A flexible pressure sensor with a variable modulus structure and a method for manufacturing the same

Abstract

The present invention relates to a flexible pressure sensor with a variable modulus structure and a preparation method thereof, belonging to the technical field of pressure sensor preparation. The flexible pressure sensor disclosed in the present invention comprises a flexible packaging layer, a sensitive unit layer and an electrode layer, wherein the sensitive unit layer is located above the electrode layer, and the flexible packaging layer wraps the sensitive unit layer and the electrode layer. In the flexible pressure sensor of the present invention, materials with different pore sizes are used to form material layers with different pore sizes and different thicknesses in a mold, and after melting the materials with different pore sizes in warm water, a stepped mesh structure is obtained, which is then immersed in a conductive solution to form a sensitive unit layer. The preparation cost is low, the process is simple, and the flexible pressure sensor can be widely used in the market and put into use in intelligent robots, health monitoring, human-computer interaction, intelligent medical equipment, intelligent wearable systems, etc. The flexible pressure sensor has great application prospects in the adaptable field.

Description

Technical Field

[0001] The present invention belongs to the technical field of pressure sensor preparation, and relates to a flexible pressure sensor with a variable modulus structure and a preparation method thereof. Background Art

[0002] In recent years, with the rise of wearable smart devices and the innovation and development of intelligent medical equipment, the development of flexible pressure sensors has been greatly promoted, stimulating a huge demand for detection devices that convert mechanical signals into electrical signals.

[0003] Traditional flexible pressure sensors have problems such as low sensitivity, small stress response range and poor linearity, while current flexible pressure sensors based on new materials have problems such as complex preparation methods and expensive materials. Both of these limit the practical application of traditional flexible pressure sensors.

[0004] Therefore, in-depth research on flexible pressure sensors with a wide response range, high sensitivity and good linearity is crucial for many application fields such as wearable devices and intelligent medical devices.

[0005] Therefore, in order to overcome the problem that the three parameters of flexible pressure sensors, namely sensitivity, stress response range and linearity, cannot be taken into account at the same time, the flexible pressure sensor is realized to have the characteristics of high sensitivity and good linearity in a wide stress response range, and also has the characteristics of reducing preparation material costs, reducing preparation difficulty and avoiding environmental pollution. It is necessary to conduct in-depth research on a flexible pressure sensor based on a variable modulus structure and the corresponding preparation method, so as to be able to design the pore diameter, pore layer thickness and number of stepped pore layers of the stepped mesh structure according to actual application requirements, and obtain a flexible pressure sensor with a wide response range, high sensitivity and good linearity, which is crucial for many application fields such as wearable devices and intelligent medical equipment. Summary of the Invention

[0006] In view of this, one of the objects of the present invention is to provide a flexible pressure sensor with a variable modulus structure; a second object of the present invention is to provide a method for preparing a flexible pressure sensor with a variable modulus structure.

[0007] In order to achieve the above object, the present invention provides the following technical solutions:

[0008] 1. A flexible pressure sensor with a variable modulus structure, comprising a flexible packaging layer, a sensitive unit layer, and an electrode layer, wherein the sensitive unit layer is located above the electrode layer, and the flexible packaging layer wraps the sensitive unit layer and the electrode layer;

[0009] The material of the flexible packaging layer is piezoresistive tape or plastic film with a thickness of 1 μm to 500 μm;

[0010] The electrode layer is an interdigitated electrode or a parallel plate electrode, and the electrode material in the electrode layer is any one of aluminum foil, silver foil or copper foil;

[0011] The thickness of the sensitive unit layer is 1 mm to 500 mm and is prepared according to the following method: (1) materials with different pore sizes are mixed with a high molecular polymer solution respectively, and stirred to mix them uniformly to obtain mixed solutions with different pore sizes;

[0012] (2) transferring the mixed solutions of different pore sizes into the mold in sequence. The order of transferring the mixed solutions of different pore sizes can be arbitrarily combined to form material layers of different pore sizes and different thicknesses;

[0013] (3) placing the mold in a vacuum drying oven and curing it, then taking it out to obtain a mixed solid;

[0014] (4) immersing the mixed solid in a solvent to melt the materials with different pore sizes in the mixed solid, and vacuum drying to obtain a stepped mesh structure, wherein the solvent has a dissolving effect on the materials with different pore sizes in step (1);

[0015] (5) Soaking the dried stepped mesh structure in a conductive solution so that the conductive filler in the conductive solution is evenly embedded in the hole wall of the stepped mesh structure, and then curing and drying in a vacuum drying oven to obtain a sensitive unit layer of the sensor.

[0016] Preferably, in step (1), the high molecular polymer comprises any one or more of polydimethylsiloxane (PDMS), E-coflex, hydrogel or thermoplastic elastomer (SEBS).

[0017] Preferably, in step (1), the materials with different pore sizes are divided into small-pore materials, medium-pore materials and large-pore materials, and the materials with different pore sizes are all sacrificial materials.

[0018] More preferably, the diameter of the small-pore material is 100-1000 nm, the diameter of the mesoporous material is 1 μm-1000 μm, and the diameter of the macroporous material is 1 mm-100 mm.

[0019] Further preferably, the sacrificial material comprises any one or more of salt particles, sugar particles, ice particles, PS microspheres, carbonyl iron powder, pure iron particles or aluminum particles.

[0020] Preferably, in step (1), the mass ratio of the pore material to the high molecular weight polymer in the mixed solution is 10 to 80:100.

[0021] Preferably, in step (4), the solvent is any one of deionized water, sulfuric acid or hydrochloric acid.

[0022] Preferably, in step (5), the conductive solution comprises any one or more of MXene, multi-walled carbon nanotubes, graphene, iron nanowires, silver nanowires, polyaniline (PANI) or 2-phenylpyridine (PPyh), and the solvent in the conductive solution is n-hexane, deionized water or ethanol.

[0023] 2. A method for preparing the flexible pressure sensor, comprising the following steps:

[0024] Electrodes are bonded to the lower surface of the sensitive unit layer to form an electrode layer, and a flexible packaging layer is used for packaging to obtain a flexible pressure sensor with a variable modulus structure.

[0025] Preferably, the adhesion is performed by using a pressure-sensitive adhesive tape, and the material of the flexible packaging layer is a pressure-sensitive adhesive tape.

[0026] The beneficial effects of the present invention are as follows: the present invention discloses a flexible pressure sensor with a variable modulus structure, comprising a flexible packaging layer, a sensitive unit layer and an electrode layer, wherein the sensitive unit layer is located above the electrode layer, and the flexible packaging layer wraps the sensitive unit layer and the electrode layer. In the flexible pressure sensor of the present invention, materials with different pore sizes are used to form material layers with different pore sizes and different thicknesses in a mold, and after melting the materials with different pore sizes in warm water, a stepped mesh structure is obtained, which is immersed in a conductive solution to form a sensitive unit layer, and has the following advantages: (1) Stepped mesh structure: a stepped mesh structure with a scale range from nanometer to millimeter, with distinct layers, and exhibiting good electrical and mechanical properties; (2) due to the different elastic moduli, surface areas and porosities of the large pores, hollow pores, small pores and the like in the stepped mesh, different pressure sizes have different compression effects on the variable modulus pressure sensor with a stepped mesh structure, exhibiting different but excellent mechanical and electrical properties. In addition, the high-porosity pore structure of the stepped mesh structure undergoes compression deformation under micro-force strain, which reflects the high sensitivity of the device. Under the action of pressure, the low-porosity pore structure undergoes compression deformation, increasing the contact area of MWCNT on the pore wall, and the device resistance continues to change, so that the device can still detect force changes under large pressure, broaden its stress response range, and improve the linearity of the sensor, so that the pressure sensor has high sensitivity and good linearity within a wide stress response range. (3) The structural advantages of the flexible pressure sensor of the present invention can be manifested in that it is easy to collect signals and data measurement is easier to achieve, the manufacturing method is simple, and it can be widely used in human posture detection in medicine, reflecting certain commercial value and medical value. In addition, with the deepening of research, it was found that the variable modulus flexible pressure sensor with a stepped mesh structure has many advantages: high linearity can obtain more accurate data for research and diagnosis; a large stress response range can provide a wider test range for flexible pressure sensors; higher sensitivity can track data more accurately and quickly, making the test results more accurate; the preparation cost is low, the process is simple, and it can be widely used in the market. It has great application prospects in the adaptable fields of flexible pressure sensors such as intelligent robots, health monitoring, human-computer interaction, smart medical equipment, and smart wearable systems.

[0027] Other advantages, objects, and features of the present invention will be described in part in the following description and, in part, will be apparent to those skilled in the art upon examination of the following description or may be learned from practice of the present invention. The objects and other advantages of the present invention may be realized and obtained through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention will be described in detail below with reference to the accompanying drawings, in which:

[0029] Figure 1 This is a flow chart for preparing the sensitive unit layer and the electrode layer in Example 1;

[0030] Figure 2 This is an SEM image of the salt mixed layer prepared in step (2) of Example 1;

[0031] Figure 3 This is an SEM image of the transition stage between the salt mixing layer and the sugar mixing layer of the flexible pressure sensor with a variable modulus structure prepared in step (3) of Example 1;

[0032] Figure 4 This is an SEM image of the sugar mixed layer prepared in step (3) of Example 1;

[0033] Figure 5 This is the pressure-current relationship curve of the flexible pressure sensor with variable modulus structure prepared in Example 1;

[0034] Figure 6 The time response of the flexible pressure sensor with a variable modulus structure in Example 1 under a pressure of 18 kPa is shown in the left and right illustrations, respectively, as the response curves of the flexible pressure sensor with a variable modulus structure in Example 1 under compression and contact pressure rebound.

[0035] Figure 7 The response of the flexible pressure sensor with a variable modulus structure under continuous pressure in Example 1;

[0036] Figure 8 This is the repeated durability of the flexible pressure sensor with a variable modulus structure under a pressure of 21 kPa in Example 1. The three illustrations from left to right are the response curves of 100 to 110 times, 6000 to 6010 times, and 10000 to 10010 times, respectively. DETAILED DESCRIPTION

[0037] The following describes the embodiments of the present invention by means of specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the illustrations provided in the following embodiments are only schematic illustrations of the basic concept of the present invention, and the following embodiments and features in the embodiments can be combined with each other without conflict.

[0038] Example 1

[0039] A flexible pressure sensor with a variable modulus structure, wherein the preparation process of the sensitive unit layer and the electrode layer is as follows Figure 1 The specific preparation method is as follows:

[0040] (1) Next, weigh 0.1 g of salt and 0.1 g of PDMS solution, stir them to mix them evenly to obtain a salt mixed solution, and spread the salt mixed solution in the prepared mold (the mold is a cylindrical hole with a diameter of 10 mm and a height of 5 mm). The thickness of the salt mixed layer after spreading is about 1 mm.

[0041] (2) Next, 0.45 g of white sugar and 0.32 g of PDMS solution were weighed and stirred to mix them evenly to obtain a sugar mixed solution. The sugar mixed solution was then evenly spread in the mold of step (1). The thickness of the sugar mixed layer after spreading was about 4 mm. The lower layer in the mold was the salt mixed layer, and the upper layer was the sugar mixed layer.

[0042] (3) The mold was then placed in a vacuum drying oven at 80°C for curing for 5 hours and then taken out to obtain a mixed solid.

[0043] (4) The mixed solid was immersed in deionized water at 50°C for 30 h to dissolve the sugar and salt in the mixed solid, and then vacuum dried to obtain a step-like network structure.

[0044] (5) Finally, multi-walled carbon nanotube powder (MWCNT) and n-hexane are mixed in a mass ratio of 0.3:100, and the multi-walled carbon nanotubes are evenly mixed and distributed in the n-hexane solution under ultrasonic oscillation. After stirring evenly with a glass rod, a multi-walled carbon nanotube solution is formed. The stepped mesh structure dried in step (4) is immersed in the multi-walled carbon nanotube solution for 1 minute to allow the MWCNT to be evenly embedded in the hole wall of the stepped mesh structure, thereby obtaining a stepped mesh structure with uniformly distributed MWCNT. The structure is then placed in a vacuum drying oven for curing and drying to obtain a sensitive unit layer.

[0045] (6) Using interdigital electrodes as electrodes, the interdigital electrodes are adhered to the lower surface of the sensitive unit layer using pressure-sensitive tape to form an electrode layer.

[0046] (7) The sensitive unit layer and electrode layer prepared above are encapsulated using a pressure-sensitive adhesive tape to form a variable modulus flexible pressure sensor based on a stepped mesh structure.

[0047] Example 2

[0048] A flexible pressure sensor with a variable modulus structure, the specific preparation method is as follows:

[0049] (1) Next, weigh 0.2 g of salt and 0.2 g of PDMS solution, stir them to mix them evenly to obtain a salt mixed solution, and spread the salt mixed solution in the prepared mold (the mold is a cylindrical hole with a diameter of 10 mm and a height of 5 mm). The thickness of the salt mixed layer after spreading is about 2 mm.

[0050] (2) Next, weigh 0.45 g of white sugar and 0.22 g of PDMS solution, stir them to mix evenly to obtain a sugar mixed solution, and continue to spread the sugar mixed solution evenly in the mold of the above step (1). The thickness of the sugar mixed layer after spreading is about 3 mm. The lower layer in the mold is the salt mixed layer, and the upper layer is the sugar mixed layer.

[0051] (3) The mold was then placed in a vacuum drying oven at 80°C for curing for 5 hours and then taken out to obtain a mixed solid.

[0052] (4) The mixed solid was immersed in deionized water at 60°C for 30 h to dissolve the sugar and salt in the mixed solid, and then vacuum dried to obtain a step-like network structure.

[0053] (5) Finally, multi-walled carbon nanotube powder (MWCNT) and n-hexane are mixed in a mass ratio of 0.3:100, and the multi-walled carbon nanotubes are evenly mixed and distributed in the n-hexane solution under an ultrasonic oscillation environment. After stirring evenly with a glass rod, a multi-walled carbon nanotube solution is formed. The stepped mesh structure dried in step (5) is immersed in the multi-walled carbon nanotube solution for 1 minute to allow the MWCNT to be evenly embedded in the hole wall of the stepped mesh structure to obtain a stepped mesh structure with uniform MWCNT distribution. The structure is placed in a vacuum drying oven for curing and drying to obtain a sensitive unit layer.

[0054] (6) Using interdigital electrodes as electrodes, the interdigital electrodes are adhered to the lower surface of the sensitive unit layer using pressure-sensitive tape to form an electrode layer.

[0055] (7) The sensitive unit layer and electrode layer prepared above are encapsulated using a pressure-sensitive adhesive tape to form a variable modulus flexible pressure sensor based on a stepped mesh structure.

[0056] Example 3

[0057] The "polydimethylsiloxane (PDMS)" in Example 1 is replaced by "E-coflex" and the "multi-walled carbon nanotube powder (MWCNT)" is replaced by "iron nanowire" to obtain a flexible pressure sensor with a variable modulus structure.

[0058] Example 4

[0059] The "polydimethylsiloxane (PDMS)" in Example 1 is replaced by "hydrogel", the "salt particles" are replaced by "carbonyl iron powder", the "sugar particles" are replaced by "ice particles", and the "multi-walled carbon nanotube powder (MWCNT)" is replaced by "silver nanowires" to obtain a flexible pressure sensor with a variable modulus structure.

[0060] Example 5

[0061] Replace the "polydimethylsiloxane (PDMS)" in Example 1 with "thermoplastic elastomer (SEBS)", "salt particles" with "aluminum particles", "sugar particles" with "PS balls", and replace "multi-walled carbon nanotube powder (MWCNT)" with "graphene" to obtain a flexible pressure sensor with a variable modulus structure.

[0062] Example 6

[0063] Replace the "polydimethylsiloxane (PDMS)" in Example 1 with "thermoplastic elastomer (SEBS)", "salt particles" with "pure iron particles", "sugar particles" with "ice particles", and replace "multi-walled carbon nanotube powder (MWCNT)" with "polyaniline (PANI)" to obtain a flexible pressure sensor with a variable modulus structure.

[0064] Example 7

[0065] The "polydimethylsiloxane (PDMS)" in Example 1 is replaced by "thermoplastic elastomer (SEBS)", the "salt particles" are replaced by "PS balls", the "sugar particles" are replaced by "carbonyl iron powder", the "multi-walled carbon nanotube powder (MWCNT)" is replaced by "2-phenylpyridine (PPyh)", and the "interdigitated electrode" is replaced by "parallel plate electrode" to obtain a flexible pressure sensor with a variable modulus structure.

[0066] Performance Testing

[0067] Figure 2 This is the SEM image of the salt mixed layer prepared in step (2) of Example 1. Figure 2 It can be seen that the pore size of the salt particles is about 500 μm, and the salt pores are evenly distributed. It is expected to improve the stability of the sensor when used to prepare the sensor.

[0068] Figure 3 This is an SEM image of the transition stage between the salt mixed layer and the sugar mixed layer of the flexible pressure sensor with variable modulus structure prepared in step (3) of Example 1. Figure 3 It can be seen that in the transition stage, the salt pores and sugar pores have a clear dividing line; the holes in the transition stage are connected, which can be used to prepare the sensor and ensure the sensing performance of the sensor at the transition surface between the salt pores and sugar pores.

[0069] Figure 4 This is a SEM image of the sugar mixed layer prepared in step (3) of Example 1. Figure 4 It can be seen that the pore size of the sugar particles is about 1000 μm and the salt pores are evenly distributed. They can be used to prepare sensors, which is expected to improve the stability of the sensors.

[0070] Figure 5 The pressure-current relationship curve of the flexible pressure sensor with variable modulus structure prepared in Example 1. Figure 5 It can be seen that the sensor has a stress response range of up to 553kPa in the range of 0-1270kPa. -1 The sensitivity is very good, with good linearity up to 97%, and the sensor performance is excellent.

[0071] Figure 6 The time response of the flexible pressure sensor with variable modulus structure in Example 1 under 18kPa pressure is shown in the figure on the left and right. The response curves of the flexible pressure sensor with variable modulus structure in Example 1 when subjected to compression and contact pressure rebound are shown on the left and right. Figure 6 It can be seen that when subjected to a pressure of 180 kPa, the sensor's response time is 150 ms. After the pressure is removed, the sensor's recovery time is 100 ms.

[0072] Figure 7 The response of the flexible pressure sensor with variable modulus structure under continuous pressure in Example 1 is shown in FIG. Figure 7 It can be seen that the sensor can distinguish different pressures; under different pressures, the sensor responds stably.

[0073] Figure 8 The three illustrations from left to right are the response curves of the flexible pressure sensor with variable modulus structure under 21 kPa pressure in Example 1, which are intercepted at 100 to 110 times, 6000 to 6010 times, and 10000 to 10010 times respectively. Figure 8 It can be seen that the sensor has a repeated durability of up to 11,000 times, and the response curves of 100-110 times, 6,000-6,010 times, and 10,000-10,010 times are basically the same, reflecting the good stability of the sensor.

[0074] The relevant performances of the flexible pressure sensors with variable modulus structures prepared in Examples 2 to 7 were tested. Similarly, it can be seen that the flexible pressure sensors with variable modulus structures prepared by using the sensitive unit layer of the present invention can improve the stability, sensitivity, stress response range of the sensor and shorten the response time.

[0075] In summary, the present invention discloses a flexible pressure sensor with a variable modulus structure, which comprises a flexible packaging layer, a sensitive unit layer and an electrode layer from top to bottom. In the flexible pressure sensor of the present invention, materials with different pore sizes are used to form material layers with different pore sizes and different thicknesses in a mold. After the materials with different pore sizes are melted in warm water, a stepped mesh structure is obtained, which is immersed in a conductive solution to form a sensitive unit layer. The flexible pressure sensor has the following advantages: (1) Stepped mesh structure: a stepped mesh structure with a scale range from nanometer to nectar, with distinct layers, exhibiting good electrical and mechanical properties; (2) due to the different elastic moduli, surface areas and porosities of the large pores, hollow pores and small pores in the stepped mesh, different pressures have different compression effects on the variable modulus pressure sensor with a stepped mesh structure, exhibiting different but excellent mechanical and electrical properties. In addition, the high-porosity pore structure of the stepped mesh structure undergoes compression deformation under micro-force strain, which reflects the high sensitivity of the device. Under the action of pressure, the low-porosity pore structure undergoes compression deformation, increasing the contact area of MWCNT on the pore wall, and the device resistance continues to change, so that the device can still detect force changes under large pressure, broaden its stress response range, and improve the linearity of the sensor, so that the pressure sensor has high sensitivity and good linearity within a wide stress response range. (3) The structural advantages of the flexible pressure sensor of the present invention can be manifested in that it is easy to collect signals and data measurement is easier to achieve, the manufacturing method is simple, and it can be widely used in human posture detection in medicine, reflecting certain commercial value and medical value. In addition, with the deepening of research, it was found that the variable modulus flexible pressure sensor with a stepped mesh structure has many advantages: high linearity can obtain more accurate data for research and diagnosis; a large stress response range can provide a wider test range for flexible pressure sensors; higher sensitivity can track data more accurately and quickly, making the test results more accurate; the preparation cost is low, the process is simple, and it can be widely used in the market. It has great application prospects in the adaptable fields of flexible pressure sensors such as intelligent robots, health monitoring, human-computer interaction, smart medical equipment, and smart wearable systems.

[0076] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not limiting. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention can be modified or replaced by equivalents without departing from the purpose and scope of the technical solutions, which should all be included in the scope of the claims of the present invention.

Claims

1. A flexible pressure sensor with a variable modulus structure, characterized in that: The flexible pressure sensor comprises a flexible packaging layer, a sensitive unit layer and an electrode layer, wherein the sensitive unit layer is located above the electrode layer, and the flexible packaging layer wraps the sensitive unit layer and the electrode layer; The material of the flexible packaging layer is piezoresistive tape or plastic film, with a thickness of 1 μm to 500 μm; The electrode layer is an interdigitated electrode or a parallel plate electrode, and the electrode material in the electrode layer is any one of aluminum foil, silver foil or copper foil; The thickness of the sensitive unit layer is 1 mm to 500 mm and is prepared according to the following method: (1) materials with different pore sizes are mixed with a high molecular polymer solution respectively, and stirred to mix them uniformly to obtain mixed solutions with different pore sizes; (2) transferring the mixed solutions of different pore sizes into the mold in sequence. The order of transferring the mixed solutions of different pore sizes can be arbitrarily combined to form material layers of different pore sizes and different thicknesses; (3) placing the mold in a vacuum drying oven and curing it, then taking it out to obtain a mixed solid; (4) immersing the mixed solid in a solvent to melt the materials with different pore sizes in the mixed solid, and vacuum drying to obtain a stepped mesh structure, wherein the solvent has a dissolving effect on the materials with different pore sizes in step (1); (5) Soaking the dried stepped mesh structure in a conductive solution so that the conductive filler in the conductive solution is evenly embedded in the hole wall of the stepped mesh structure, and then curing and drying in a vacuum drying oven to obtain a sensitive unit layer of the sensor.

2. The flexible pressure sensor according to claim 1, characterized in that In step (1), the high molecular weight polymer comprises any one or more of polydimethylsiloxane, E-coflex, hydrogel or thermoplastic elastomer.

3. The flexible pressure sensor according to claim 1, characterized in that In step (1), the materials with different pore sizes are divided into small-pore materials, medium-pore materials and large-pore materials, and the materials with different pore sizes are all sacrificial materials.

4. The flexible pressure sensor according to claim 3, characterized in that: The diameter of the small-pore material is 100-1000 nm, the diameter of the mesoporous material is 1 μm-1000 μm, and the diameter of the macroporous material is 1 mm-100 mm.

5. The flexible pressure sensor according to claim 3, characterized in that: The sacrificial material includes any one or more of salt particles, sugar particles, ice particles, PS microspheres, carbonyl iron powder, pure iron particles or aluminum particles.

6. The flexible pressure sensor according to claim 1, characterized in that In step (1), the mass ratio of the pore material to the high molecular weight polymer in the mixed solution is 10 to 80:

100.

7. The flexible pressure sensor according to claim 1, characterized in that In step (4), the solvent is any one of deionized water, sulfuric acid or hydrochloric acid.

8. The flexible pressure sensor according to claim 1, characterized in that: In step (5), the conductive solution comprises any one or more of MXene, multi-walled carbon nanotubes, graphene, iron nanowires, silver nanowires, polyaniline or 2-phenylpyridine, and the solvent in the conductive solution is n-hexane, deionized water or ethanol.

9. The method for preparing the flexible pressure sensor according to any one of claims 1 to 8, characterized in that: The preparation method comprises the following steps: Electrodes are adhered to the lower surface of the sensitive unit layer to form an electrode layer, and a flexible packaging layer is used for packaging to obtain a flexible pressure sensor with a variable modulus structure.

10. The preparation method according to claim 9, characterized in that The adhesion adopts pressure-sensitive adhesive tape, and the material of the flexible packaging layer is pressure-sensitive adhesive tape.

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