is a scanning electron microscope image of the upper surface of the first locust bean gum hydrogel in Example 1. Figure 2 The scanning electron microscope image of the lower surface shows that the upper surface of the locust bean gum hydrogel prepared by the present invention is relatively rough (roughness is 45.6 μm), while the lower surface in contact with the culture dish surface is relatively flat (roughness is 9.2 μm). The specific surface area of ​​the rough surface is much larger than that of the flat surface, which is conducive to contact with the carbon cloth electrode.

[0091] Figure 3This is a structural schematic diagram of a piezoresistive sensor based on locust bean gum hydrogel in Example 3 of the present application, where 1 and 4 are carbon cloth electrodes, 2 and 3 are locust bean gum hydrogels, and the flat surfaces of the two hydrogels are bonded together to form a piezoresistive material with rough upper and lower surfaces. By using carbon cloth with a higher surface roughness as the sensor electrode, the change in contact resistance value caused by the change in the contact point between the hydrogel surface and the conductive electrode is greatly improved, thereby greatly improving the sensitivity of the piezoresistive sensor.

[0092] Figure 4 Figures 2 and 3 show the elasticity test of the first locust bean gum hydrogel obtained in Example 1. (a) shows the hydrogel before compression; (b) shows the hydrogel under compression; and (c) shows the hydrogel after recovery after the pressure is removed. The figures show that the hydrogel has good elasticity.

[0093] As can be seen from Examples 1 to 4, the present application assembles a piezoresistive sensor by selecting carbon cloth as the electrode and locust bean gum hydrogel with a specific roughness as the piezoresistive material. The electrode and the piezoresistive material form a sandwich structure of electrode, piezoresistive material, and electrode, which greatly improves the change in contact resistance caused by the change in the contact point between the hydrogel surface and the conductive electrode, thereby greatly improving the sensitivity of the sensor. The sensitivity of the piezoresistive sensor prepared in Example 3 is 20.5KPa within 0-10KPa. -1 The sensitivity of the piezoresistive sensor prepared in Example 4 within the range of 0-10 KPa is 19.8 KPa. -1 .

[0094] Compared with the examples, in Comparative Example 1, only the first locust bean gum hydrogel prepared in Example 1 was used as the piezoresistive material, and carbon cloth was used as the electrode to assemble a sandwich-structured locust bean gum hydrogel piezoresistive sensor. Since the roughness of the flat surface did not reach 30-60 μm, the contact points between the hydrogel surface and the conductive electrode were reduced, and the sensor current did not change much when pressure was applied, resulting in the sensitivity of the obtained sensor being only 1.45 kPa within 0-10 kPa. -1 In Comparative Example 2, the carbon cloth electrode was replaced with a copper foil electrode, which also reduced the contact points between the hydrogel surface and the conductive electrode. The sensitivity of the resulting sensor in the range of 0-10 kPa was only 0.55 kPa. -1 Comparative Example 3: The first locust bean gum hydrogel prepared in Example 1 was bonded to the rough surface of the second locust bean gum hydrogel to form a hydrogel with smooth upper and lower surfaces as a piezoresistive material. A piezoresistive sensor was assembled using carbon cloth as an electrode, which greatly reduced the contact points between the hydrogel surface and the conductive electrode. The sensitivity of the resulting sensor within 0-10 kPa was only 0.022 kPa. -1 .

[0095] The above embodiments of the present invention are merely examples for the purpose of clearly illustrating the present invention and are not intended to limit the embodiments of the present invention. Those skilled in the art will appreciate that other variations or modifications may be made based on the above. It is not necessary and impossible to enumerate all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention are intended to be included within the scope of protection of the claims of the present invention.

Claims

1. A piezoresistive sensor based on locust bean gum hydrogel, characterized in that: It includes a first electrode, a piezoresistive material and a second electrode stacked in sequence; The piezoresistive material is locust bean gum hydrogel; the first electrode and the second electrode are both carbon cloth electrodes; The roughness Ra of the contact surface between the piezoresistive material and the electrode is 30-60 μm; The piezoresistive material is prepared by the following process: S1: uniformly mixing a water-soluble polymer, a conductive agent, and water, and adding locust bean gum to obtain a mixed solution; placing the mixed solution in a flat container and freezing it to obtain a first locust bean gum hydrogel having a rough surface and a flat surface, which is set aside; S2: uniformly mixing a water-soluble polymer, a conductive agent, and water, and adding locust bean gum to obtain a mixed solution; placing the mixed solution in a flat container and freezing it to obtain a second locust bean gum hydrogel having a rough surface and a flat surface, which is set aside; S3: Laminating the flat surfaces of the first locust bean gum hydrogel and the second locust bean gum hydrogel to obtain the piezoresistive material; The roughness of one of the surfaces of the flat container in S1 and S2 that contacts the mixed solution is independently 0 to 30 μm.

2. The piezoresistive sensor according to claim 1, characterized in that: The roughness Ra of the contact surface between the piezoresistive material and the electrode is 43-51 μm.

3. The piezoresistive sensor according to claim 1, wherein: The locust bean gum hydrogel at least includes a first locust bean gum hydrogel stacked with the first electrode and a second locust bean gum hydrogel stacked with the second electrode, and the first locust bean gum hydrogel and the second locust bean gum hydrogel are stacked.

4. The piezoresistive sensor according to claim 1, characterized in that: The thickness of the piezoresistive material is 0.3-0.5 cm.

5. The method for preparing a piezoresistive sensor according to any one of claims 1 to 4, characterized in that: The method comprises the following steps: assembling the first electrode, the piezoresistive material and the second electrode layer by layer to obtain the piezoresistive sensor.

6. The preparation method according to claim 5, characterized in that: The piezoresistive material is prepared by the following process: S1: uniformly mixing a water-soluble polymer, a conductive agent, and water, and adding locust bean gum to obtain a mixed solution; placing the mixed solution in a flat container and freezing it to obtain a first locust bean gum hydrogel having a rough surface and a flat surface, which is set aside; S2: uniformly mixing a water-soluble polymer, a conductive agent, and water, and adding locust bean gum to obtain a mixed solution; placing the mixed solution in a flat container and freezing it to obtain a second locust bean gum hydrogel having a rough surface and a flat surface, which is set aside; S3: Laminating the flat surfaces of the first locust bean gum hydrogel and the second locust bean gum hydrogel to obtain the piezoresistive material; The roughness of one of the surfaces of the flat container in S1 and S2 that contacts the mixed solution is independently 0 to 30 μm.

7. The preparation method according to claim 6, characterized in that: The mass ratio of locust bean gum to water-soluble polymer in S1 and S2 is independently 1:(2~8); the mass ratio of locust bean gum to conductive agent in S1 and S2 is independently 1:(0.15~0.3); the mass ratio of locust bean gum to water in S1 and S2 is independently 1:(20~45).

8. The preparation method according to claim 6, characterized in that: The uniform mixing process in S1 and S2 is: dissolving the water-soluble polymer, the conductive agent and water and uniformly mixing them, and the temperature is independently 90-100°C.

9. The preparation method according to claim 6, characterized in that: The freezing temperature in S1 and S2 is independently -20 to -30°C, and the freezing time is independently 12 to 18 hours.

10. Use of the piezoresistive sensor according to any one of claims 1 to 4 in the preparation of a flexible piezoresistive sensor.

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