A flexible piezoresistive pressure sensor and a method for preparing the same

Abstract

The present invention discloses a flexible piezoresistive pressure sensor and a preparation method thereof, belonging to the technical field of flexible sensing devices. The sensor is assembled in sequence by a substrate layer, an electrode layer, a conductive pressure-sensitive layer, an elastomer layer having a parallel ridge microstructure or a spiral ridge microstructure, and a packaging layer; the elastomer layer is prepared by a microelectronic printing method based on an ink prepared by dissolving a low modulus elastomer material in an organic solvent. The overall preparation process is simple and highly repeatable, and the prepared sensor has a high sensitivity (20.13 kPa ‑1 ), and has a wide linear range of 0~35 kPa (R 2 =0.988), and good cycle stability, with a response time of less than 0.4 s. Integrating the sensor with an electrochromic display device can realize pressure visualization, making it easier for the naked eye to intuitively distinguish the pressure size, and has good application prospects in health monitoring, human-computer interaction and other fields.

Description

Technical Field

[0001] The present invention relates to the technical field of flexible sensing equipment, and in particular to a flexible piezoresistive pressure sensor and a preparation method thereof. Background Art

[0002] Flexible pressure sensors are highly flexible, thin, and highly integrated. They can be attached to tortuous surfaces such as human skin and have broad application prospects in research fields such as electronic skin, health monitoring, wearable electronic devices, and human-computer interaction. Highly sensitive flexible pressure sensors can also collect various vital signs such as breathing, heart rate, and pulse, and have attracted much attention in the field of flexible sensing.

[0003] Pressure sensors can be divided into different types according to their working principles, such as piezoresistive, piezoelectric and capacitive. Compared with other types of pressure sensors, piezoresistive pressure sensors have the advantages of simple structure, wide linear range and high stability. They are the most commonly used sensor types on the market. In order to improve the sensitivity of piezoresistive sensors, research is generally conducted from the two aspects of sensor structure and material. Among them, microstructured piezoresistive pressure sensors (i.e., microstructures are constructed on the sensing layer of piezoresistive pressure sensors) have the characteristics of high linearity and high sensitivity. The resistance of this type of sensor is mainly composed of contact resistance and series body resistance. External pressure stimulation causes the elastic body to deform, which will cause the contact resistance to change, and then the magnitude of the force can be fed back.

[0004] Microstructures are mainly constructed through the reverse template method, in which finely structured templates are mainly prepared by methods such as laser etching or 3D printing. The microstructured elastomers obtained by this type of preparation method have high controllability and high precision, but the preparation process of this type of method is relatively complex and the production cost is high; plant surfaces with microstructure textures in nature can also be used as molds for making microstructures. Although this preparation method can effectively control costs, it has poor controllability and repeatability and is not suitable for mass production. In addition, when using the template method to prepare an elastomer with a microstructure on the surface, it is necessary to separate it from the template after it solidifies, and the demolding process is likely to cause damage to the microstructure.

[0005] In order to solve the shortcomings of traditional microstructure construction methods, Chinese patent CN 117245934 B proposes a flexible stretch sensor based on microelectronic printing. The document points out that based on special ink, a flexible stretch sensing layer is formed on the surface of the substrate using microelectronic printing technology and a ridge-shaped microstructure is constructed. The sensitivity of the sensing layer can be effectively improved, and the flexible stretch sensor prepared on this basis has ultra-high toughness and stability. From this, it is thought that if the microstructure elastomer of the flexible piezoresistive pressure sensor can be directly prepared using microelectronic printing technology, it should also be possible to further improve the performance of the device without destroying the microstructure morphology, and this type of process also has the advantage of high repeatability. However, there has been no reference example in the prior art of successfully constructing a piezoresistive pressure sensor using microelectronic printing technology, and the specific preparation scheme and microelectronic printing parameters are still unclear.

[0006] In addition, traditional pressure sensor data is mainly displayed through electronic equipment output, which requires the use of larger external devices, which does not meet the requirements of lightweight devices. If the flexible piezoresistive pressure sensor can be integrated with the electrochromic device to achieve real-time visualization of the pressure size, it may not only reduce the size of the device, but also combine the advantages of the electrochromic device to further reduce energy consumption. The corresponding solution also needs further exploration. Summary of the invention

[0007] The purpose of the present invention is to solve the problems existing in the prior art and to provide a flexible piezoresistive pressure sensor and a preparation method thereof. The present application utilizes microelectronic printing technology to prepare the elastomer layer of the sensor and constructs a microstructure thereon. The device has a stable structure, high sensitivity and strong repeatability. After integrating it with an electrochromic display device, the external pressure stimulus to the sensor can be directly reflected and displayed through the electrochromic display device, thereby achieving real-time visual display of pressure changes and saving energy consumption at the same time.

[0008] In order to achieve the above technical objectives, the present invention is implemented by the following technical solutions: a method for preparing a flexible piezoresistive pressure sensor, comprising the following steps:

[0009] 1) Prepare ink: dissolve the low modulus elastomer material in an organic solvent at room temperature;

[0010] 2) Prepare conductive slurry: add ethylene glycol and Tween 20 to PEDOT:PSS slurry and mix well;

[0011] 3) Pretreatment of substrate layer and encapsulation layer;

[0012] 4) Preparation of the elastomer layer: On a microelectronic printing device platform, the ink prepared in step 1) is used to print an elastomer film on the encapsulation layer. After drying, the ink in step 1) is used to print a microstructure on the side of the film facing away from the encapsulation layer.

[0013] 5) Preparation of a conductive pressure-sensitive layer: coating the conductive slurry prepared in step 2) on the surface of the elastomer layer to prepare a conductive pressure-sensitive layer;

[0014] 6) Printing interdigital electrodes: On the microelectronic printing equipment platform, conductive silver interdigital electrodes are printed on the substrate layer using conductive silver paste;

[0015] 7) The silver interdigitated electrodes are packaged relative to the conductive pressure-sensitive layer.

[0016] Furthermore, in step 1), the low modulus elastomeric material is one or more of styrene-butadiene block copolymer (SBS) and styrene-butadiene-styrene triblock copolymer (SEBS); the organic solvent is any one of toluene, N,N-dimethylformamide, and dichloromethane; and the mass fraction of the elastomeric material after being dissolved in the organic solvent is 25-35%.

[0017] Furthermore, in step 2), the volume fraction of ethylene glycol is 1-10%, and the volume fraction of Tween 20 is 0.1-1%.

[0018] Furthermore, in step 4), the printing parameters for printing the elastomeric film are: the needle specification is 25 G, the printing speed is 8~15 mm / s, and the air pump pressure is 60~100 kPa; the printing parameters for printing the parallel ridge microstructure are: the printing needle specification is 32 G, the air pump pressure is 80~100 kPa, and the printing speed is 1~3 mm / s.

[0019] The present application utilizes low modulus elastomeric materials to construct microstructures. The surface microstructure of the elastomeric layer can undergo significant deformation under extremely small external force stimulation, thereby adding more conductive pathways and causing greater resistance changes, thereby producing more obvious signal changes, which helps to improve the sensitivity of the pressure sensor.

[0020] Furthermore, the microstructure refers to parallel ridges or spiral ridges printed on the elastomeric film, the spacing between adjacent parallel ridges is 0.2-0.4 mm, and the spacing between adjacent spiral ridges in the inner and outer circles is 0.2-0.4 mm.

[0021] Furthermore, the printing parameters for printing the silver interdigital electrodes in step 6) are: the printing needle specification is 27G, the printing speed is 3-5 mm / s, the air pump pressure is 200-300 kPa, and the electrode spacing is 300-400 μm.

[0022] Furthermore, the coating method in step 5) is drop coating or spin coating, and after coating, it needs to be heated at 30-50° C. for 2-3 hours to form a film.

[0023] Furthermore, the base layer and the encapsulation layer are any one of PET film, PDMS film, PI film, PC film and PVC film.

[0024] The flexible piezoresistive pressure sensor prepared by the above method has a high sensitivity (20.13 kPa -1 ), and has a wide linear range of 0~35 kPa (R 2 = 0.988), and good cycle stability; integrating it with a specially made electrochromic display device can realize real-time visualization of pressure changes. The specific preparation steps of the electrochromic display device are as follows:

[0025] S1. Preparation of active layer slurry: Add ethylene glycol and Tween 20 to PEDOT:PSS slurry and mix well;

[0026] S2. Preparation of electrolyte layer slurry: sodium polystyrene sulfonate, titanium dioxide, polyacrylamide aqueous solution, glycerol and deionized water are mixed and stirred;

[0027] S3, a method based on microelectronic printing, using the slurry prepared in step S1 to prepare a patterned PEDOT:PSS electrochromic active material layer on the top and bottom substrates, the printing parameters are: the printing needle specification is 34 G, the printing speed is 30-40 mm / s, and the air pump pressure is 10-50 kPa;

[0028] S4, based on the microelectronic printing method, the silver electrode layer was prepared on the top and bottom PEDOT:PSS layers. The printing parameters were as follows: the printing needle specification was 27 G, the printing speed was 3-8 mm / s, and the air pump pressure was 200-280 kPa;

[0029] S5. Based on the microelectronic printing method, the electrolyte layer slurry prepared in step S2 is used to prepare the electrolyte layer on the top silver electrode layer. The printing parameters are: the printing needle specification is 27 G, the printing speed is 3-8 mm / s, and the air pump pressure is 80-140 kPa;

[0030] S6. Encapsulate the top electrolyte layer and the bottom silver electrode layer face to face.

[0031] Furthermore, in step S1, the volume fraction of ethylene glycol is 1-10%, and the volume fraction of Tween 20 is 0.1-1%; in step S2, the mass concentration of the polyacrylamide aqueous solution is 30-60%, and the mass ratio of sodium polystyrene sulfonate, titanium dioxide, polyacrylamide aqueous solution, glycerol and deionized water is 4.0-5.0:1.0-2.0:0.8-1.2:2.0-3.0:1.0-4.0.

[0032] The beneficial effects of the present invention are:

[0033] 1. The present application uses thermoplastic materials as elastomers, which have low elastic modulus, low cost, good solubility, and good biocompatibility. The viscosity of the ink prepared by the thermoplastic materials is controllable, and the preparation method is simple and the conditions are mild, which is suitable for microelectronic printing technology;

[0034] 2. The present application uses microelectronic printing technology to prepare an elastomer layer with a microstructure, which can be directly patterned and designed to construct microstructures of different morphologies without the need for additional templates, thus avoiding tensile damage caused during demolding. In addition, the preparation process is simple, with high precision, fast preparation speed, strong repeatability, and can be used for mass production.

[0035] 3. The flexible piezoresistive pressure sensor prepared by the microelectronic printing technology of the present application has a parallel ridge microstructure or a spiral ridge microstructure on the elastomer layer. By further limiting the microstructure morphology and the ridge spacing, the prepared sensor has a high sensitivity (20.13 kPa -1 ), and has a wide linear range of 0~35 kPa (R 2 =0.988), as well as good cycle stability. In the compression cycle test of > 4500 times, it showed good fatigue resistance and a response time of less than 0.4 s. The sensor has great application potential in the fields of health monitoring, human-computer interaction and electronic skin.

[0036] 4. This application integrates a flexible piezoresistive pressure sensor with a specially made electrochromic display device. After the flexible pressure sensor receives external stimuli of different degrees, the electrochromic display device directly reflects the performance. Compared with the electronic screens currently available on the market, it not only realizes the real-time visualization of pressure changes, but also has the effect of saving energy consumption;

[0037] 5. The flexible piezoresistive pressure sensor disclosed in this application has a simple preparation process and low preparation cost. It is expected to become a feasible choice for the application of low-cost and functional sensor devices in the future, and also provides new ideas for the development of corresponding fields. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1Schematic diagram of the structure of the flexible piezoresistive pressure sensor and the electrochromic display device disclosed in the present application, wherein (a) shows the structure of the flexible piezoresistive pressure sensor, and (b) shows the structure of the electrochromic display device;

[0039] Figure 2 are surface and cross-sectional morphology images of the elastomer microstructure prepared in the present application, wherein (a) is a local morphology image of the elastomer layer having a surface microstructure with parallel convex ridges prepared in Example 1, (b) is a local morphology image of the elastomer layer having a surface microstructure with spiral convex ridges prepared in Example 2, and (c) is a cross-sectional image of the elastomer layer having a surface microstructure with parallel convex ridges prepared in Example 1;

[0040] Figure 3 The sensitivity comparison diagram of the flexible piezoresistive pressure sensor device prepared based on the elastomer layer with different morphological microstructures on the surface, wherein (a) is a sensitivity comparison diagram of the sensor with parallel ridges with different spacings printed on the elastomer layer prepared in Example 1, and (b) is a sensitivity comparison diagram of the sensor with spiral ridges with different spacings printed on the elastomer layer prepared in Example 2;

[0041] Figure 4 1 is a stability test diagram of a flexible pressure sensor prepared based on an elastomer with a parallel ridge microstructure with a spacing of 0.4 mm on the surface disclosed in Example 1, wherein (a) is the relative change of current under cyclic pressure> 4500 times, and (b) is the response time;

[0042] Figure 5 This is a simulation diagram of the flexible pressure sensor in Application Example 1 acting on the human body, wherein (a) is a wrist pulse monitoring diagram, and (b) is a throat swallowing action monitoring diagram;

[0043] Figure 6 yes Figure 5 (a) A partial enlarged view of the dotted box in the inset;

[0044] Figure 7 This is the real-time display diagram corresponding to the electrochromic display device when the flexible pressure sensor is visualized using different pressure stimuli. DETAILED DESCRIPTION

[0045] The following examples further illustrate the content of the present invention, but should not be construed as limiting the present invention. Without departing from the essence of the present invention, modifications and substitutions made to the methods, steps or conditions of the present invention all fall within the scope of the present invention.

[0046] The SEBS used in this application is produced by Kraton of the United States (G1645, hardness 35A); PEDOT:PSS is produced by Heraeus (Clevios PH1000); polyacrylamide (molecular weight 5 million); Tween 20 is produced by Macklin; sodium polystyrene sulfonate is produced by Thermo Fisher Scientific; conductive silver paste is produced by Sai Ya Electronic Paste Co., Ltd. (01L-2211D); ethylene glycol and toluene are produced by Sinopharm Group; titanium dioxide is produced by Aladdin (10-25 nm); propylene glycol is produced by Anaiji.

[0047] Example 1: Preparation of a flexible piezoresistive pressure sensor

[0048] 1) Preparation of ink: Styrene-butadiene-styrene triblock copolymer (SEBS) was dissolved in toluene solvent at room temperature to prepare a uniform solution with a mass fraction of 30%.

[0049] 2) Preparation of conductive slurry: Place 1 g of poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonic acid) (PEDOT:PSS) slurry (PH1000, 1.0 wt%) in a 5 mL glass sample bottle, add 6 vol% ethylene glycol (EG) and 0.5 vol% Tween 20, and stir magnetically at room temperature for 30 min to mix well.

[0050] 3) Pretreatment of the encapsulation layer: treat the polyethylene terephthalate (PET) film in a plasma cleaner at 200 W for 2 min and dry it for later use.

[0051] 4) Microelectronics printing SEBS film: The pretreated PET film was fixed on the microelectronics printing equipment platform (model: Musashi ΩX-350), and the ink prepared in step 1) was placed in the syringe. The printing needle specification was 25 G, the printing speed was 10 mm / s, the air pump pressure was 80 kPa, and the SEBS film with a printing size of 10×10 mm was printed and dried.

[0052] 5) Printing SEBS film microstructure: Continue to use the ink prepared in step 1) for printing, change the printing needle to 32 G, the air pump pressure to 100 kPa, the printing speed to 3 mm / s, and coat according to the pattern drawn by AutoCAD software to prepare a SEBS film with a parallel ridge microstructure on the surface as the elastomer layer, such as Figure 2 As shown in the middle panel (a), the parallel ridges on the film are parallel to one side of the film. The cross-section of a single parallel ridge is semicircular and 90 μm high. The spacing between adjacent parallel ridges is 0.2 mm.

[0053] For comparison, the same conditions were used to print out a SEBS elastomer layer film with no ridge microstructure on the film surface, and a SEBS film with a parallel ridge microstructure on the surface and the spacing between adjacent parallel ridges was 0.3 mm and 0.4 mm respectively as the elastomer layer.

[0054] 6) Preparation of conductive pressure-sensitive layer: Use a pipette to take 20 μL of the conductive slurry prepared in step 2) and drop it on the surface of the SEBS film with different structures prepared in step 5), and heat it at 50°C for 2 h to form a conductive pressure-sensitive layer.

[0055] 7) Microelectronic printing of interdigitated electrodes: The pretreated PET film is fixed as a substrate on the microelectronic printing equipment platform, and the conductive silver paste is placed in the syringe. The printing needle specification is 27 G, the printing speed is 4 mm / s, the air pump pressure is 230 kPa, the electrode spacing is 300 μm, and the conductive silver interdigitated electrodes are printed.

[0056] 8) Packaging: The silver interdigital electrodes and the conductive pressure-sensitive layer are packaged relative to each other to obtain a flexible piezoresistive pressure sensor.

[0057] The structure of the flexible piezoresistive pressure sensor prepared in this embodiment is as follows: Figure 1 As shown in the middle panel (a), the device includes a packaging layer, an elastomer layer, a pressure-sensitive layer, interdigitated electrodes and a substrate from top to bottom.

[0058] Example 2: Preparation of a flexible piezoresistive pressure sensor

[0059] In this embodiment, only step 5) is different from that in embodiment 1, and steps 1) to 4) and steps 6) to 8) are the same as those in embodiment 1.

[0060] Step 5 of this embodiment): Printing SEBS film microstructure: Printing is performed using the ink prepared in step 1), the printing needle is changed to 32 G, the air pump pressure is 100 kPa, the printing speed is 3 mm / s, and the pattern drawn by AutoCAD software is coated to prepare a SEBS film with a spiral ridge microstructure on the surface. The morphology of the spiral ridge microstructure is similar to that of a disc-shaped mosquito coil, see Figure 2 The middle panel (b) shows a partial view of the spiral ridge. The cross-section of the spiral ridge is also semi-circular and 90 μm high. The spacing between adjacent ridges in the inner and outer circles is 0.2 mm.

[0061] For comparison, the same conditions were used to print a SEBS elastomer layer film with no ridges on the film surface, and a SEBS film with a spiral ridge microstructure on the surface and the spacing between the inner and outer adjacent spiral ridges was 0.3 mm and 0.4 mm respectively as the elastomer layer.

[0062] The sensitivity of the sensors prepared based on elastomers with different morphologies prepared in Examples 1 and 2 was tested, and the results were as follows: Figure 3 As shown, from Figure 3 It can be seen that compared with the sensor without microstructure, the current variation range of the sensor with surface microstructure is greatly improved. Among them, the sensor with parallel ridge microstructure on the surface and the spacing between adjacent parallel ridges is 0.4 mm not only has the highest sensitivity (20.13 kPa -1 ), while having 0-35 kPa (R 2 = 0.988) wide linear sensing range ( Figure 3 (red dashed line X-axis range in panel (a)).

[0063] The relative change of current of a flexible pressure sensor based on an elastomer layer with a parallel ridge microstructure on the surface (the spacing between adjacent parallel ridges is 0.4 mm) under cyclic pressure > 4500 times was tested. The results are shown in Figure 4 ,From the figure, we can see that the sensor has good fatigue resistance, and after testing, the response time is less than 0.4 s.

[0064] Application Example 1

[0065] The flexible pressure sensor prepared based on the elastomer layer with parallel ridge microstructure (distance between adjacent parallel ridges is 0.4 mm) disclosed in Example 1 was applied to different parts of the human body for simulation testing. The instrument model is Keithley 4200-SCS semiconductor analysis tester.

[0066] The flexible piezoresistive pressure sensor is attached to the human wrist to test the current changes of the human pulse. The results are as follows Figure 5 (a) Small picture and Figure 6 As shown, it can be seen that as the wrist pulse beats, the current fluctuates, which indicates that the sensor can feedback the tiny strain of the pulse beat.

[0067] The flexible piezoresistive pressure sensor was pasted on the human throat to test the current changes when the throat swallowed. The results are as follows Figure 5 As shown in the middle panel (b), the sensor deforms as the human body swallows, and the conductive pathway is continuously connected and disconnected, forming periodic current fluctuations.

[0068] In summary, this sensor has good application prospects in the field of human motion detection.

[0069] Application Example 2

[0070] In this application example, the flexible piezoresistive pressure sensor with a spacing of 0.4 mm between adjacent parallel ridges on the elastomer layer prepared in Example 1 is integrated with an electrochromic display device.

[0071] The preparation process of the electrochromic display device is as follows:

[0072] 1) Preparation of active layer slurry: Place 1 g of poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonic acid) (PEDOT:PSS) slurry (PH1000, 1.0 wt%) in a 5 mL glass sample bottle, add 6 vol% ethylene glycol (EG) and 0.5 vol% Tween 20, and stir magnetically at room temperature for 30 min to mix well.

[0073] 2) Preparation of electrolyte layer slurry: 0.1 g polyacrylamide was dissolved in 0.2 g deionized water to prepare a polyacrylamide solution; sodium polystyrene sulfonate, titanium dioxide, polyacrylamide solution, glycerol and deionized water were mixed in a mass ratio of 4.0:1.0:0.8:2.0:1.0 and magnetically stirred at room temperature for 30 min.

[0074] 3) Based on the microelectronic printing method, the patterned PEDOT:PSS electrochromic active material layer was printed on the pretreated top and bottom PET substrates using the active layer slurry prepared in step 1), with a printing needle specification of 34 G, a printing speed of 30 mm / s, and an air pump pressure of 30 kPa.

[0075] 4) Prepare silver electrode layers on the top and bottom PEDOT:PSS layers based on microelectronic printing, with a 27 G tip, 4 mm / s printing speed, and 230 kPa air pump pressure;

[0076] 5) Based on the microelectronic printing method, the electrolyte layer is printed on the top silver electrode layer using the electrolyte layer slurry prepared in step 2), the printing needle specification is 27 G, the printing speed is 4 mm / s, and the air pump pressure is 100 kPa.

[0077] 6) The top electrolyte layer and the bottom silver electrode layer are packaged face to face to complete the preparation.

[0078] Figure 7Display, under the control of the single-chip microcomputer, when the flexible sensor receives different pressures, the electrochromic display device displays different numbers in real time: when the pressure is 0, the electrochromic device displays the number 0; when the pressure is about 1.786 kPa, the electrochromic device displays the number 1; when the pressure is about 17.86 kPa, the electrochromic device displays the number 2. Based on this corresponding display relationship, a standard curve or calculation formula for the applied pressure and the displayed number can be established, and then the unknown pressure applied to the sensor can be obtained through the corresponding conversion, realizing the real-time visualization of the pressure change. In addition, the corresponding proportional relationship between the displayed number and the applied pressure on the electrochromic display device can be adjusted by changing the single-chip microcomputer program, thereby adjusting the pressure perception accuracy.

[0079] The integrated device can provide real-time feedback on changes in applied pressure while reducing energy consumption, and has broad application prospects.

[0080] The above shows and describes the basic principles, main features and advantages of the present invention. However, the above is only a specific embodiment of the present invention, and the technical features of the present invention are not limited thereto. Any other implementation methods derived by any technician in the field without departing from the technical solution of the present invention should be included in the patent scope of the present invention.

Claims

1. A method for preparing a flexible piezoresistive pressure sensor, characterized in that: The steps include: 1) Prepare ink: dissolve the low modulus elastomer material in an organic solvent at room temperature; 2) Prepare conductive slurry: add ethylene glycol and Tween 20 to PEDOT:PSS slurry and mix well; 3) Pretreatment of substrate layer and encapsulation layer; 4) Preparation of the elastomer layer: On a microelectronic printing device platform, the ink prepared in step 1) is used to print an elastomer film on the encapsulation layer. After drying, the ink in step 1) is used to print a microstructure on the side of the film facing away from the encapsulation layer. 5) Preparation of a conductive pressure-sensitive layer: coating the conductive slurry prepared in step 2) on the surface of the elastomer layer to prepare a conductive pressure-sensitive layer; 6) Printing interdigital electrodes: On the microelectronic printing equipment platform, conductive silver interdigital electrodes are printed on the substrate layer using conductive silver paste; 7) The silver interdigital electrodes are packaged relative to the conductive pressure-sensitive layer; In step 4), the printing parameters for printing the elastomer film are: the needle specification is 25 G, the printing speed is 8-15 mm / s, and the air pump pressure is 60-100 kPa; the printing parameters for printing the microstructure are: the printing needle specification is 32 G, the air pump pressure is 80-100 kPa, and the printing speed is 1-3 mm / s; The microstructure refers to parallel ridges or spiral ridges printed on the elastomer film, the spacing between adjacent parallel ridges is 0.2-0.4 mm, and the spacing between adjacent spiral ridges in the inner and outer circles is 0.2-0.4 mm; In step 1), the low modulus elastomeric material is one or more of styrene-butadiene block copolymer and styrene-butadiene-styrene triblock copolymer; the mass fraction of the elastomeric material after being dissolved in an organic solvent is 25-35%.

2. The method for preparing a flexible piezoresistive pressure sensor according to claim 1, characterized in that: The organic solvent is any one of toluene, N,N-dimethylformamide and dichloromethane.

3. The method for preparing a flexible piezoresistive pressure sensor according to claim 1, characterized in that: In step 2), the volume fraction of ethylene glycol is 1-10%, and the volume fraction of Tween 20 is 0.1-1%.

4. The method for preparing a flexible piezoresistive pressure sensor according to claim 1, characterized in that: The printing parameters for printing the silver interdigital electrodes in step 6) are: the printing needle specification is 27 G, the printing speed is 3-5 mm / s, the air pump pressure is 200-300 kPa, and the electrode spacing is 300-400 μm.

5. The method for preparing a flexible piezoresistive pressure sensor according to claim 1, characterized in that: The coating method in step 5) is drop coating or spin coating, and after coating, it needs to be heated at 30~50℃ for 2~3 hours to form a film.

6. A flexible piezoresistive pressure sensor, characterized in that: The invention is prepared based on the preparation method described in any one of claims 1 to 5.

Images