A multimodal capacitive sensor for spatial positioning and pressure sensing and its fabrication method

Abstract

This invention belongs to the field of flexible electronic device technology, and provides a multimodal capacitive sensor for spatial positioning and pressure sensing, as well as its fabrication method. The sensor comprises, from top to bottom, an upper electrode, a flexible substrate film, an intermediate dielectric layer, and a lower electrode. The upper electrode employs a patterned design including solid and hollow regions. The edge electric field effect generated by the pores in the hollow regions creates a differentiated electric field on the sensor surface, thereby achieving spatial position recognition. The intermediate dielectric layer is a silicone elastomer composite layer doped with multi-walled carbon nanotubes, and its surface has a micropillar array. High-sensitivity contact pressure monitoring is achieved through the compression deformation of the microstructure. This invention eliminates the need for complex decoupling algorithms and arrayed structures, enabling seamless multimodal monitoring of spatial positioning and contact pressure within a single sensing unit. It has broad application prospects in intelligent robot grasping, human-computer interaction, and wearable devices.

Description

Technical Field

[0001] This invention belongs to the field of flexible electronic device technology, specifically relating to a multimodal capacitive sensor for spatial positioning and pressure sensing and its fabrication method. Background Technology

[0002] Flexible tactile sensors, as a key interface for machines to interact with the external world, can convert physical stimuli into electrical signals, thereby enabling precise perception and feedback of environmental information. Thanks to this capability, they are playing an increasingly important role in cutting-edge fields such as intelligent robots, bionic prosthetics, smart homes, and wearable devices.

[0003] However, traditional tactile sensing technology has inherent limitations, namely, it relies strictly on direct physical contact with the target object to generate feedback. This greatly diminishes its application value in non-contact and predictive scenarios. Especially in dynamic processes such as human-machine collaboration, this single contact-based sensing often leads to information lag, resulting in unstable grasping by robotic arms or increasing the risk of objects falling off.

[0004] To overcome this deficiency, several proximity-tactile multimodal sensors based on piezoresistive, triboelectric, or capacitive principles have emerged in recent years. However, existing technologies generally suffer from cumbersome structures: on the one hand, most solutions rely on electrode array designs to achieve spatial position resolution, resulting in complex device structures and difficulties in signal decoupling; on the other hand, some designs employ stacked structures with multiple independent functional layers, which not only increases the complexity of the fabrication process but also makes it difficult to simultaneously achieve high-sensitivity contact pressure sensing and spatial position recognition within a single miniature sensing unit.

[0005] Therefore, how to achieve multimodal fusion of proximity sensing, pressure monitoring and spatial positioning within a single flexible sensing unit through joint innovation of materials and structures is a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0006] To address the problems existing in the background technology, this invention proposes a multimodal flexible capacitive sensor for spatial positioning and pressure sensing, as well as its fabrication method. Through the combined effect of the differentiated edge electric field effect brought about by specially designed fabric electrodes and the dielectric layer of the deformable microstructure, the sensor is endowed with the outstanding ability to detect spatial position and contact pressure signals within a single sensing unit.

[0007] A multimodal capacitive sensor for spatial positioning and pressure sensing includes: The structure consists of an upper electrode, a flexible substrate film, a middle dielectric layer, and a lower electrode, arranged sequentially from top to bottom. The upper electrode is used to generate a differentially distributed edge electric field effect on the surface of the capacitive sensor, including solid regions and hollow regions. The dielectric layer is a flexible composite layer doped with multi-walled carbon nanotubes, and its upper surface has a microstructure array. The lower electrode forms a bonding portion with the lower surface of the intermediate dielectric layer; The flexible substrate film covers the microstructure array; The upper electrode is attached to the upper surface of the flexible substrate film.

[0008] Further optimization involves the upper electrode being a conductive layer with a preset geometric shape, and the ratio of the solid area to the hollow area of ​​the upper electrode being 1:1.

[0009] Further optimization involves selecting the shape of the preset geometric conductive layer from one of the following: square, rectangular, circular, spiral, or petal-shaped; and the hollowed-out area is a hollowed-out structure formed by cutting out the interior of the upper electrode.

[0010] Further optimization involves the flexible composite of the intermediate dielectric layer also including a silicone elastomer.

[0011] Further optimization is achieved by setting the mass ratio of the multi-walled carbon nanotubes to the silicone elastomer to be 0.5-2%.

[0012] Further optimization involves the microstructure array being a cylindrical micropillar array, with the cylinder having a height of 0.7~0.8mm and a diameter of 1~3mm.

[0013] Further optimization involves using conductive silver tape for both the upper and lower electrodes, a PET film for the flexible substrate, and encapsulating the sensor with PI insulating tape.

[0014] A method for fabricating a multimodal capacitive sensor for spatial positioning and pressure sensing includes the following steps: S1. A three-dimensional model of the intermediate dielectric layer is created and a rigid resin mold with a microstructure array is prepared using photopolymerization 3D printing technology. S2. The flexible polymer matrix is ​​mixed with multi-walled carbon nanotubes and then poured into the rigid resin mold. After heating and curing, it is peeled off to obtain an intermediate dielectric layer with a microstructure array on one side. S3. Cut the conductive material into a lower electrode and an upper electrode, wherein the upper electrode includes a solid area and a hollow area; S4. Attach the lower electrode to the lower surface of the intermediate dielectric layer, cover the upper surface of the microstructure array with a flexible substrate film, attach the upper electrode to the top surface of the flexible substrate film, connect the wires, and encapsulate to obtain the sensor.

[0015] Further optimization: In step S2, the flexible polymer matrix is ​​Ecoflex, which includes component A and component B, wherein the mass ratio of component A to component B is (3~4):1.

[0016] Further optimization is made to the heating and curing process in step S2, which is to cure at 60~80℃ for 0.8~1.2h.

[0017] The technical solution of the present invention achieves the following beneficial technical effects: 1. Based on electrode patterning design, multimodal sensing and spatial positioning are realized within a single sensing unit. Current sensors employ a single solid structure for their upper electrode without regional differentiation, resulting in insufficient precision in sensing and spatial positioning. This invention addresses this issue by using a patterned structure combining solid and hollow areas for the upper electrode. The hollow areas, due to their internal pores, significantly extend the effective edge length of the electrode, generating a stronger edge electric field effect. In contrast, the solid areas primarily exhibit parallel-plate capacitance, leading to uneven edge electric field distribution. When a target object approaches or contacts the sensor surface, the solid and hollow areas display distinctly different capacitive response characteristics. This differentiated signal, obtainable from a single electrode layer, eliminates the need for complex array structures or multi-layer decoupling designs. It enables simultaneous proximity sensing, pressure monitoring, and spatial location recognition within the same sensing unit, greatly simplifying device structure and reducing signal processing complexity.

[0018] 2. Based on the differences in material conductivity, non-contact conductive property differentiation is achieved. When different materials approach the sensor surface, their varying conductivity results in different ways and degrees of disturbance to the sensor's edge electric field. Conductors, in particular, induce more significant electric field changes, leading to a larger capacitive response; while insulating materials have a relatively weaker impact on the edge electric field, and their output signal amplitude and near-field response differ significantly from those of conductors. Utilizing this characteristic, the designed sensor can distinguish the conductivity properties of different materials in a non-contact state, providing a basis for material classification.

[0019] 3. Achieving high-sensitivity pressure sensing based on the synergistic design of dielectric layer materials and microstructures. This invention incorporates multi-walled carbon nanotubes (0.5-2% by weight of the silicone elastomer) into the intermediate dielectric layer, effectively enhancing the dielectric constant of the composite material and thus improving its capacitive response sensitivity under pressure. Simultaneously, the micropillar array on the dielectric layer surface undergoes controllable compressive deformation under pressure, further amplifying the capacitance change signal. The synergistic effect of material modification and microstructure design results in a significant increase in sensor sensitivity within the low-pressure range, approximately 44 times higher than that of undoped devices.

[0020] 4. Achieve reliable molding and low-cost fabrication of microstructures based on process optimization. To address the issue that hydroxyl groups on the surface of photocurable resin molds may interfere with the curing of silicone elastomers, this invention employs a specific ratio of Ecoflex A / B components, effectively overcoming the defects of incomplete curing or incomplete molding at the interface, ensuring the complete molding of the micropillar array. This method combines material modification with process optimization, has a simple process flow, readily available raw materials, and good potential for large-scale mass production. Attached Figure Description

[0021] Figure 1 The figure shows an overall structural schematic diagram of the multimodal flexible capacitive sensor described in the embodiment and a planar pattern schematic diagram of the upper electrode. The reference numerals in the figure are: 1. Upper electrode, 2. Flexible substrate film, 3. Intermediate dielectric layer, 4. Lower electrode. Figure 2 This is a schematic diagram of the effective conductive border of the hollowed-out area of ​​the upper electrode structure of the multimodal flexible capacitive sensor in the embodiment. Figure 3 This is a comparison curve of the pressure sensing performance of the capacitive sensor in the embodiment when doped with multi-walled carbon nanotubes of different mass fractions. Figure 4 This is a comparison diagram of the dynamic capacitance response of the capacitance sensor in the embodiment when objects of different materials approach each other; Figure 5 The sensitivity performance curves of the capacitive sensor in the embodiment under proximity sensing and contact pressure sensing modes are shown. Figure 6 A comparison diagram of the capacitance response differences of the capacitive sensor in the embodiment as the proximity distance changes at different detection positions (directly above the solid area and the hollow area of ​​the upper electrode). Figure 7 A comparison of the dynamic capacitance response of the capacitive sensor used in this embodiment when it laterally scans across different electrode regions at multiple different hovering heights; Figure 8 An experimental device for dynamic grasping of a mechanical gripper equipped with a capacitive sensor according to an embodiment; Figure 9 The capacitive sensor used in this embodiment provides a signal feedback diagram for seamless monitoring of non-contact proximity and contact pressure in a dynamic grasping scenario using a robotic gripper. Figure 10 Comparison curves were generated to test the proximity sensing performance of the capacitive sensors in Examples 1-4. Detailed Implementation Example

[0022] This embodiment provides a multimodal capacitive sensor for spatial positioning and pressure sensing, comprising an upper electrode 1, a flexible substrate film 2, an intermediate dielectric layer 3, and a lower electrode 4 (e.g., ...) stacked from top to bottom. Figure 1 ).

[0023] The upper electrode 1 is cut from conductive silver tape, and is a square conductive layer with an overall size of 10mm × 10mm. It is divided into two 5mm × 10mm halves along the center line: one half is a completely solid area, and the other half has a rectangular pattern cut out to form a hollow area. The four outer edges of the hollow area retain a conductive border with a width of 1mm, that is, the effective conductive border width b of the hollow area is 1mm (e.g., Figure 2 ).

[0024] The flexible substrate film 2 is a PET film with a size of 10mm × 10mm.

[0025] The intermediate dielectric layer 3 is composed of a silicone elastomer doped with multi-walled carbon nanotubes. Its upper surface is provided with a cylindrical micropillar array, with a micropillar diameter of 1 mm and a height of 0.8 mm. The lower surface is flat, and the overall size is 10 mm × 10 mm.

[0026] The lower electrode 4 is cut from conductive silver tape and is a complete square patch of 10mm×10mm.

[0027] The lower electrode 4 is attached to the flat lower surface of the intermediate dielectric layer 3, the flexible substrate film 2 covers the micropillar array of the intermediate dielectric layer 3, and the upper electrode 1 is attached to the top surface of the flexible substrate film 2.

[0028] A method for fabricating a multimodal capacitive sensor for spatial positioning and pressure sensing includes the following steps: 1. Mold preparation A cylindrical micropillar array mold was designed using 3D modeling software. The micropillars have a diameter of 1 mm and a height of 0.8 mm. The mold was then printed into a rigid resin mold using a photopolymerization 3D printer.

[0029] 2. Preparation of intermediate dielectric layer and screening of doping concentration Components A and B of Ecoflex (manufacturer: smooth-on) were weighed and mixed uniformly at a mass ratio of 3:1 to obtain a flexible polymer matrix. To determine the optimal doping concentration of multi-walled carbon nanotubes (MWCNTs), composite slurries with MWCNT and silicone elastomer doping mass ratios of 0%, 1.0%, 1.5%, 2.0%, and 2.5% were prepared. Experiments showed that as the doping concentration increased, the contact sensitivity of the sensor gradually increased (e.g., ...). Figure 3However, when the concentration reaches 2.5%, the viscosity of the theoretical composite slurry is too high, which easily leads to a rough surface of the cured dielectric layer, defects in the micropillar array, and a significant decrease in molding quality. Considering both process feasibility and sensitivity improvement, 2.0% was ultimately selected as the optimal doping concentration. The specific operation is as follows: Take 10g of the mixed Ecoflex matrix, add 0.2g of MWCNTs with a purity of 98% (mass fraction 2.0wt%), and stir thoroughly for 3min to uniformly disperse the multi-walled carbon nanotubes in the matrix. Pour the resulting composite slurry into the rigid resin mold and place it in a vacuum chamber for degassing for 5min to remove air bubbles. Then cover the mold surface with a glass slide and apply an appropriate amount of weight for pressure, and cure on a 70°C heating stage for 1h. After cooling, peel off the mold to obtain an intermediate dielectric layer 3 with a cylindrical micropillar array on one side and a flat side on the other.

[0030] 3. Electrode fabrication and device assembly A conductive silver tape is cut into 10mm × 10mm square pieces to serve as the lower electrode 4. Another conductive silver tape is patterned using a carving tool to create a patterned upper electrode 1 with solid and hollow areas. The lower electrode 2 is attached to the flat lower surface of the intermediate dielectric layer 3. A PET film is then placed over the upper surface of the intermediate dielectric layer 3 on the side with the micropillar array. The upper electrode 1 is then adhered to the upper surface of the PET film. Copper wires are connected using epoxy resin to lead out the electrical signals from the upper electrode 1 and the lower electrode 4, respectively. Finally, PI insulating tape is wrapped around the device for omnidirectional encapsulation, thus obtaining the aforementioned multimodal capacitive sensor for spatial positioning and pressure sensing.

[0031] The above-mentioned capacitive sensors were subjected to various performance tests, including: dynamic capacitance response when objects of different materials approached each other. Figure 4 Sensitivity performance in proximity sensing and contact pressure sensing modes Figure 5 Comparison of capacitance response differences with approach distance at different detection positions (directly above the solid area and the hollow area of ​​the upper electrode 1). Figure 6 Dynamic capacitance response when laterally scanning across different electrode regions at multiple different hovering heights. Figure 7 ), and in the mechanical gripper ( Figure 8 In dynamic capture scenarios, signals are used to achieve seamless monitoring of non-contact proximity and contact pressure. Figure 9 ).

[0032] Test results show that: like Figure 4As shown, within the approach range of 0–40 mm, the capacitance response curves of different materials exhibit significant differences. Conductive materials such as 45# steel and aluminum alloy more significantly disturb the edge electric field near the sensor, resulting in larger capacitance changes. In contrast, insulating materials such as Bakelite and PLA have a weaker disturbance effect on the edge electric field, thus exhibiting smaller overall capacitance changes. Especially during the close-range approach phase, the response differences between different materials are more pronounced, demonstrating good distinguishability.

[0033] like Figure 5 As shown in Figure a, in contact mode, the sensor's relative capacitance change rate exhibits two approximately linear responses with increasing pressure. Specifically, the sensitivity is 0.123 kPa⁻¹ in the 0–10 kPa range and 0.056 kPa⁻¹ in the 11–55 kPa range. The former is mainly due to the microstructure's susceptibility to compression deformation under low pressure, while the latter is due to the gradual compaction of air gaps, resulting in a slight decrease in sensitivity, but still maintaining a good linear response.

[0034] In proximity mode, such as Figure 5 As shown in b, as the target object gradually approaches the sensor surface, the relative rate of change of capacitance generally shows a negative decreasing trend. When the distance is greater than 40 mm, the capacitance change is negligible; in the range of 5–40 mm, the distance sensitivity is −0.0063 cm⁻¹; when the target enters the near-field region of 0–5 mm, the sensitivity significantly increases to −0.14 cm⁻¹.

[0035] like Figure 6 As shown, a fixed-point vertical proximity comparison experiment was designed for different electrode regions. Figure 6 a) Using a lateral displacement platform, the ungrounded copper rod was aligned with the geometric center of both the solid and hollow areas. Then, a tensile testing machine was used to control the copper rod, suspending it at multiple specific height nodes within a range of 0–40 mm from the sensor surface. The relative capacitance change rate was recorded point by point at each discrete distance. The experimental results are as follows: Figure 6 As shown in b, at the same hovering height, the capacitance change in the hollowed-out area is generally greater than that in the solid area. This difference in response caused by the difference in the top electrode structure becomes increasingly significant as the approaching object gets closer to the sensor surface. Notably, when the approaching object gets within 1 mm, the capacitance change trend in the solid area shows a clear reversal compared to the hollowed-out area, which further amplifies the signal characteristic difference between the two areas.

[0036] like Figure 7As shown, a constant-height horizontal movement test experiment was designed. In the experiment, an ungrounded copper rod was first fixed at a specific constant height using a tensile testing machine. Figure 7 a) Subsequently, a lateral displacement platform was used to drive the sensor to translate at a constant speed, causing the copper rod to move along the centerline trajectory of the sensor, starting from one edge of the solid area, uniformly traversing the solid and hollow areas, and finally completely moving out of the other edge. The experiment set the longitudinal hovering height to 0.5mm, 3mm, and 5mm respectively, and repeated the above translation test process sequentially, showing continuous translation at different hovering heights. It can be clearly observed from the figure that when the copper rod crosses the physical boundary between the solid and hollow areas, the capacitance signal exhibits a step-like continuous change (…). Figure 7 (b) Notably, at an extremely close scanning height of 0.5 mm, the capacitance signal in the solid region showed a significant increase. Furthermore, as the set longitudinal scanning height decreased (from 5 mm to 0.5 mm), the signal difference between the solid and hollowed-out regions increased sharply, and the regional boundary characteristics of the signal became more pronounced.

[0037] like Figure 8 As shown, the sensor is integrated into the mechanical gripper system to monitor the approach and contact status of the target object in real time during the gripping process. Figure 9 a and Figure 9 b illustrates the dynamic capacitance feedback curves corresponding to different electrode regions. As the robotic gripper gradually approaches and ultimately grasps the target object, the sensor continuously outputs corresponding capacitance change signals. When the copper rod is above the solid region, the capacitance initially decreases, then increases before contact, and rises rapidly after contact. When the copper rod is above the hollow region, the capacitance continuously decreases before contact and increases rapidly after contact. This result demonstrates that the sensor of this invention can continuously monitor the entire process of a target object from non-contact approach to contact grasping, exhibiting excellent real-time response and dynamic process perception capabilities, and can be applied to complex dynamic interaction scenarios such as robotic grasping.

[0038] Comparative Example 1 This embodiment provides a multimodal capacitive sensor for spatial positioning and pressure sensing, the difference being that the upper electrode 1 is a completely hollowed-out area, with an effective conductive frame width of 2mm, and the overall outer boundary dimensions remain the same as in Embodiment 1 (10mm × 10mm). The remaining structures (lower electrode 1, intermediate dielectric layer 3, flexible substrate film 2) and preparation methods are consistent with Embodiment 1.

[0039] Comparative Example 2 This embodiment provides a multimodal capacitive sensor for spatial positioning and pressure sensing, the difference being that the upper electrode 1 is a completely hollowed-out area, its effective conductive frame width is 3mm, and the overall outer boundary size remains the same as in Embodiment 1 (10mm × 10mm). The remaining structure and fabrication method are consistent with Embodiment 1.

[0040] Comparative Example 3 This embodiment provides a multimodal capacitive sensor for spatial positioning and pressure sensing, the difference being that the upper electrode 1 is a completely hollowed-out area, its effective conductive frame width is 4mm, and the overall outer boundary size remains the same as in Embodiment 1 (10mm × 10mm). The remaining structure and fabrication method are consistent with Embodiment 1.

[0041] Comparative Example 4 This comparative example provides a multimodal capacitive sensor for spatial positioning and pressure sensing. The structure is the same as that of Example 1, except that the upper electrode 1 is solid, meaning there is no hollow area in the upper electrode, and the overall outer boundary size remains the same as that of Example 1 (10 mm × 10 mm). All other structural features are consistent with Example 1.

[0042] Experimental Example The proximity sensing performance of the capacitive sensors prepared in Comparative Examples 1-4 was tested respectively, and the test results are as follows: Figure 10 As shown, as the upper electrode gradually changes from a solid structure to a hollow narrow ring structure, the relative capacitance change rate and proximity sensitivity of the sensor at the same proximity distance gradually increase. Among them, the electrode with an effective conductive frame width of 2mm in the hollow area of ​​Example 1 has the best proximity sensing performance, which proves that the sensitivity of the hollow structure is better than that of the solid structure, and the smaller the effective frame width, the better its performance.

[0043] The reason is that after the central region of the upper electrode is hollowed out, the effective facing area of ​​the upper and lower electrodes decreases, and the initial capacitance decreases. At the same time, the proportion of the electrode edges increases, and the edge electric field is enhanced, making the capacitance change caused by the approach of the target object more obvious. Therefore, reducing the effective width of the upper hollow ring electrode is beneficial to improving the proximity sensing sensitivity of the sensor.

[0044] Based on the comparative experimental results above, the semi-solid, semi-hollow upper electrode structure used in this embodiment, through optimization of the effective conductive border width of the hollow area, enables different regions of the sensor surface to generate distinguishable capacitive response characteristics during the approach of a target object, thereby facilitating the differentiation of the target object's spatial position. Combined with... Figure 6 and Figure 7 The test results show that the structure can achieve differentiated outputs in different regions, thus providing a basis for spatial location identification of targets.

[0045] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. It will be apparent to those skilled in the art that the present invention is not limited to the details of the above exemplary embodiments, and can be implemented in other specific forms without departing from the spirit or basic characteristics of the present invention.

Claims

1. A multimodal capacitive sensor for spatial positioning and pressure sensing, comprising an upper electrode (1), a flexible substrate thin film (2), an intermediate dielectric layer (3), and a lower electrode (4) arranged sequentially from top to bottom, characterized in that, The upper electrode (1) is used to generate a differentially distributed edge electric field effect on the surface of the capacitive sensor, including solid regions and hollow regions; The intermediate dielectric layer (3) is a flexible composite layer doped with multi-walled carbon nanotubes, and its upper surface has a microstructure array. The lower electrode (4) and the lower surface of the intermediate dielectric layer (3) form a bonding portion; The flexible substrate film (2) covers the microstructure array; The upper electrode (1) is attached to the upper surface of the flexible substrate film (2).

2. The multimodal capacitive sensor for spatial positioning and pressure sensing according to claim 1, characterized in that, The upper electrode (1) is a conductive layer with a preset geometric shape, and the ratio of the solid area to the hollow area of ​​the upper electrode (1) is 1:

1.

3. A multimodal capacitive sensor for spatial positioning and pressure sensing according to claim 2, characterized in that, The shape of the preset geometric conductive layer is selected from one of square, rectangle, circle, spiral, and petal shape, and the hollow area is a hollow structure formed by cutting out the interior of the upper electrode (1).

4. A multimodal capacitive sensor for spatial positioning and pressure sensing according to claim 1, characterized in that, The flexible composite of the intermediate dielectric layer (3) also includes a silicone elastomer.

5. A multimodal capacitive sensor for spatial positioning and pressure sensing according to claim 4, characterized in that, The mass ratio of the multi-walled carbon nanotubes to the silicone elastomer is 0.5~2%.

6. A multimodal capacitive sensor for spatial positioning and pressure sensing according to claim 1, characterized in that, The microstructure array is a cylindrical micropillar array, with the cylinder having a height of 0.7~0.8mm and a diameter of 1~3mm.

7. A multimodal capacitive sensor for spatial positioning and pressure sensing according to claim 1, characterized in that, The upper electrode (1) and the lower electrode (4) are both conductive silver tapes, the flexible substrate film (2) is a PET film, and the sensor is encapsulated by PI insulating tape.

8. A method for fabricating a multimodal capacitive sensor for spatial positioning and pressure sensing as described in claims 1-7, characterized in that, Includes the following steps: S1. A three-dimensional model of the intermediate dielectric layer (3) is created and a rigid resin mold with a microstructure array is prepared using photopolymerization 3D printing technology. S2. The flexible polymer matrix is ​​mixed with multi-walled carbon nanotubes and then poured into the rigid resin mold. After heating and curing, it is peeled off to obtain an intermediate dielectric layer with a microstructure array on one side. S3. The conductive material is cut into a lower electrode (4) and an upper electrode (1), wherein the upper electrode (1) includes a solid area and a hollow area; S4. The lower electrode (4) is attached to the lower surface of the intermediate dielectric layer (3), the flexible substrate film (2) is covered on the upper surface of the microstructure array, the upper electrode (1) is attached to the top surface of the flexible substrate film, and after connecting the wires, it is packaged to obtain the sensor.

9. The preparation method according to claim 8, characterized in that, In step S2, the flexible polymer matrix is ​​Ecoflex, which includes component A and component B, wherein the mass ratio of component A to component B is (3~4):

1.

10. The preparation method according to claim 8, characterized in that, The heating and curing process in step S2 is as follows: curing at 60~80℃ for 0.8~1.2h.

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