A flexible pressure sensor and its preparation method

Abstract

The present invention discloses a flexible pressure sensor, whose structure sequentially includes: a first electrode layer, a first compressible resistance layer, a flexible conductive polymer layer, a second compressible resistance layer, and a second electrode layer. The first electrode layer and the second electrode layer are conductive fabrics and are connected to an external measurement circuit. The first compressible resistance layer and the second compressible resistance layer are conductive materials with a plurality of equally spaced protrusions, and the conductive materials are flexible and compressible. The resistance value of the flexible conductive polymer layer is constant. This solution constructs a special pressure sensor structure by using flexible materials, enabling the sensor to be applicable to pressure detection in any flexible environment. At the same time, the sensor material is lightweight, highly sensitive, and low in manufacturing cost, and can be widely applied in the fields of wearable devices, medical rehabilitation, automotive safety monitoring, etc.

Description

Technical Field

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

[0002] With the application and popularization of intelligent consumer electronic products, sensors, as essential core components, will have an important impact on the design and development direction of future intelligent products. Under certain special environments and special signals, the expected values and ideal requirements for various performance parameters such as the measurement range, accuracy, and stability of gas, pressure, humidity, etc. are gradually increasing. The application requirements for sensors are also getting higher and higher, posing new challenges to ordinary sensors. In recent years, with the development of flexible matrix materials, the research and development of new sensors have started to develop in the direction of meeting the requirements of flexibility, extensibility, free bending or even folding, portability, and wearability. The new flexible sensor has a flexible structure form, good flexibility and extensibility, can be arranged according to different detection environments and conditions, and can detect complex measured quantities, and can be applied to emerging electronic product fields such as medical health monitoring, sports monitoring, medical rehabilitation, and human-machine interface.

[0003] Traditional pressure sensors are generally divided into piezoresistive sensors, piezoelectric sensors, and capacitive sensors according to the sensing elements and sensing mechanisms used. Flexible pressure sensors are mostly piezoresistive sensors and composite sensors due to the properties of flexible substrates. In the selection of flexible substrates, materials such as polydimethylsiloxane, polyvinylidene fluoride, silicone rubber, and polyimide are often used as the substrate materials for flexible pressure sensors, which have good flexibility, conductivity, and piezoresistive characteristics. Existing flexible pressure sensors have low sensitivity and flexibility when applied to an array detection environment due to the limitations of the sensor structure and flexible substrate materials, and cannot be accurately applied to the detection environment of flexible materials. Summary of the Invention

[0004] The purpose of the present invention is to provide a flexible pressure sensor and a preparation method thereof, as well as an array-type flexible pressure sensor, which are all realized by flexible materials, have high sensitivity, are flexible and lightweight, and can be widely applied to pressure detection in the wearable field, aiming to overcome the problems existing in the above-mentioned prior art.

[0005] To achieve the above purpose, the technical solutions adopted by the present invention include the following aspects.

[0006] A flexible pressure sensor, whose structure sequentially includes: a first electrode layer, a first compressible resistance layer, a flexible conductive polymer layer, a second compressible resistance layer, and a second electrode layer. The first electrode layer and the second electrode layer are conductive fabrics and are connected to an external measurement circuit. The first compressible resistance layer and the second compressible resistance layer are conductive materials with a plurality of equally spaced protrusions, and this conductive material is flexible and compressible. The resistance value of the flexible conductive polymer layer is constant.

[0007] Further, the thickness of the first electrode layer and the second electrode layer is 0.01 mm to 0.1 mm, the thickness of the first compressible resistance layer and the second compressible resistance layer is 0.01 mm to 0.1 mm, and the thickness of the flexible conductive polymer layer is 0.02 mm to 0.1 mm.

[0008] Further, the distance between the protrusions of the first compressible resistance layer and the second compressible resistance layer is 0.01 mm to 0.5 mm.

[0009] Even further, the protrusions are conductive fabrics or conductive polymer materials.

[0010] Even further, the area size of the protrusions of the first compressible resistance layer and the second compressible resistance layer is 0.0001 mm 2 ~0.25 mm 2 .

[0011] Further, the composition of the conductive polymer layer includes, by mass percentage: 45 - 60% of polyolefin copolymer, 30 - 45% of conductive filler, 2 - 4% of inorganic auxiliary agent, 4 - 6% of titanate coupling agent, 0.8 - 2% of plasticizer, and 0.4 - 1.2% of antioxidant.

[0012] Even further, the polyolefin copolymer is a blend of polypropylene and polyethylene with a blend ratio of 1:1, and the conductive filler is any one or more of graphite, carbon black, and carbon nanotubes, and preferably carbon black is used.

[0013] Further, equally spaced flexible isolation layers are provided on the upper and lower surfaces of the conductive polymer layer. This isolation layer is an insulating material with a thickness of 0.01 mm to 0.1 mm, and the distance between the flexible isolation layers on the same side of the conductive polymer layer is 2 mm to 10 mm.

[0014] Further, a protective layer is also provided on the outer surfaces of the first electrode layer and the second electrode layer facing away from the compressible resistance layer. This protective layer is an insulating plastic film or an insulating fabric.

[0015] In order to achieve the above invention purpose, the present invention also provides a method for preparing the above flexible pressure sensor, and the steps are as follows:

[0016] S1. Prepare a conductive polymer layer with a constant resistance;

[0017] S2. Prepare protrusions with a thickness of 0.01 mm to 0.1 mm, a spacing of 0.01 mm to 0.5 mm, and an area size of 0.0001 mm 2 to 0.25 mm 2 ;

[0018] S3. Lay the lower electrode material flat, and then lay the protrusions, conductive polymer layer, protrusions, and upper electrode material on the lower electrode material in sequence, and encapsulate the edges to form a flexible pressure sensor;

[0019] The preparation process of the conductive polymer layer in step S1 is as follows:

[0020] S11. Heat 45 - 60% of the polyolefin copolymer raw material to a molten state, add 30 - 45% of the conductive filler, and stir rapidly;

[0021] S12. Add 2 - 4% of the inorganic auxiliary filler, 4 - 6% of the titanate coupling agent, 0.8 - 2% of the plasticizer, and 0.4 - 1.2% of the antioxidant in sequence, and stir rapidly;

[0022] S13. Pour the mixture into a mold, cool it to room temperature, and take out the conductive polymer layer in the mold.

[0023] Furthermore, the preparation process of the protrusions in step S2 adopts the following methods:

[0024] Lay the conductive fabric flat, and form protrusions with a height of 0.01 mm to 0.1 mm and an area of 0.0001 mm 2 to 0.25 mm 2 on the surface by laser engraving;

[0025] Or, lay the conductive polymer layer prepared in step S1 flat, and form protrusions with a height of 0.01 mm to 0.1 mm and an area of 0.0001 mm 2 to 0.25 mm 2 on the upper and lower surfaces by laser engraving;

[0026] Or, paste conductive yarns with a width of 0.01 mm to 0.5 mm on the surface of the electrode material through conductive glue, and cut them into protrusions with an area of 0.0001 mm 2 to 0.25 mm 2 ;

[0027] Furthermore, in step S11, the polyolefin copolymer is a copolymer of polypropylene and polyethylene, the ratio of the copolymer is 1:1, the heating temperature is 170 - 210 °C, and the blending and stirring time is 5 - 10 min.

[0028] Further, the step S13 further includes subsequent heat treatment of the conductive polymer layer taken out of the mold, specifically by gradually raising the temperature to 100-120°C, maintaining for 1.5-3 hours, and then slowly cooling with the furnace temperature to improve the thermal stability of the conductive polymer layer.

[0029] To achieve the above invention purpose, the present invention also provides an array pressure detection device using the above flexible pressure sensor, including a sensor array composed of at least two flexible pressure sensors, a collection circuit, a control circuit, and an analysis circuit. The collection circuit is connected to the first electrode layer and the second electrode layer of the flexible pressure sensor. The control circuit controls the collection circuit and the analysis circuit, and the analysis circuit analyzes the collected data information to determine the position where the array pressure detection device bears pressure.

[0030] In summary, due to the adoption of the above technical solutions, the present invention has at least the following beneficial effects:

[0031] This solution constructs a special pressure sensor structure by using flexible materials, enabling the sensor to be applicable to pressure detection in any flexible environment. At the same time, the sensor material is lightweight, highly sensitive, and low in manufacturing cost, and can be widely applied in the fields of wearable devices, medical rehabilitation, and automotive safety monitoring. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 is a schematic structural diagram of a flexible pressure sensor according to an embodiment of the present invention.

[0033] Figure 2 is a schematic structural diagram of a flexible pressure sensor when pressed according to an embodiment of the present invention.

[0034] Figure 3 is a schematic structural diagram of a flexible pressure sensor according to another embodiment of the present invention.

[0035] Figure 4 is a schematic structural diagram of a flexible pressure sensor when pressed according to another embodiment of the present invention.

[0036] Figure 5 is a curve graph showing the relationship between the resistance and pressure of a flexible pressure sensor according to an embodiment of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS:

[0038] 1 - First electrode layer, 2 - Second electrode layer, 3 - First compressible resistance layer, 4 - Second compressible resistance layer, 5 - Flexible conductive polymer layer, 6 - Protrusion, 7 - Isolation layer. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0039] The present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments, so as to make the purpose, technical solution and advantages of the present invention more clear and understandable. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0040] A flexible pressure sensor, as Figure 1 shown, the structure sequentially includes: a first electrode layer 1, a first compressible resistance layer 3, a flexible conductive polymer layer 5, a second compressible resistance layer 4, and a second electrode layer 2. The first electrode layer 1 and the second electrode layer 2 are conductive fabrics and are connected to an external measurement circuit. The first compressible resistance layer 3 and the second compressible resistance layer 4 are conductive materials with a plurality of equally spaced protrusions 6, and this conductive material has flexible compressible properties. The resistance value of the flexible conductive polymer layer 5 is constant.

[0041] In the present invention, a special pressure sensor structure is constructed by using flexible materials. The electrode layer on the surface of the sensor senses the external pressure. The compressible resistance layer between the electrode layer and the flexible conductive polymer layer deforms with the external pressure. As Figure 2 shown, this causes the resistance value between the two electrode layers to change. When the external pressure is greater, the deformation degree of the compressible resistance layer is greater, and the resistance value between the electrode layers is smaller. Therefore, the change in the external pressure can be judged according to the change in the resistance value between the first electrode layer and the second electrode layer.

[0042] In the present invention, the first electrode layer 1 and the second electrode layer 2 are ordinary conductive fabrics in the prior art, which can conduct electricity on both sides or on one side. When it is a single-sided conductive fabric material, the conductive surface faces the compressible resistance layer. The thickness of the electrode layer is generally 0.01 mm to 0.1 mm. The first compressible resistance layer 3 and the second compressible resistance layer 4 are both flexible and compressible conductive materials with a thickness of 0.01 mm to 0.1 mm. In actual use, the compressible resistance layer can be integrated with the electrode layer or with the conductive polymer layer. By a special preparation process, equally spaced protrusions 6 are formed on the surface of the conductive fabric or the conductive polymer material to become a compressible and deformable resistance layer between the electrode layer and the conductive polymer layer. Among them, the spacing between the protrusions 6 can be 0.01 mm to 0.5 mm, and the area size is 0.0001 mm 2 to 0.25 mm 2 , and the shape can be cylindrical, spherical or conical, etc.

[0043] The flexible conductive polymer layer 5 is a composite conductive polymer with a constant resistance value, and its thickness is 0.02 mm to 0.1 mm. To ensure the flexibility of the conductive polymer layer, in the present invention, its components include, by mass percentage: 45-60% of polyolefin copolymer, 30-45% of conductive filler, 2-4% of inorganic auxiliary agent, 4-6% of titanate coupling agent, 0.8-2% of plasticizer, and 0.4-1.2% of antioxidant. Among them, the polyolefin copolymer is a blend of polypropylene and polyethylene, and the blending ratio is between 1:3 and 3:1, and a ratio of 1:1 can be preferably used; the conductive filler is selected from graphite, carbon black, and carbon nanotubes, and in the present invention, carbon black with a diameter of 10-50 nm is preferably used as the conductive filler. The main function of the inorganic auxiliary agent is to improve the conductivity stability of the conductive polymer layer, and inorganic auxiliary agent fillers commonly used in the prior art can be used, specifically calcium carbonate, barium sulfate, mica, talc, etc.; the plasticizer is mainly used to ensure the flexibility of the prepared polymer, and plasticizers commonly used in the prior art can also be used, specifically dibutyl phthalate, dioctyl phthalate, tricresyl phosphate, triphenyl phosphate, chlorinated paraffin, etc.; the antioxidant can be selected from organic sulfide antioxidants, such as dithiocarbamates and mercaptobenzimidazoles. In the present invention, by adopting the above component ratio for the conductive polymer layer, good conductivity can be achieved on the basis of ensuring the flexibility and toughness of the material, and the resistance value remains unchanged when the conductive polymer material is arbitrarily pressed at room temperature.

[0044] In addition, in order to further improve the sensitivity of the sensor, flexible isolation layers 7 with equal intervals are also provided on the upper and lower surfaces of the conductive polymer layer 5, as Figure 3 and Figure 4 shown, blocking the contact between the compressible resistance layer and the polymer resistance layer in the initial state, and improving the accuracy and sensitivity of the initial detection. The isolation layer 7 is an insulating material, such as a plastic insulating film or insulating fabric, and its thickness is 0.01 mm to 0.1 mm. The distance between the flexible isolation layers on the same side of the conductive polymer layer can be set according to the actual size of the sensor, and can be 2 mm to 10 mm.

[0045] When the electrode layer is a conductive fabric, especially when a double-sided conductive fabric is used, for the convenience of use, a protective layer is also provided on the outer surfaces of the first electrode layer 1 and the second electrode layer 2 facing away from the compressible resistance layer, and the protective layer is an insulating plastic film or insulating fabric.

[0046] To achieve the object of the invention, the present invention also provides a method for preparing the above flexible pressure sensor, and the steps are as follows:

[0047] S1. Prepare a conductive polymer layer with a constant resistance value;

[0048] S2. Prepare protrusions with a thickness of 0.01 mm to 0.1 mm, a spacing of 0.01 mm to 0.5 mm, and an area size of 0.0001 mm 2 to 0.25 mm 2 ;

[0049] S3. Lay the lower electrode material flat, and then lay it on the lower electrode material in the order of protrusion, conductive polymer layer, protrusion, and upper electrode material in sequence, and encapsulate the edges to form a flexible pressure sensor;

[0050] The preparation process of the conductive polymer layer in step S1 is as follows:

[0051] S11. Heat 45 - 60% of the polyolefin copolymer raw material to a molten state, add 35 - 45% of the conductive filler, and stir rapidly;

[0052] Among them, the polyolefin copolymer is a copolymer of polypropylene and polyethylene, and the proportion of the copolymer is between 1:3 and 3:1, preferably a copolymerization ratio of 1:1; the melting heating temperature is 170 - 210 °C, and the blending and stirring time of the copolymer is 5 - 10 min; the conductive filler is selected from carbon - based conductive fillers, and any one or more of graphite, carbon black, and carbon nanotubes can be used. In the present invention, carbon black with a diameter of 10 - 200 nm is preferably used; after adding the conductive filler, the copolymer in the molten state is stirred rapidly, and the stirring time is 10 - 15 min.

[0053] S12. Add 2 - 4% of inorganic auxiliary filler, 4 - 6% of titanate coupling agent, 0.8 - 2% of plasticizer, and 0.4 - 1.2% of antioxidant in sequence, and stir rapidly for 1 - 2 hours;

[0054] The inorganic auxiliary can adopt the inorganic auxiliary fillers commonly used in the prior art, specifically calcium carbonate, barium sulfate, mica, talc, etc.; the plasticizer can also adopt the plasticizers commonly used in the prior art, specifically dibutyl phthalate, dioctyl phthalate, tricresyl phosphate, triphenyl phosphate, chlorinated paraffin, etc.; the antioxidant can be selected from organic sulfide antioxidants, such as dithiocarbamates and mercaptobenzimidazoles.

[0055] S13. Pour the mixture into a mold, cool it to room temperature, and it can be left standing for 1 - 2 h, and then take out the conductive polymer layer in the mold.

[0056] In the above step S13, the mixture can be cooled in two ways: air cooling and slow furnace cooling. When the slow furnace cooling method is used, the conductivity of the conductive polymer layer is more stable. The slow furnace cooling method is a commonly used cooling method in the prior art, and will not be elaborated in this invention. In addition, to further improve the thermal stability of the conductive polymer layer, post-heat treatment is also included for the conductive polymer layer taken out of the mold. The temperature is gradually increased to 100-120°C and maintained for 1.5-3h, and then slowly cooled with the furnace temperature.

[0057] The preparation process of the protrusions in step S2 can be carried out in three ways:

[0058] 1. Lay the conductive fabric flat and form protrusions on the surface by laser engraving; among them, the laser engraving technology is a mature processing technology and will not be described in detail here;

[0059] 2. Lay the conductive polymer layer prepared in step S1 flat and form protrusions on the upper and lower surfaces by laser engraving;

[0060] 3. Attach conductive yarns with a width of 0.01mm - 0.5mm to the surface of the electrode material through conductive glue, and then cut them into protrusions with a cutting machine.

[0061] Example 1

[0062] 11. Heat 20g of polyethylene and polypropylene copolymer to 180°C to form a molten state, add 16g of carbon black with an average diameter of 50nm, mix and stir for 10min;

[0063] 12. Add 1.2g of inorganic auxiliary calcium carbonate, 2.08g of titanate, 0.4g of dioctyl phthalate, and 0.32g of phosphite antioxidant in sequence, and continuously stir rapidly for 1 hour;

[0064] 13. Pour the mixture into a square mold, cool and solidify it at room temperature, and after standing for 2h, take out the prepared conductive polymer layer;

[0065] 14. Select a double-sided conductive fabric with a thickness of 0.2mm, and form columnar protrusions with a height of 0.1mm and an area of 0.01mm 2 on its surface by laser engraving, and the interval between the protrusions is 0.1mm;

[0066] 15. Cut the conductive fabric after engraving in step 14 into a square material with an area larger than the mold in step 13;

[0067] 16. After the conductive fabric is cut flat and the side with protrusions faces upward, the conductive polymer material is laid flat in the middle of the conductive fabric, and transparent insulating glue is applied to the surface of the conductive fabric (the area not covered by the conductive polymer material). Another conductive fabric of the same size with the side having protrusions facing downward is laid flat on the conductive fabric coated with glue, pressed tightly, and left stationary for 10 minutes to obtain the flexible pressure sensor of the present invention.

[0068] Place the flexible pressure sensor prepared in Example 1 in a pressure measurement environment, and the change relationship between the resistance change and the applied pressure value is as Figure 5 shown. From this curve relationship, it can be seen that the greater the pressure, the smaller the resistance value of the sensor. Therefore, the magnitude of the pressure on the sensor can be detected by measuring the resistance value data of the pressure sensor.

[0069] Example 2

[0070] 11. Pour 21 g of graphite powder into a container containing an appropriate amount of acetone, mix and stir at room temperature for 90 minutes, and then place it in a bellows to remove acetone;

[0071] 12. Take 33 g of polyolefin raw materials (here, polyethylene and polypropylene raw materials are mixed in a ratio of 1:1) and heat them to 190 °C to form a molten state, and continuously stir for 30 minutes;

[0072] 13. Add the graphite processed in step 11 to the molten polyolefin raw materials, and add 1.8 g of inorganic auxiliary calcium carbonate, 3 g of titanate, 0.72 g of dioctyl phthalate, and 0.4 g of antioxidant again, and continuously stir rapidly for 1.5 hours;

[0073] 14. Pour the mixture prepared in step 13 into a square mold (the height of the mold is greater than 2 mm), cool it in a furnace temperature, and after cooling to room temperature, let it stand for 2 hours;

[0074] 15. Take out the conductive polymer material prepared in the mold, and form conical protrusions with a height of 0.05 mm and an area of 0.25 mm 2 on the upper and lower surfaces by laser engraving. The interval between the protrusions is 0.5 mm;

[0075] 16. Take a double-sided conductive fabric with a thickness of 0.1 mm and cut it into a square with an area smaller than the size of the mold in step 14;

[0076] 17. Take an insulating plastic PET with a thickness of 0.1 mm and cut it into a square with an area equal to the size of the mold in step 14;

[0077] 18. After the flat cutting of the conductive fabric is completed, place the conductive polymer material between two pieces of conductive fabric, cover the upper and lower surfaces of the conductive fabric with insulating plastic PET, connect the upper and lower conductive fabrics at any corner with a wire and lead it out, and then encapsulate the edge of the material with insulating adhesive and press it tightly. Let it stand for 10 minutes to obtain the flexible pressure sensor of the present invention.

[0078] Connect the flexible pressure sensor prepared in Example 2 to the pressure measurement environment through a wire, and obtain the variation relationship (partial data) between the resistance change and the pressure value received as shown in Table 1 below. From this curve relationship, it can be seen that the greater the pressure, the smaller the resistance value of the sensor. Therefore, the magnitude of all pressures on the sensor can be detected by measuring the resistance value data of the pressure sensor.

[0079] Table 1 (Unit of applied pressure: KG, unit of measured resistance value: KΩ)

[0080]

[0081]

[0082] Due to its flexibility and stability, the above flexible pressure sensor can be widely used in the pressure detection of flexible environments. For example, when the sensor of the present invention is applied to an automotive seat, the seat pressure can be detected to improve safety; it can also be applied to a medical mattress or a children's mattress to monitor the pressure borne by the mattress. Therefore, the present invention also provides an array-type pressure detection device using the above flexible pressure sensor, including a flexible pressure sensor array, a collection circuit, a control circuit, and an analysis circuit. The collection circuit is connected to the first electrode layer and the second electrode layer of the flexible pressure sensor. The control circuit controls the collection circuit and the analysis circuit, and the analysis circuit analyzes the collected data information to determine the position where the array sensor bears pressure. Among them, the collection circuit uses the single-point polling collection or multi-point polling collection method commonly used in the prior art to collect the array-type pressure sensing data. The commonly used polling circuit generally uses multiple analog switch chips to poll and collect data, such as chips like AD7501, CD4051, 74HC4051, etc.

[0083] The above is only a detailed description of the specific embodiments of the present invention, rather than a limitation of the present invention. Various substitutions, variations, and improvements made by those skilled in the relevant technical fields without departing from the principles and scope of the present invention shall be included within the protection scope of the present invention.

Claims

1. A flexible pressure sensor, characterized in that, The structure sequentially includes: a first electrode layer, a first compressible resistance layer, a flexible conductive polymer layer, a second compressible resistance layer, and a second electrode layer. The first electrode layer and the second electrode layer are conductive fabrics and are connected to an external measurement circuit. The first compressible resistance layer and the second compressible resistance layer are conductive materials with a plurality of equally spaced protrusions, and the conductive materials are flexible and compressible. The resistance value of the flexible conductive polymer layer is constant, and the resistance value remains unchanged when the conductive polymer layer is arbitrarily pressed at room temperature.

2. The flexible pressure sensor according to claim 1, characterized in that, The thickness of the first electrode layer and the second electrode layer is 0.01 mm to 0.1 mm, the thickness of the first compressible resistance layer and the second compressible resistance layer is 0.01 mm to 0.1 mm, and the thickness of the flexible conductive polymer layer is 0.02 mm to 1 mm.

3. A flexible pressure sensor according to claim 1, characterized in that, The distance between the protrusions of the first compressible resistance layer and the second compressible resistance layer is 0.01 mm to 0.5 mm.

4. The flexible pressure sensor according to claim 1, characterized in that, The protrusions are conductive fabrics or conductive polymer materials.

5. A flexible pressure sensor according to claim 4, characterized in that, The area of the protrusions of the first compressible resistance layer and the second compressible resistance layer is 0.0001 mm 2 to 0.25 mm 2 .

6. The flexible pressure sensor according to claim 1, characterized in that, The composition of the conductive polymer layer includes, by mass percentage: 45 - 60% polyolefin copolymer, 30 - 45% conductive filler, 2 - 4% inorganic auxiliary agent, 4 - 6% titanate coupling agent, 0.8 - 2% plasticizer, and 0.4 - 1.2% antioxidant.

7. The flexible pressure sensor according to claim 6, characterized in that, The polyolefin copolymer is a blend of polypropylene and polyethylene, and the blending ratio is 1:

1. The conductive filler is any one or more of graphite, carbon black, and carbon nanotubes.

8. A flexible pressure sensor according to claim 1, wherein Flexible isolation layers with equal spacing are also provided on the upper and lower surfaces of the conductive polymer layer. The isolation layer is an insulating material with a thickness of 0.01 mm to 0.1 mm, and the distance between the flexible isolation layers on the same side of the conductive polymer layer is 2 mm to 10 mm.

9. A flexible pressure sensor according to any one of claims 1-8, characterized in that, A protective layer is also provided on the outer surfaces of the first electrode layer and the second electrode layer facing away from the compressible resistance layer. The protective layer is an insulating plastic film or an insulating fabric.

10. A method for preparing the flexible pressure sensor according to any one of claims 1 - 9, the steps are as follows: S1. Prepare a conductive polymer layer with a constant resistance value; S2. Prepare protrusions with a thickness of 0.01 mm to 0.1 mm, a spacing of 0.01 mm to 0.5 mm, and an area size of 0.0001 mm 2 to 0.25 mm 2 ; S3. Lay the lower electrode material flat, and then sequentially lay the protrusions, the conductive polymer layer, the protrusions, and the upper electrode material on the lower electrode material in this order, and encapsulate the edges to form a flexible pressure sensor; The preparation process of the conductive polymer layer in step S1 is as follows: S11. Heat 45 - 60% of the polyolefin copolymer raw material to a molten state, add 30 - 45% of the conductive filler, and stir rapidly; S12. Sequentially add 2 - 4% of the inorganic auxiliary agent filler, 4 - 6% of the titanate coupling agent, 0.8 - 2% of the plasticizer, and 0.4 - 1.2% of the antioxidant, and stir rapidly; S13. Pour the mixture into a mold, cool it to room temperature, and take out the conductive polymer layer in the mold.

11. The method according to claim 10, characterized in that, The preparation process of the protrusions in step S2 adopts the following method: The tiled conductive fabric has protrusions with a height of 0.01 mm to 0.1 mm and an area of 0.0001 mm 2 to 0.25 mm 2 formed on the surface by laser engraving; Alternatively, the conductive polymer layer prepared in step S1 is tiled, and protrusions with a height of 0.01 mm to 0.1 mm and an area of 0.0001 mm 2 to 0.25 mm 2 are formed on the upper and lower surfaces by laser engraving; Or paste the conductive yarn with a width of 0.01 mm to 0.5 mm on the surface of the electrode material through conductive adhesive, and cut it into protrusions with a height of 2 2 to 0.25 mm 2 and an area of 2 .

12. The method according to claim 10, characterized in that, In step S11, the polyolefin copolymer is a copolymer of polypropylene and polyethylene, and the copolymer ratio is 1:

1. The heating temperature is 170 - 210 °C, and the blending and stirring time is 5 - 10 min.

13. The method according to claim 10, wherein The step S13 further includes performing subsequent heat treatment on the conductive polymer layer taken out of the mold, specifically by gradually raising the temperature to 100-120°C, maintaining for 1.5-3 h, and then cooling with the furnace temperature.

14. An array pressure detection device for a flexible pressure sensor, characterized in that, It includes a sensor array composed of at least two flexible pressure sensors as described in claim 6 or 7, a acquisition circuit, a control circuit, and an analysis circuit. The acquisition circuit is connected to the first electrode layer and the second electrode layer of the flexible pressure sensor. The control circuit controls the acquisition circuit and the analysis circuit, and the analysis circuit analyzes the collected data information to determine the position where the array pressure detection device bears pressure.

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