An integrated flexible pressure sensor and a method for manufacturing the same

Abstract

The present application belongs to the field of flexible wearable sensors, and particularly relates to a kind of integrated flexible pressure sensor prepared by using three-dimensional polymer ion gel fiber with super high porosity.The present application provides an integrated flexible pressure sensor, the sensor includes dielectric layer and flexible electrode respectively bonded on the upper surface and lower surface of dielectric layer, the flexible electrode is polyimide conductive film, and the dielectric layer is polyimide ion gel fiber.The present application adds ionic liquid in polyamide acid to realize functionalization treatment, and then uses the simple processing technology of air jet spinning to prepare ion gel fiber with super high porosity;And in the air jet spinning process, polyamide acid conductive film is used as substrate to receive ion gel fiber, then compression and imidization treatment are carried out, and conductive silver wire is connected to obtain an integrated flexible pressure sensor;The problem of unstable sensor signal and structure caused by multi-layer structure is solved.

Description

Technical Field

[0001] The present invention belongs to the field of flexible wearable sensors, and specifically relates to an integrated flexible pressure sensor prepared by utilizing three-dimensional polymer ion gel fibers with ultra-high porosity. Background Art

[0002] Human skin is composed of three distinct functional layers: the epidermis, dermis (mesoderm), and subcutaneous tissue. These layers form a tough interface, allowing them to withstand a variety of complex mechanical forces and deformations. Similar to human skin, capacitive sensors are composed of upper and lower electrode layers and a dielectric layer. However, the different materials in the electrode and dielectric layers often exhibit significant differential moduli, leading to mechanical mismatch and differential deformation between the layers in practical applications. Furthermore, when sensors are subjected to complex forces and deformations over long periods of time, the interface structure is prone to slippage or misalignment, which is the primary cause of the sensor's low structural and signal stability.

[0003] Ionic liquids are typically composed of organic cations and inorganic (or organic) anions and are generally liquid at room temperature. They possess low volatility, structural designability, physicochemical stability, and health and environmental safety. Ionic liquids immobilized on solid substrates form materials called ion gels, which exhibit promising applications due to their dual properties of both ionic liquids and solid matrices.

[0004] Polymer ion gels, formed by blending high-molecular-weight organic polymers with ionic liquids, are solid-state mixtures with gel-like structures and ionic conductivity. By confining ionic liquids within three-dimensional polymer networks, ion gels with specific structures and properties can be formed. Due to the presence of ionic liquids, polymer ion gels possess many unique functionalities, such as electrical conductivity, excellent electrochemical stability, stability over a wide temperature range, and antifreeze and antibacterial properties. These materials have broad applications in energy storage, sensing, 3D printing, and biomedicine.

[0005] At present, there is no report in the existing technology on using ionic liquid to add to polyamic acid to process it into three-dimensional ion gel fibers with ultra-high porosity (porosity greater than 80%), and further using the three-dimensional ion gel fibers to prepare integrated flexible pressure sensors with stable welding interface junctions. Summary of the Invention

[0006] The object of the present invention is to provide an integrated flexible pressure sensor and a preparation method thereof. The present invention uses ultra-high porosity polyimide ion gel fiber produced by air-spinning as a dielectric layer, which can obtain good structural performance; polyimide is used as a high-modulus polymer material as a matrix, which provides excellent mechanical properties for the overall structure; at the same time, during the high-temperature imidization process of polyamic acid, structures with the same polyimide matrix occasionally form thermal welding interfaces, and excellent interface toughness is formed between the interfaces, so that the sensor can still obtain high signal stability under complex forces; thereby, an integrated flexible pressure sensor is produced; and the problem of sensor signal and structural instability caused by the multi-layer structure is solved.

[0007] The technical solution of the present invention:

[0008] The first technical problem addressed by the present invention is to provide an integrated flexible pressure sensor comprising a dielectric layer and flexible electrodes bonded to the upper and lower surfaces of the dielectric layer, respectively. The flexible electrodes are a polyimide conductive film, and the dielectric layer is a polyimide ion gel fiber. In the sensor obtained by the present invention, the ion gel dielectric layer enables the sensor to achieve an excellent high signal, the polyimide matrix provides excellent mechanical properties and signal stability, and the stable welding interfaces formed between the fibers and between the fibers and the electrodes result in a three-dimensional ion gel fiber sensor with high structural stability.

[0009] Furthermore, the polyimide ion gel fiber is produced by the following method: polyamic acid, ionic liquid, spinning aid, and solvent are uniformly mixed to form a spinning solution, the spinning solution is then subjected to an air-spinning method to produce polyamic acid ion gel fiber, and the polyimide ion gel fiber is obtained after imidization treatment; wherein the mass of the ionic liquid accounts for 10-57% of the total solid mass, the mass of the spinning aid accounts for 18-40% of the total solid mass, and the total solid mass = the mass of the polyamic acid + the mass of the ionic liquid + the mass of the spinning aid. The solid content of the spinning solution is 10-30%. The solid content is the proportion of the total solid mass in the spinning solution.

[0010] Furthermore, the ionic liquid includes one of: an imidazole ionic liquid, a piperidine ionic liquid, a pyridine ionic liquid, a quaternary amine ionic liquid or a quaternary phosphonium ionic liquid. The ionic liquid of the present invention needs to be resistant to high temperatures above 250°C.

[0011] Preferably, the ionic liquid is an imidazolium ionic liquid or a quaternary phosphonium ionic liquid; more preferably, it is an imidazolium ionic liquid.

[0012] Furthermore, the spinning aid includes polyacrylonitrile, polyvinyl pyrrolidone or polyethylene oxide, etc., to improve the spinnability of the spinning solution.

[0013] Furthermore, the solvent is selected from: N,N-dimethylformamide (DMF), tetrahydrofuran, acetonitrile or ethanol; the selected solvent can dissolve the spinning aid and polyamic acid.

[0014] The second technical problem to be solved by the present invention is to provide a method for preparing the above-mentioned integrated flexible pressure sensor, the preparation method comprising the following steps:

[0015] 1) uniformly mixing polyamic acid, an ionic liquid, a spinning aid and a solvent to prepare a spinning solution, then subjecting the spinning solution to an air-spinning method to prepare a polyamic acid ion gel fiber, and during the air-spinning process, using a polyamic acid conductive film as a substrate to collect fibers to prepare a polyamic acid conductive film loaded with the polyamic acid ion gel fiber;

[0016] 2) Then, two polyamic acid conductive membranes loaded with polyamic acid ion gel fibers are stacked in the order of polyamic acid conductive membrane-polyamic acid ion gel fiber-polyamic acid ion gel fiber-polyamic acid conductive membrane, and then compressed and imidized. Finally, the conductive wire is adhered to the polyimide conductive film (upper and lower electrodes) to obtain an integrated flexible pressure sensor.

[0017] Furthermore, the polyamic acid conductive film is prepared by the following method: the conductive filler dispersion is fully mixed with the polyamic acid solution, and then the polyamic acid conductive film is prepared by existing methods such as blade coating; the mass ratio of polyamic acid to conductive filler is: 85-90:10-15%.

[0018] Furthermore, the conductive filler includes carbon nanotubes, graphene, silver nanowires or carbon black.

[0019] Furthermore, the preparation method of the integrated flexible pressure sensor includes the following steps:

[0020] 1) stirring the ionic liquid and polyamic acid solution at room temperature for 0.5 to 1 hour to obtain an ionic liquid / polyamic acid mixed solution; the polyamic acid solution of the present invention is generally a thermoplastic polyimide precursor solution, preferably an ether anhydride polyimide;

[0021] 2) stirring the spinning aid and the solvent at room temperature for 2 to 5 hours to obtain a spinning aid solution;

[0022] 3) adding the spinning aid solution to the ionic liquid / polyamic acid mixed solution in step 1), and stirring the mixture at room temperature for 2 to 3 hours to obtain a spinning solution;

[0023] 4) preparing ion gel fibers by an air-spinning method using the spinning solution obtained in step 3); during the spinning process, collecting the fibers using a polyamic acid conductive membrane as a substrate to obtain a polyamic acid conductive membrane carrying the polyamic acid ion gel fibers;

[0024] 5) Using step 4), two polyamic acid conductive membranes loaded with polyamic acid ion gel fibers are obtained, and the two membranes are stacked in the order of polyamic acid conductive membrane-polyamic acid ion gel fiber-polyamic acid ion gel fiber-polyamic acid conductive membrane, followed by compression and imidization treatment; finally, the conductive wire is adhered to the upper and lower polyimide conductive membranes to obtain an integrated polyimide-based flexible pressure sensor.

[0025] Furthermore, in the air-jet spinning method of step 4), the air flow pressure of the air jet is 0.05-0.5 MPa, and the distance from the air jet to the receiving device (receiving cage) is 10-25 cm.

[0026] Furthermore, the process of the air-jet spinning method in step 4) is as follows: the obtained spinning solution is added to an injection pump, the aperture of the needle is 0.05-0.4 mm, and the feeding rate of the spinning solution is 0.01-0.05 ml / min; the air flow pressure of the jet nozzle is 0.05-0.5 MPa, and the distance from the jet nozzle to the receiving device (receiving cage) is adjusted to 10-25 cm; the fiber is obtained after collecting for 0.5-1 hour; the obtained fiber is left to stand at room temperature for 1-5 hours to allow the solvent to evaporate completely.

[0027] The third technical problem to be solved by the present invention is to point out the use of the above-mentioned integrated flexible pressure sensor in a smart insole.

[0028] Beneficial effects of the present invention:

[0029] The present invention adds ionic liquid to polyamic acid to achieve functionalization treatment, and then uses a simple air-spinning process to prepare ion gel fibers with ultra-high porosity (greater than 80%). Compared with non-structural polymer materials, they are more easily deformed. In the air-spinning process, a polyamic acid conductive film is used as a substrate to receive the ion gel fibers, and then compression and imidization treatment are performed to prepare an integrated flexible pressure sensor. This solves the problem of sensor signal and structural instability caused by the multi-layer structure.

[0030] The present invention also has the following advantages:

[0031] (1) The present invention utilizes a simple air-spinning method, which has the advantages of simple process, low cost, high yield, high energy efficiency, and environmental friendliness.

[0032] (2) The integrated flexible sensor prepared by the present invention can overcome the problems of fatigue under complex stress, interface stratification, packaging, unstable sensing signals, etc. caused by the multi-layer and multi-material characteristics of other flexible sensors; the present invention proposes a fiber stacking structure, which is characterized by rapid evaporation of the solvent during the airflow spinning process to form an overlapping interface, and different functional layers on the same substrate can form an integrated sensor device with a stable welding interface.

[0033] (3) The integrated flexible sensor prepared by the present invention has a polyimide matrix with excellent resistance to high and low temperatures, radiation resistance, good mechanical properties, etc., and can be used to solve the problem of sensor failure under extreme working conditions, high and low temperature impact and scene applications.

[0034] (4) The flexible, compressible, multifunctional integrated micro-nanofiber sensor prepared by the present invention is sensitive to pressure, bending and stretching. The three-dimensional porous nanofiber scaffold and elastic structure provide more contact resistance for the pressure sensor, and have a larger deformation space and rebound performance, thereby achieving high sensitivity, short response time, wide detection range, wide temperature range and high stability of sensing performance.

[0035] (5) The flexible, compressible, multifunctional integrated micro-nano fiber sensor prepared by the present invention can be applied to human health monitoring and detection of the full range of human motion. It can also be applied to the aerospace field, the electronic skin of space robots, or sensing detection in harsh environments. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 This is the SEM image of the fiber structure obtained in Example 1 of the present invention. Figure 1 It can be seen that the fiber structure obtained by the present invention is uniform and has high porosity.

[0037] Figure 2 This is the SEM image of the fiber-fiber welding point obtained in Example 1 of the present invention; Figure 2 It can be seen that a stable integrated interface is formed between the fibers.

[0038] Figure 3 This is the SEM image of the welding point between the fiber and the electrode film obtained in Example 1 of the present invention; Figure 3 It can be seen that a stable integrated interface is formed between the fiber and the electrode layer.

[0039] Figure 4 The sensitivity performance diagram of the sensor obtained in Example 1 of the present invention is shown in FIG. Figure 4 It can be seen that the flexible sensor of the present invention has excellent sensitivity.

[0040] Figure 5 The response time signal diagram of the sensor obtained in Example 1 of the present invention is shown in FIG. Figure 5 It can be seen that the response speed of the flexible sensor of the present invention is higher than that of human skin.

[0041] Figure 6 is a cyclic response stability performance diagram of the sensor obtained in Example 1 of the present invention; Figure 6 It can be seen that the flexible sensor of the present invention has service stability under ultra-high pressure.

[0042] Figure 7 Schematic diagram of the air-jet spinning process of the present invention. DETAILED DESCRIPTION

[0043] The polyimide-based ion gel fiber integrated flexible pressure sensor of the present invention can be prepared by the following preparation method: first, the ultrasonically treated conductive filler is added to the polyamic acid solution and fully mixed, and the polyamic acid conductive film is prepared by a doctor blade process; second, the ionic liquid is added to the polyamic acid solution, and then the spinning aid solution is added to prepare the polyamic acid-based spinning precursor solution; then, the spinning precursor solution is spun, wherein the collecting cage uses the polyamic acid conductive film as a substrate to collect the fibers; finally, the collected electrode-fiber-electrode is placed in a muffle furnace for high-temperature imidization treatment; under a high-temperature environment, local welding points are formed between the fibers and the fibers, and between the fibers and the electrode film, and finally an integrated polyimide-based ion gel flexible sensor with a stable welding interface is obtained.

[0044] In the present invention, the ionic liquid acts as a functional filler in the polymer material to achieve functional treatment of the fiber; the polyimide material serves as the structural matrix of the fiber, providing good mechanical properties for the three-dimensional structure, generally 2MPa to 8GPa; the spinning aid is used to enhance the spinnability of the ion gel and obtain a stable spinning effect.

[0045] In the present invention, different functional fillers are added to polyamic acid to achieve different functionalization treatments, adding conductive fillers as electrode layers and ionic liquids as dielectric layers. The ultra-high porosity ion gel fiber prepared by air-spinning can obtain good structural properties. Polyimide, as a high-modulus polymer material, serves as a matrix, providing excellent mechanical properties for the structure. At the same time, during the high-temperature imidization process of polyamic acid, structures with the same polyimide matrix occasionally form thermal welding interfaces, forming excellent interface toughness between the interfaces, so that the sensor can still obtain high signal stability under complex stresses.

[0046] The embodiments of the present invention will be described in detail below with reference to the examples, but those skilled in the art will appreciate that the following examples are intended only to illustrate the present invention and should not be construed as limiting the scope of the invention. Where specific conditions are not specified in the examples, the methods were performed according to conventional conditions or the conditions recommended by the manufacturer. Where the manufacturers of the reagents or instruments are not specified, they are all conventional products that can be purchased commercially.

[0047] Example 1

[0048] The steps for preparing an integrated flexible pressure sensor are as follows:

[0049] 1. Preparation of electrodes

[0050] 1) Add 2 g of carbon nanotubes to 198 g of N,N-dimethylformamide solvent and sonicate for 2 h to obtain a 1 wt% carbon nanotube dispersion;

[0051] 2) Add 22 g of the carbon nanotube dispersion to 10 g of the polyamic acid solution and stir magnetically for 3 h;

[0052] 3) The stirred solution was coated with a scraper to form a 500 μm film, which was placed in a 100° C. forced air oven for 1 hour to obtain a polyamic acid conductive film, which was then removed for later use;

[0053] 2. Preparation of spinning solution:

[0054] 1) adding 0.49 g of 1-ethyl-3-methylimidazolium tetrafluoroborate ionic liquid to 1.5 g of polyamic acid solution, wherein the mass concentration of the polyamic acid solution is 18%, and stirring at room temperature for 0.5 to 1 hour to obtain a mixed solution of ionic liquid / polyamic acid solution;

[0055] 2) Add 1 g of polyacrylonitrile to 9 g of N,N-dimethylformamide solvent and stir at room temperature for 2 to 5 hours to obtain a spinning aid solution;

[0056] 3) adding 2.2 g of the spinning aid solution to the mixed solution of the ionic liquid / polyamic acid solution in step 1), and stirring the solution at room temperature for 2 to 3 hours to obtain a spinning solution of the ion gel composite material;

[0057] 3. Preparation of ultra-high porosity three-dimensional polymer ion gel fibers and flexible pressure sensors:

[0058] 1) Add the spinning solution into a micro syringe pump with a needle diameter of 0.05-0.4 mm and a solution feeding rate of 0.05 ml / min;

[0059] 2) setting the air flow pressure of the air jet to 0.05-0.5 MPa and adjusting the distance from the air jet to the receiving cage to 10-25 cm; during the spinning process, collecting the fibers using the polyamic acid conductive film as a substrate, and collecting for 0.5-1 hour to obtain a polyamic acid conductive film loaded with polyamic acid ion gel fibers (a double-layer structure of three-dimensional ion gel fibers and polyamic acid conductive film);

[0060] 3) Two polyamic acid conductive membranes loaded with polyamic acid ion gel fibers are stacked in the order of polyamic acid conductive membrane (electrode)-polyamic acid ion gel fiber-polyamic acid ion gel fiber-polyamic acid conductive membrane (electrode), pre-compressed, and then placed in a muffle furnace for imidization treatment. The heating program is: 80°C, keep warm for 0.5h, 100°C, keep warm for 0.5h, 150°C, keep warm for 0.5h, 200°C, keep warm for 0.5h, 250°C, keep warm for 0.5h, and 300°C, keep warm for 1h; finally, the sample is cut into a size of 1cm×1cm, and a conductive silver wire is adhered to the upper and lower polyimide conductive films to obtain a polyimide-based ion gel fiber integrated flexible pressure sensor.

[0061] The fibers obtained in Example 1 were characterized using a scanning electron microscope. Figure 1 As shown by Figure 1 It can be seen that the ion gel fiber obtained by the present invention has an ultra-high porosity of 95%, and the fiber diameter is between 0.8 and 2 microns. The fiber structure is cut into samples of 0.7 cm × 0.7 cm × 0.9 mm, and the porosity is tested and calculated using the drainage method. The formula P = [(V0-V) / V0] * 100% is used for calculation, and V0 = 0.9 cm 3 , drain 0.042 ml of water, and calculate the porosity P = 95.33%. Figure 2 , 3 respectively show the stable fusion interface between the dielectric layer fibers and between the dielectric layer fibers and the electrode layer film in the sample.

[0062] The mechanical universal tensile testing machine and LCR bridge were used to test the capacitance of the flexible pressure sensor with pressure, and the sensitivity signal, response time and cycle stability of the flexible pressure sensor were measured. Figure 4 、 Figure 5 and Figure 6 As shown in the figure, the sensitivity can reach 158kPa -1 Above, the response time is within 5ms, and under the cyclic pressure of 2000kPa, it maintains high signal stability and structural stability.

[0063] Comparative Example 1

[0064] 1. Preparation of spinning solution:

[0065] 1) adding 0.7 g of 1-ethyl-3-methylimidazolium tetrafluoroborate ionic liquid to 1.5 g of polyamic acid solution, wherein the mass concentration of the polyamic acid solution is 18%, and stirring at room temperature for 0.5 to 1 hour to obtain a mixed solution of the ionic liquid / polyamic acid solution;

[0066] 2) Add 1 g of polyacrylonitrile to 9 g of N,N-dimethylformamide solvent and stir at room temperature for 2 to 5 hours to obtain a spinning aid solution;

[0067] 3) adding 2.2 g of the spinning aid solution to the mixed solution of the ionic liquid / polyamic acid solution in step 1), and stirring the solution at room temperature for 2 to 3 hours to obtain a spinning solution of the ion gel composite material;

[0068] 2. Preparation of ultra-high porosity three-dimensional polymer ion gel fibers:

[0069] 1) Add the spinning solution into a micro syringe pump with a needle diameter of 0.05-0.4 mm and a solution feeding rate of 0.05 ml / min;

[0070] 2) Set the airflow pressure of the nozzle to 0.05-0.5 MPa and adjust the distance from the nozzle to the receiving cage to 10-25 cm;

[0071] As a result, under the limited preparation parameters, the spinning solution of the sample could not form a fiber structure; the reason was that the ionic liquid content was too high and the spinning effect of the spinning solution could no longer meet the requirements of air-jet spinning.

[0072] Comparative Example 2

[0073] 1) adding 0.49 g of 1-ethyl-3-methylimidazolium tetrafluoroborate ionic liquid to 1.5 g of polyamic acid solution, wherein the concentration of the polyamic acid solution is 18%, and stirring at room temperature for 0.5 to 1 hour to obtain a mixed solution of ionic liquid / polyamic acid solution;

[0074] 2) Add 1 g of polyacrylonitrile to 9 g of N,N-dimethylformamide solvent and stir at room temperature for 2 to 5 hours to obtain a spinning aid solution;

[0075] 3) adding 1.5 g of the spinning aid solution to the mixed solution of the ionic liquid / polyamic acid solution in step 1), and stirring the solution at room temperature for 2 to 3 hours to obtain a spinning solution of the ion gel composite material;

[0076] 2. Preparation of ultra-high porosity three-dimensional polymer ion gel fibers:

[0077] 1) Add the spinning solution into a micro syringe pump with a needle diameter of 0.05-0.4 mm and a solution feeding rate of 0.05 ml / min;

[0078] 2) Set the airflow pressure of the nozzle to 0.05-0.5 MPa and adjust the distance from the nozzle to the receiving cage to 10-25 cm;

[0079] As a result, under the limited preparation parameters, the spinning solution of the samples could not form a fiber structure; the reason was that too little spinning aid was added, and the spinning solution had poor spinning effect under the influence of high content of ionic liquid and could not form a stable fiber structure.

Claims

1. An integrated flexible pressure sensor, comprising a dielectric layer and flexible electrodes bonded to the upper and lower surfaces of the dielectric layer, characterized in that: The flexible electrode is a polyimide conductive film, and the dielectric layer is a polyimide ion gel fiber; wherein, the polyimide ion gel fiber is prepared by the following method: first, polyamic acid, ionic liquid, spinning aid and solvent are evenly mixed to form a spinning solution, and then the spinning solution is subjected to an air-jet spinning method to prepare polyamic acid ion gel fiber, and the polyimide ion gel fiber is obtained after imidization treatment; wherein, the mass of the ionic liquid accounts for 10 to 57% of the total solid mass, the mass of the spinning aid accounts for 18 to 40% of the total solid mass, the total solid mass = the mass of the polyamic acid + the mass of the ionic liquid + the mass of the spinning aid, and the solid content of the spinning solution is 10 to 30%.

2. The integrated flexible pressure sensor according to claim 1, characterized in that: The ionic liquid includes: one of imidazole ionic liquid, piperidine ionic liquid, pyridine ionic liquid, quaternary amine ionic liquid or quaternary phosphonium ionic liquid.

3. The integrated flexible pressure sensor according to claim 2, characterized in that: The ionic liquid is an imidazole ionic liquid or a quaternary phosphonium ionic liquid.

4. The integrated flexible pressure sensor according to claim 3, characterized in that: The ionic liquid is an imidazole ionic liquid.

5. The integrated flexible pressure sensor according to claim 1, characterized in that: The spinning aid includes: polyacrylonitrile, polyvinyl pyrrolidone or polyethylene oxide.

6. The integrated flexible pressure sensor according to claim 1, characterized in that: The solvent is selected from: N,N-dimethylformamide, tetrahydrofuran, acetonitrile or ethanol.

7. The method for preparing an integrated flexible pressure sensor according to any one of claims 1 to 6, characterized in that: The preparation method comprises the following steps: 1) polyamic acid, ionic liquid, spinning aid and solvent are uniformly mixed to form a spinning solution, and the spinning solution is then subjected to an air-spinning method to prepare polyamic acid ion gel fiber. During the air-spinning process, a polyamic acid conductive film is used as a substrate to collect the fiber to prepare a polyamic acid conductive film loaded with polyamic acid ion gel fiber; 2) Then, two polyamic acid conductive membranes loaded with polyamic acid ion gel fibers are stacked in the order of polyamic acid conductive membrane-polyamic acid ion gel fiber-polyamic acid ion gel fiber-polyamic acid conductive membrane, and then compressed and imidized; finally, the conductive wire is adhered to the polyimide conductive membrane to obtain an integrated flexible pressure sensor.

8. The method for preparing an integrated flexible pressure sensor according to claim 7, characterized in that: The polyamic acid conductive film is prepared by the following method: a conductive filler dispersion is fully mixed with a polyamic acid solution, and then a polyamic acid conductive film is prepared; The mass ratio of polyamic acid to conductive filler is: 85-90:10-15; The conductive filler includes carbon nanotubes, graphene, silver nanowires or carbon black.

9. The method for preparing an integrated flexible pressure sensor according to claim 7, characterized in that: The method for preparing the integrated flexible pressure sensor comprises the following steps: 1) Stirring the ionic liquid and polyamic acid solution at room temperature for 0.5 to 1 hour to obtain an ionic liquid / polyamic acid mixed solution; 2) Stirring the spinning aid and the solvent at room temperature for 2 to 5 hours to obtain a spinning aid solution; 3) adding the spinning aid solution to the ionic liquid / polyamic acid mixed solution in step 1) and stirring thoroughly at room temperature for 2 to 3 hours to obtain a spinning solution; 4) preparing polyamic acid ion gel fibers by air-spinning the spinning solution obtained in step 3); during the spinning process, collecting the fibers using the polyamic acid conductive membrane as a substrate to obtain a polyamic acid conductive membrane carrying the polyamic acid ion gel fibers; 5) Using step 4), two polyamic acid conductive membranes loaded with polyamic acid ion gel fibers are obtained, and they are stacked in the order of polyamic acid conductive membrane-polyamic acid ion gel fiber-polyamic acid ion gel fiber-polyamic acid conductive membrane, followed by compression and imidization treatment; finally, conductive wires are adhered to the upper and lower polyimide conductive membranes to obtain an integrated flexible pressure sensor.

10. The method for preparing an integrated flexible pressure sensor according to claim 9, characterized in that: In the air-jet spinning method of step 4), the air flow pressure of the air jet is 0.05-0.5 MPa, and the distance from the air jet to the receiving device is 10-25 cm.

11. The method for preparing an integrated flexible pressure sensor according to claim 10, characterized in that: The process of the air-jet spinning method in step 4) is as follows: the obtained spinning solution is added to a syringe pump with a needle aperture of 0.05 to 0.4 mm and a feeding rate of the spinning solution of 0.01 to 0.05 ml / min; the air flow pressure of the jet nozzle is set to 0.05 to 0.5 MPa, and the distance from the jet nozzle to the receiving device is adjusted to 10 to 25 cm; the fiber is obtained after collecting for 0.5 to 1 hour; and the obtained fiber is allowed to stand at room temperature for 1 to 5 hours to allow the solvent to evaporate completely.

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