Preparation method and application of surface pyramid multistage ordered piezoresistive sensor

Abstract

The invention provides a preparation method and application of a surface pyramid multistage ordered piezoresistive sensor, and the method comprises the steps: firstly obtaining a Si substrate of which the surface is covered with a SiO2 film, and the crystal orientation of the Si substrate is lt; 100 gt; ; the surface of the SiO2 thin film is covered with a photoresist layer, a plurality of groups of dots are exposed on the photoresist layer, and each group is composed of three rows of dots which are arranged in parallel; after developing by using a developing solution, carrying out plasma etching on the exposed SiO2 so as to expose the Si substrate; removing the photoresist, and performing wet etching on the exposed Si by using a NaOH solution to obtain a silicon template; pouring a conductive material on the silicon template, heating and curing the conductive material, and stripping the conductive material from the silicon template to obtain the sensing layer of the surface pyramid multistage ordered piezoresistive sensor, the dependence of the sensor on the electrode contact area and compressibility is improved, and the sensitivity and the sensing range are improved.

Description

Technical Field

[0001] The invention belongs to the field of micro-nano structures, and relates to a surface pyramid multi-level ordered piezoresistive sensor, a preparation method and an application thereof. Background Art

[0002] Piezoresistive sensors are sensors made using the piezoresistive effect, which can convert pressure changes into changes in resistance. Piezoresistive sensors are widely used because of their small size, easy integration, simple structure, easy manufacturing, good frequency response, and ability to measure high-speed pulse pressure. Its main application areas include human motion detection, electronic skin, and human-computer interaction. In human motion detection, piezoresistive sensors can adapt to the bending pressure of joints of different sizes due to their advantages, and display the bending pressure changes through changes in current and resistance. It can be used in scenarios such as finger movement function assessment and finger movement rehabilitation training.

[0003] The performance of piezoresistive sensors is mainly reflected in high sensitivity and wide detection range. High sensitivity can distinguish subtle pressure stimulation of the sensor, and wide detection range can distinguish low pressure and high pressure of the sensor. The performance of the sensor mainly depends on two factors: first, the contact change between the functional layer and the electrode, mainly when the contact area between the piezoresistance layer and the electrode increases under the action of external force, resulting in a wider conductive path; second, the resistance change in the functional layer. In most cases, when the piezoresistance material is deformed under the action of external force, the conductive path becomes shorter. Therefore, the piezoresistive sensor requires that the pressure and the contact area between the piezoresistance material and the electrode are positively correlated, and the piezoresistance material also needs to have high compression performance.

[0004] Studies have shown that the microstructure of the functional layer surface can greatly improve the sensor's dependence on the electrode contact area and compressibility, and can improve sensitivity to a certain extent. The surface microstructures mainly include single micro-protrusion structures, such as columnar, hemispherical and pyramidal; composite micro-protrusion structures, such as porous pyramid structures, interlocking structures, multi-level columns, etc.; and three-dimensional porous structures. Compared with other structures, composite micro-protrusion structures can enhance deformation ability, increase specific surface area and improve overload resistance.

[0005] The current problem with piezoresistive sensors is how to balance sensitivity and sensing range. Summary of the invention

[0006] In view of the above problems, the present invention aims to propose a method for preparing a surface pyramid multi-level ordered piezoresistive sensor: In order to achieve the above objectives, this application is implemented through the following technical solutions: A surface pyramid multi-level ordered piezoresistive sensor, comprising: two silver electrodes with pins, and a piezoresistive functional layer located between the pins, wherein a multi-level and ordered micro-pyramid structure is distributed on the surface of the piezoresistive functional layer, and the functional layer contains multi-walled carbon nanotubes and graphene.

[0007] In order to achieve the above object, the present invention adopts the following scheme: a method for preparing a surface pyramid multi-level ordered piezoresistive sensor, comprising the following steps: S1, obtain the surface covered with SiO 2 The Si substrate of the thin film has a crystal orientation of <100> ; The SiO 2 The surface of the film is covered with a photoresist layer, on which a plurality of groups of dots are exposed, each group consisting of three rows of dots arranged in parallel; the number of dots in each row is not less than three; In the three rows of dots, the dots in each row have the same diameter, and the dots in different rows have different diameters. The dots of the three diameters are named circle one, circle two, and circle three from small to large. The three rows of dots are composed of circle one, circle two, and circle three in sequence. For any row of the three rows of dots, the dots are spaced equally, and the spacing is denoted by d; and the spacing between adjacent rows is also d; After developing with developer, the exposed SiO 2 Plasma etching is performed to expose the Si substrate; after removing the photoresist, the exposed Si is wet-etched using a NaOH solution to obtain three rows of pyramid-shaped pits with equal spacing on the Si substrate; finally, the SiO 2 obtaining a silicon template; S2, preparing a PDMS-based conductive material by mixing multi-walled carbon nanotubes, graphene and n-hexane; S3. Pour the conductive material onto the silicon template, heat and solidify it, and then peel it off from the silicon template to obtain a sensing layer of a surface pyramid multi-level ordered piezoresistive sensor.

[0008] Preferably, after step S3, the following steps are further included: S4, printing silver paste electrodes and silver paste pins on a polyethylene terephthalate (PET) film, and then heating and curing to obtain electrodes; S5, assembling the electrode obtained in S4 and the sensing layer obtained in step S3 to obtain a surface pyramid multi-level ordered piezoresistive sensor.

[0009] Preferably, the diameters of circle 1, circle 2 and circle 3 in S1 are 10 μm, 20 μm and 30 μm respectively.

[0010] Preferably, the distance between the dots is d=10 μm.

[0011] Preferably, the method of wet etching the exposed Si with a NaOH solution specifically comprises: using 6.0 M in H 2 The Si substrate was etched with NaOH solution containing 30% O for 3 h 30 min.

[0012] Preferably, the Si0 2 The film thickness is 700nm, and the exposed SiO 2 The specific process of plasma etching includes: etching power is 125W, SF 6 The etching time is 18 min and the pressure is 20 pa.

[0013] Preferably, S2 specifically includes the following steps: S2.1, after mixing multi-walled carbon nanotubes and graphene in a mass ratio of 1:1, the above mixture is mixed with n-hexane in a mass ratio of 1:20, ultrasonicated for 10 minutes and magnetically stirred for 10 minutes; S2.2, adding PDMS liquid A in a certain proportion, and magnetically stirring for 2 hours; the mass ratio of PDMS liquid A to multi-walled carbon nanotube graphene mixture is 50:3; S2.3, heat in a water bath at 75°C with stirring for 15 minutes; S2.4. Add PDMS liquid B and stir magnetically for 10 minutes to obtain a conductive material; the mass ratio of the PDMS liquid A to the PDMS liquid B is 10:1.

[0014] Preferably, S3 specifically includes the following steps: pouring the conductive material onto the silicon template, first rotating the silicon template at a speed of 500 rpm for 30 seconds, then rotating the silicon template at a speed of 1000 rpm for 60 seconds, heating the conductive film at 90°C for 10 minutes to solidify, and peeling it off from the silicon template after cooling to obtain a sensing layer of a surface pyramid multi-level ordered piezoresistive sensor.

[0015] Preferably, S4 specifically comprises the following steps: using screen printing to print 1 cm×1 cm silver paste electrodes and 3 mm×3 cm silver paste pins on a 50 μm thick polyethylene terephthalate (PET) film, and finally heating at 120°C for 20 minutes to solidify the silver paste to obtain the electrode.

[0016] The present invention also provides the sensitivity and sensing range of the silicon template after film inversion and subpackaging under different wet etching times.

[0017] In the present invention, a surface pyramid multi-level ordered piezoresistive sensor is prepared. The piezoresistive sensor includes two electrodes and a piezoresistive functional layer located between the pins, the surface of the piezoresistive functional layer is distributed with a multi-level and ordered micro-pyramid structure, and the functional layer contains multi-walled carbon nanotubes and graphene.

[0018] The piezoresistive functional layer with a multi-level ordered micro-pyramid structure proposed by the present invention changes its contact area with the electrode under the action of external force, and its internal conduction path changes, resulting in a change in internal resistance. The multi-level ordered micro-pyramid structure can well improve the sensor's dependence on electrode contact area and compressibility.

[0019] The piezoresistive functional layer of the sensor has a multi-level and ordered micro-pyramid structure. The multi-level ordered micro-pyramid structure improves the sensor's dependence on the electrode contact area and compressibility, and to a certain extent can improve the sensitivity and the sensing range of its monitoring.

[0020] The present invention also provides an application of the surface pyramid multi-level ordered piezoresistive sensor obtained by the preparation method in measuring the joint bending angle, comprising the following steps: attaching the surface pyramid multi-level ordered piezoresistive sensor to the joint, and measuring the corresponding relationship between the joint bending angle and the current; based on the corresponding relationship, inferring the joint bending angle by measuring the sensor output current.

[0021] Beneficial effects of the present invention: The present invention proposes a new three-level ordered micro-pyramid structure, and the functional layer contains multi-walled carbon nanotubes and graphene, which can be applied to sensors to improve the sensor's dependence on electrode contact area and compressibility, while improving sensitivity and sensing range; The sensing effect of the three-level ordered micro-pyramid structure proposed by the present invention is obviously better than that of similar products with one or two levels.

[0022] After encapsulating the three-level ordered micro-pyramid structure, the current change test was carried out at different finger bending angles. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a schematic diagram of the silicon template preparation process of the present invention.

[0024] Figure 2 Schematic diagram of a surface pyramid multi-level ordered piezoresistive sensor.

[0025] Figure 3 This is a schematic diagram of the microstructure of the functional layer of a surface pyramid multi-level ordered piezoresistive sensor.

[0026] Figure 4 This is the SEM image of a silicon wafer wet etched with NaOH analytical titration solution for 2h10min.

[0027] Figure 5 This is the SEM image of a silicon wafer wet etched with NaOH analytical titration solution for 2h50min.

[0028] Figure 6This is the SEM image of the silicon wafer after wet etching with NaOH analytical titration solution for 3h30min.

[0029] Figure 7 This is a detailed SEM image of the silicon wafer after wet etching with NaOH analytical solution for 2h10min.

[0030] Figure 8 This is a detailed SEM image of the silicon wafer after wet etching with NaOH analytical solution for 2h50min.

[0031] Fig. 9 This is a detailed SEM image of the silicon wafer after wet etching with NaOH analytical solution for 3h30min.

[0032] Fig.10 In the case of laser direct writing, an array with a diameter of 30μm and a spacing of 10μm is exposed on the photoresist. The wet etching time is 3h30min. The detailed SEM image after the film is inverted.

[0033] Fig.11 In the case of laser direct writing, an array of circles with diameters of 10μm and 30μm and a spacing of 10μm is cross-exposed on the photoresist. The wet etching time is 3h30min. Detailed SEM image after film inversion.

[0034] Fig.12 This is a local SEM image of the silicon wafer after wet etching with NaOH analytical solution for 2h10min.

[0035] Fig.13 This is a local SEM image of the silicon wafer after wet etching with NaOH analytical solution for 2h50min.

[0036] Fig.14 This is a local SEM image of the silicon wafer after wet etching with NaOH analytical solution for 3h30min.

[0037] Fig.15 In the case of laser direct writing, an array of circles with a diameter of 10 μm and a spacing of 10 μm is exposed on the photoresist. This is a local SEM image after the film is inverted.

[0038] Fig.16 In the case of laser direct writing, an array with a diameter of 30μm and a spacing of 10μm is exposed on the photoresist. The wet etching time is 3h30min. The local SEM image after the film is inverted.

[0039] Fig.17 In the case of laser direct writing, an array of circles with diameters of 10μm and 30μm and a spacing of 10μm is cross-exposed on the photoresist. The wet etching time is 3h30min. Local SEM image after film inversion.

[0040] Fig.18The sensitivity and sensing range of the sensor after the silicon wafer was wet-etched for 2h10min and then packaged.

[0041] Fig.19 The sensitivity and sensing range of the sensor after the silicon wafer was wet-etched for 2h50min and then packaged.

[0042] Fig. 20 The sensitivity and sensing range of the sensor after the silicon wafer was wet-etched for 3h30min and then packaged.

[0043] Fig.21 In the case of laser direct writing, an array with a diameter of 10μm and a spacing of 10μm is exposed on the photoresist, wet-etched for 2h10min, and the sensitivity and sensing range of the sensor after film inversion and packaging.

[0044] Fig. 22 When laser direct writing is used, an array with a diameter of 30μm and a spacing of 10μm is exposed on the photoresist. The wet etching time is 3h30min. The sensitivity and sensing range of the sensor after inverted film packaging.

[0045] Fig.23 In the case of laser direct writing, an array of circles with diameters of 10μm and 30μm and a spacing of 10μm is cross-exposed on the photoresist. The wet etching time is 3h30min. The sensitivity and sensing range of the sensor after inverted film packaging.

[0046] Fig.24 Current variation curves when the finger is bent at different angles for human motion detection. DETAILED DESCRIPTION Example

[0047] S1. Preparation of silicon template Schematic diagram of the silicon template preparation process Figure 1 As shown; S1.1. Using electron beam evaporation, deposit a layer of SiO on a clean Si substrate. 2 Thin film; Si substrate is crystal oriented <100> Silicon wafer, Si0 2 The film thickness is 700nm; S1.2, in uniform SiO 2 Spin-coat a layer of photoresist on the photoresist, expose circles of different diameters and evenly arranged on the photoresist, and then use developer to develop: The positive photoresist was spin coated on the SiO2 substrate at 1000 rpm for 30 s and 4000 rpm for 60 s. 2 superior; The photoresist layer is exposed with a plurality of groups of dots, each group consisting of three rows of dots arranged in parallel; the number of dots in each row is not less than three; The dots of three diameters are named circle one, circle two, and circle three from small to large in diameter, and the three rows of dots are composed of circle one, circle two, and circle three in sequence; For any row of the three dots, the spacing between the dots is fixed, denoted by d; and the spacing between adjacent rows is also d; The diameters of circle 1, circle 2, and circle 3 are 10 μm, 20 μm, and 30 μm, respectively, and the spacing is d = 10 μm. After the exposure is completed, the silicon wafer is placed in a developer for 1 minute for development. S1.3, expose SiO 2 Plasma etching was performed; the etching power was 125W, SF 6 The etching time is 18 min and the pressure is 20 pa. S1.4, wash off the photoresist with isopropyl alcohol; S1.5, use 6.0M in H 2 The exposed Si was wet-etched with NaOH analytical titration solution of O for 2h10min to obtain a cone-shaped structure with a depth of 5μm. Figure 4 As shown; S1.6, use HF to 2 Wash off; S2. Preparation of conductive materials S2.1, after mixing multi-walled carbon nanotubes and graphene in a mass ratio of 1:1, the above mixture is mixed with n-hexane in a mass ratio of 1:20, ultrasonicated for 10 minutes and magnetically stirred for 10 minutes; S2.2, adding PDMS liquid A in a certain proportion, and magnetically stirring for 2 hours; the mass ratio of PDMS liquid A to multi-walled carbon nanotube graphene mixture is 50:3; S2.3, heat in a water bath at 75°C with stirring for 15 minutes; S2.4. Add PDMS liquid B and stir magnetically for 10 minutes. The ratio of PDMS liquid A to liquid B is 10:1. S3, pour the conductive material onto the silicon template with different wet etching time, rotate at 500 rpm for 30 s and 1000 rpm for 60 s, heat the conductive film at 90 ° C for 10 minutes to solidify, and peel it from the silicon template after cooling to obtain the detailed SEM of the cone with a height of 5 μm. Figure 7 As shown, the local SEM Fig.12 shown.

[0048] S4. Electrode preparation: 1 cm × 1 cm silver paste electrodes and 3 mm × 3 cm silver paste pins were printed on a 50 μm thick polyethylene terephthalate (PET) film by screen printing, and then heated at 120 °C for 20 min to cure the silver paste.

[0049] S5. Assemble the flexible pressure sensing unit, stick the sensing layer with microstructure on the surface and the electrode together with tape, and complete the preparation of the surface pyramid multi-level ordered piezoresistive sensor. The schematic diagram is shown in Figure 2 shown.

[0050] The assembled sensor is tested for sensitivity and sensing range. The final results are as follows: Fig.18 shown. Example

[0051] The difference from Example 1 is that the exposed Si is wet-etched with NaOH solution for 2h50min to obtain a cone-shaped structure with a depth of 10μm. Figure 5 As shown; the etched silicon wafer was inverted to obtain a 10μm high cone detail SEM as shown Figure 8 As shown, the local SEM Fig.13 The assembled sensor was tested for sensitivity and sensing range, and the final results are shown in Fig.19 shown. Example

[0052] The difference from Example 1 is that the exposed Si is wet-etched with NaOH solution for 3h30min to obtain a cone-shaped structure with a depth of 15μm. Figure 6 As shown; the etched silicon wafer was inverted to obtain a 15μm high cone detail SEM as shown Fig. 9 As shown, the local SEM Fig.14 The assembled sensor was tested for sensitivity and sensing range, and the final results are shown in Fig. 20 shown. Example

[0053] The difference from Example 1 is that the array of circles with a diameter of 10 μm and a spacing of 10 μm is exposed on the photoresist, and the single-stage cone after etching is as follows: Fig.15 The sensitivity and sensing range of the assembled sensor were tested, and the final results are shown in Fig.21 shown. Example

[0054] The difference from Example 1 is that the array with a diameter of 30 μm and a spacing of 10 μm is exposed on the photoresist, and the wet etching time is 3 hours and 30 minutes. Fig.10 As shown, the local SEM Fig.16 The sensitivity and sensing range of the assembled sensor were tested, and the final results are shown in Fig. 22 shown. Example

[0055] The difference from Example 1 is that the array of circles with diameters of 10 μm and 30 μm and a spacing of 10 μm is cross-exposed on the photoresist, the wet etching time is 3 h 30 min, and the double-stage cone after the film is inverted is as follows Fig.11 As shown, the local SEM Fig.17 The sensitivity and sensing range of the assembled sensor were tested, and the final results are shown in Fig.23 shown.

[0056] like Fig.18 , 19 As shown in the figure, when the Si wet etching time is short, the microstructure presents a pillar shape after the film is inverted. Because the top of the pillar shape is large, the contact area between its functional layer and the electrode is limited, resulting in low sensitivity.

[0057] like Fig.21 As shown in the figure, when the size of the laser direct writing is 10μm and the microstructure on the functional layer is single-level, after the film is inverted, due to its low cone height and small deformation, its test range is narrow and can only test the sensitivity under 0-300kPa pressure. Fig. 22 As shown in the figure, when the size of the laser direct writing is 30μm and the microstructure on the functional layer is single-level, after the film is inverted, the microstructure of the functional layer has a certain height that can test the sensitivity under 0-800kPa pressure, but the sensitivity is small. Fig.23 As shown, when the size of the laser direct writing is 10μm and 30μm and the microstructure on the functional layer is double-level, after the film is inverted, due to the large final relative height difference, the test results are unstable and the linearity is poor.

[0058] like Fig. 20 As shown in the figure, the sensitivity of the sensor changes differently under different pressures. The overall current change rate has experienced a process of rapid increase to slow and gentle. Under 0-300kPa pressure, the sensitivity is 6.93kPa -1 , the micro-pyramid structure gradually deforms and has a certain degree of deformation capacity. Under a pressure of 325-525kPa, the deformation of the micro-pyramid structure gradually reaches saturation, with a sensitivity of 1.53kPa -1 , significantly reduced. Under 550-800kPa pressure, the microstructure deformation reaches the limit, almost no deformation, and the sensitivity is 0.233kPa -1 Whether in terms of sensitivity, test range or linearity, the functional layer microstructure with a three-level microstructure is superior to other structures. Example

[0059] The surface pyramid multi-level ordered piezoresistive sensor prepared by the above preparation method is attached to the finger joint, and the current signal output by the sensor is collected when the finger is bent at 0°, 30°, 45°, 90°, and 120°, and the corresponding relationship between the finger bending angle and the current is obtained; based on the corresponding relationship, the finger bending angle is inferred by measuring the current output by the sensor. Fig.24 As shown, the sensor output current changes significantly at different bending angles.

[0060] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present application shall be included in the scope of protection of the present application.

Claims

1. A method for preparing a surface pyramid multi-level ordered piezoresistive sensor, characterized in that: The following steps are involved: S1. Obtain a Si substrate with a SiO2 film on its surface, wherein the crystal orientation of the Si substrate is <100> ; The surface of the SiO2 film is covered with a photoresist layer, and a plurality of groups of dots are exposed on the photoresist layer, each group is composed of three rows of dots arranged in parallel; the number of dots in each row is not less than 3; The dots of three diameters are named circle one, circle two, and circle three from small to large in diameter, and the three rows of dots are composed of circle one, circle two, and circle three in sequence, and are named row one, row two, and row three respectively; The distance between circles 1, 2 and 3 in each row is fixed, denoted as d; and the distance between adjacent rows is also d; After developing with a developer, the exposed SiO2 is plasma etched to expose the Si substrate; After removing the photoresist, the exposed Si is wet-etched with a NaOH solution to obtain three rows of pyramid-shaped pits with equal spacing on the Si substrate; finally, the SiO2 is removed to obtain a silicon template; S2, preparing a PDMS-based conductive material by mixing multi-walled carbon nanotubes, graphene and n-hexane; S3. Pour the conductive material onto the silicon template, heat and solidify it, and then peel it off from the silicon template to obtain a sensing layer of a surface pyramid multi-level ordered piezoresistive sensor.

2. The method for preparing a surface pyramid multi-level ordered piezoresistive sensor according to claim 1, characterized in that: After step S3, the method further includes the following steps: S4, printing silver paste electrodes and silver paste pins on a polyethylene terephthalate (PET) film, and then heating and curing to obtain electrodes; S5. Assemble the electrode obtained in S4 and the sensing layer obtained in step S3 to obtain a surface pyramid multi-level ordered piezoresistive sensor.

3. The method for preparing a surface pyramid multi-level ordered piezoresistive sensor according to claim 1, characterized in that: The diameters of circle 1, circle 2 and circle 3 in S1 are 10 μm, 20 μm and 30 μm respectively.

4. The method for preparing a surface pyramid multi-level ordered piezoresistive sensor according to claim 3, characterized in that: The distance between the three circles is d=10 μm.

5. The method for preparing a surface pyramid multi-level ordered piezoresistive sensor according to claim 4, characterized in that: The wet etching of the exposed Si using the NaOH solution specifically includes: etching the Si substrate with a 6.0M NaOH solution for 3 hours and 30 minutes.

6. The method for preparing a surface pyramid multi-level ordered piezoresistive sensor according to claim 5, characterized in that: The thickness of the SiO2 film is 700nm, and the specific process of plasma etching the exposed SiO2 includes: etching power of 125W, SF6 of 65SCCM, pressure of 20Pa, and etching time of 18min.

7. The method for preparing a surface pyramid multi-level ordered piezoresistive sensor according to claim 5, characterized in that: S2 specifically includes the following steps: S2.1, after mixing multi-walled carbon nanotubes and graphene in a mass ratio of 1:1, the above mixture is mixed with n-hexane in a mass ratio of 1:20, ultrasonicated for 10 minutes and magnetically stirred for 10 minutes; S2.2, adding PDMS liquid A in a certain proportion, and magnetically stirring for 2 hours; the mass ratio of PDMS liquid A to multi-walled carbon nanotube graphene mixture is 50:3; S2.3, heat in a water bath at 75°C with stirring for 15 minutes; S2.

4. Add PDMS liquid B and stir magnetically for 10 minutes to obtain a conductive material; the mass ratio of the PDMS liquid A to the PDMS liquid B is 10:

1.

8. The method for preparing a surface pyramid multi-level ordered piezoresistive sensor according to claim 5, characterized in that: S3 specifically includes the following steps: pouring the conductive material onto the silicon template, rotating the silicon template at a speed of 500 rpm for 30 seconds, and then rotating the silicon template at a speed of 1000 rpm for 60 seconds, heating the conductive film at 90°C for 10 minutes to solidify it, and peeling it off from the silicon template after cooling to obtain the sensing layer of the surface pyramid multi-level ordered piezoresistive sensor.

9. The method for preparing a surface pyramid multi-level ordered piezoresistive sensor according to claim 2, characterized in that: S4 specifically includes the following steps: using screen printing to print 1 cm×1 cm silver paste electrodes and 3 mm×3 cm silver paste pins on a 50 μm thick polyethylene terephthalate (PET) film, and finally heating at 120°C for 20 minutes to solidify the silver paste to obtain the electrode.

10. Application of the surface pyramid multi-level ordered piezoresistive sensor prepared by the preparation method according to any one of claims 1 to 9 in measuring joint bending angle, characterized in that: The method comprises the following steps: attaching a surface pyramid multi-level ordered piezoresistive sensor to a joint to measure the corresponding relationship between the joint bending angle and the current; Based on the corresponding relationship, the joint bending angle is inferred by measuring the sensor output current.

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