A flexible strain sensor and method of fabricating the same

Abstract

The application discloses a kind of grouping micro column structure cloth-based flexible strain sensor and method, first liquid elastomer and conductive elastomer are scraped to the surface of conductive fabric, then it is heated and dried;Second step, the solidified liquid elastomer is processed in region with laser cutting machine, the solidified elastomer outside micro column region is cut off, and support micro column array is obtained;Third step, after the region processing of conductive elastomer with laser cutting machine, the top of conductive micro column is cut again, and control micro column array is obtained;Fourth step, the columnar head of support micro column array is immersed in adhesive, then the conductive elastomer thin layer around control micro column array is pressed tightly from top to bottom, and is bonded, waits for adhesive to be completely solidified, and grouping micro column structure cloth-based flexible strain sensor is obtained.The method has very important practical value and innovative significance for the rapid preparation and integration of flexible strain sensor with adjustable sensitivity, adjustable strain range and comfortable wearing.

Description

Technical Field

[0001] This invention belongs to the field of biomedical electrotechnology, specifically relating to a grouped micropillar structure cloth-based flexible strain sensor and method. Background Technology

[0002] In recent years, with the development of the metaverse, human posture recognition has attracted widespread attention. Compared with traditional human posture recognition methods such as visual cameras, flexible strain sensors are not only more accurate but also easier to integrate with clothing for seamless wear, making them highly promising for applications in human-computer interaction, health monitoring, and gesture recognition. However, the different joint flexibility and bending angles corresponding to posture changes in different parts of the human body place higher demands on the sensitivity and adjustable strain range of flexible strain sensors.

[0003] Flexible polymer substrates offer excellent machinability and are currently the mainstream solution for realizing flexible strain sensors. To convert deformation into electrical quantities such as resistance and capacitance, methods typically involve filling the flexible polymer with conductive fillers such as single-walled carbon nanotubes, or printing conductive silver paste or other metallic polymer conductors onto the flexible polymer surface. However, flexible strain sensors based on flexible polymer substrates are usually applied directly to the skin, which does not meet people's daily wearing habits, resulting in poor comfort, adaptability, and reusability. Therefore, developing fabrication methods for flexible strain sensors with adjustable sensitivity and strain range based on fabric substrates is of great significance.

[0004] A search of existing technologies revealed that Conor J. Walsh et al. from the Wyss Institute at Harvard University published an article in Advanced Materials Technologies, 2017, 2(9):1700136 entitled "Batch Fabrication of Customizable Silicone-Textile Composite Capacitive Strain Sensors for Human Motion Tracking." This article describes a design and mass production method for a textile-based silicone capacitive flexible strain sensor, using conductive knitted fabric as electrodes and silicone elastomer as the dielectric, based on a sandwich-like structure. The fabricated flexible strain sensor exhibits high linearity and low hysteresis. However, this capacitive flexible strain sensor has a small strain detection range and its sensitivity is not adjustable, making it challenging to detect full-body posture changes and adapt to different user needs.

[0005] Helen Tran, Xinyu Liu, and colleagues from the University of Toronto, Canada, published an article in *Nature Communications*, 2023, 14(1):623, entitled "Conductive and elastic bottlebrush elastomers for ultrasoft electronics," developing a solvent-free, ultrasoft, and conductive PDMS elastomer (BBE) composite material using single-walled carbon nanotubes (SWCNTs) as the conductive filler. The conductive SWCNT / BBE with a filler concentration of 0.4–0.6 wt% exhibits an ultralow Young's modulus (<11 kPa) and conductivity greater than 2 S / m, while maintaining adhesion. Furthermore, based on this conductive and non-conductive BBE, a flexible strain sensor was fabricated using laser cutting and 3D printing, demonstrating its potential applications in wearable sensing, soft robotics, and electrophysiological recording. However, this method of direct application to the skin surface does not conform to normal human wearing habits and has a certain impact on posture and movement, making it impossible to integrate into fabric for seamless wear.

[0006] CN113237419A discloses a high-sensitivity flexible capacitive strain sensor and its fabrication method. The sensor comprises five layers: a first tensile structural layer, an upper electrode plate, a porous dielectric layer, a lower electrode plate, and a second tensile structural layer. The flexible substrate is made of silicone rubber (Ecoflex) or hydrogel. Stretching the tensile structural layers increases the deformation of the capacitor structure area, thereby improving the sensitivity of the flexible capacitive strain sensor. However, this type of flexible capacitive strain sensor has a limited strain detection range and cannot be flexibly adjusted, making it unsuitable for detecting strains with large ranges, such as those experienced by wrists or elbows.

[0007] CN113670187A discloses a capacitive elastic strain sensor and its fabrication method that combine high safety with a long detection range. The sensor comprises a matrix made of elastic textile material, an elastic adhesive layer, a first conductive layer, an elastic dielectric layer, and a second conductive layer, improving safety protection while effectively widening the detectable stress range. However, the range of this type of capacitive strain sensor cannot be freely adjusted, and its deformation range is limited. When the external stress is large, the actual deformation of the sensor exceeds the upper limit, leading to inaccurate detection and reduced sensitivity; when the external stress is small, the actual deformation of the sensor is below the lower limit, and the sensor will be unable to detect the stress.

[0008] Therefore, the rapid fabrication and integration of flexible strain sensors with adjustable sensitivity, adjustable strain range, and comfortable wearability to capture the curvature of human joints and reconstruct human posture has significant practical value and innovative implications. This approach can effectively address the current challenges of rapid mass production of flexible strain sensors, the difficulty in freely adjusting sensitivity and strain limits, and the lack of practicality. Summary of the Invention

[0009] To overcome the shortcomings of existing technologies, this invention provides a flexible strain sensor based on a grouped micropillar structure and its method. The first step involves coating a liquid elastic material and a conductive elastic material onto the surface of a conductive fabric, followed by heating and drying to allow both materials to solidify. During this process, the two elastic materials partially penetrate the conductive fabric, which helps improve interfacial strength. The second step uses a laser cutter to process the solidified liquid elastic material in specific areas, cutting away the solidified elastic material outside the micropillar area to obtain a supporting micropillar array. The third step involves processing the conductive elastic material in specific areas using a laser cutter, followed by a fixed-depth cut at the top of the conductive micropillars to obtain a controllable micropillar array. The fourth step involves immersing the columnar heads of the supporting micropillar array into an adhesive, then pressing them together from top to bottom with thin layers of conductive elastic material surrounding the controllable micropillar array to bond them. After the adhesive has fully cured, the flexible strain sensor based on the grouped micropillar structure is obtained. This method has significant practical value and innovative implications for the rapid fabrication and integration of flexible strain sensors with adjustable sensitivity, adjustable strain range, and comfortable wearability, enabling the capture of human joint curvature and the reconstruction of human posture. It can effectively solve the problem that current flexible strain sensors of the same type cannot simultaneously detect large and small strains of human joints to achieve whole-body posture recognition.

[0010] The technical solution adopted by this invention to solve its technical problem is as follows:

[0011] A flexible strain sensor based on a grouped micropillar structure includes a top conductive layer 1, a supporting micropillar array 2, a regulating micropillar array 3, and a bottom conductive layer 5.

[0012] Both the top conductive layer 1 and the bottom conductive layer 5 are conductive fabrics; the conductive fabrics are made of cloth combined with metal polymer conductors or metal particles.

[0013] The supporting micropillar array 2 uses an elastic material as a substrate and includes a supporting micropillar base and multiple supporting micropillars; the supporting micropillar base is attached to the top conductive layer 1; the supporting micropillar is columnar, with one end integrated with the supporting micropillar base;

[0014] The control micropillar array 3 uses a conductive elastic material as a substrate and includes a control micropillar base and multiple control micropillars; the control micropillar base is attached to the bottom conductive layer 5; the control micropillar is columnar, with one end integrated with the control micropillar base and the other end suspended; the multiple control micropillars have different heights and are arranged in a stepped manner.

[0015] The other end of the supporting micropillar contacts the control micropillar base and is bonded together with an adhesive.

[0016] Preferably, the conductive fabric is made by combining ordinary fabric with metal polymer conductors or metal particles through electrolytic plating, metal coating, or metal cladding.

[0017] Preferably, the elastic material is polydimethylsiloxane (PDMS), polyurethane (TPU), polyvinylidene fluoride (PVDF), or polynaphthalene ester (PEN).

[0018] Preferably, the conductive elastic material is polydimethylsiloxane (PDMS), polyurethane (TPU), polyvinylidene fluoride (PVDF), or polynatyl ester (PEN) elastic material, and its conductivity is achieved by doping with carbon nanotubes, carbon black, liquid metal, or conductive polymers.

[0019] Preferably, the supporting micropillars are cylinders with a height of 4 to 7 mm and a diameter of 1 mm, and the supporting micropillars are spaced 1 to 2 mm apart.

[0020] Preferably, the control micropillars are cylinders with a diameter of 2-3 mm, the spacing between the control micropillars is 2-3 mm, and the height difference between the control micropillars is 1-2 mm.

[0021] A method for fabricating a grouped micropillar structure cloth-based flexible strain sensor, the specific steps of which are as follows:

[0022] Step 1: Immerse the knitted cotton fabric in a dispersion of liquid metal and ethanol, wait for the dispersion to completely saturate the knitted cotton fabric, and then place it in an oven to heat and solidify, thus obtaining a conductive fabric;

[0023] Step 2: Take two pieces of conductive fabric as the top conductive layer 1 and the bottom conductive layer 5 respectively; apply liquid elastic material to the surface of the top conductive layer 1 and liquid conductive elastic material to the surface of the bottom conductive layer 5, so that the elastic material and conductive elastic material penetrate into the conductive fabric and are completely cured.

[0024] Step 3: Use a laser to cut the elastic material cured on the top conductive layer 1 to obtain the supporting micropillar array 2; use a laser to cut the conductive elastic material cured on the bottom conductive layer 5 to obtain the transition micropillar array of equal height; then cut the top of the transition micropillar array to obtain the control micropillar array 3 with a height stepped arrangement.

[0025] Step 4: Immerse the support micropillar array 2 half into the adhesive, ensuring that the lower half of each support micropillar is wrapped with adhesive;

[0026] Step 5: Align the support micropillar array 2, which is wrapped with adhesive, with the gap of the control micropillar array 3, so that the support micropillar array 2 contacts the control micropillar base and is then pressed downwards; then, place the whole assembly in an oven to dry and heat until the adhesive is completely cured and bonded, thus obtaining a grouped micropillar structure cloth-based flexible strain sensor.

[0027] Preferably, the conductive fabric is obtained by dispersing liquid metals of sodium and gallium in an ethanol at a mass ratio of 3:1, then completely immersing knitted cotton fabric in the dispersion, waiting for 30 minutes until the dispersion has completely penetrated the knitted cotton fabric, and then placing it in an oven to be heated and dried at 80 degrees Celsius for 2 hours.

[0028] The beneficial effects of this invention are as follows:

[0029] Existing research largely focuses on the basic materials of flexible strain sensors, aiming to improve their performance through material optimization. However, methods for controlling the sensitivity and strain detection range of flexible strain sensors through structural and process design are lacking. Traditional flexible strain sensors have limited ranges and cannot be freely adjusted. Furthermore, direct application to the skin does not conform to normal wearing habits, affecting posture and movement, and cannot be integrated into fabrics. To address this issue, this invention proposes a laser processing method for a grouped micropillar structure fabric-based flexible strain sensor. Through laser depth-controlled cutting, a support micropillar array based on elastic materials and a control micropillar array based on conductive elastic materials are obtained, allowing for the control of the stress detection upper limit and sensitivity, effectively solving the problem of the current flexible strain sensor's inability to freely adjust the detection range and sensitivity. Simultaneously, this grouped micropillar structure fabric-based flexible strain sensor, based on conductive-treated knitted cotton fabric, can be integrated with ordinary clothing fabrics, better conforming to normal wearing habits. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the structure of the grouped micropillar structure cloth-based flexible strain sensor of the present invention.

[0031] Figure 2 This is a flowchart illustrating the fabrication process of the grouped micropillar structure cloth-based flexible strain sensor of the present invention.

[0032] Figure 3 This is a schematic diagram illustrating the working mechanism of the grouped micropillar structure cloth-based flexible strain sensor of the present invention.

[0033] Figure 4 This is a variant diagram of the controllable micropillar array structure of the grouped micropillar structure cloth-based flexible strain sensor according to an embodiment of the present invention.

[0034] Figure 5 This is a variant diagram of the supporting micropillar array structure of the grouped micropillar structure cloth-based flexible strain sensor according to an embodiment of the present invention.

[0035] The diagram shows: 1. Top conductive layer; 2. Supporting micropillar array; 3. Controlling micropillar array; 4. Adhesive; 5. Bottom conductive layer. Detailed Implementation

[0036] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0037] This invention provides a grouped micropillar structure cloth-based flexible strain sensor and a laser processing method, which can flexibly adjust the sensitivity and strain upper limit, while achieving high interface reliability, and can be rapidly and in batches for fabrication and integration.

[0038] The processing method involves four parts: a top conductive layer, a bottom conductive layer, a supporting micropillar array, and a regulating micropillar array. The top and bottom conductive layers are conductive fabrics, which are made by combining ordinary fabrics with metal polymer conductors or metal particles through methods such as electrolytic plating, metal coating, and metal cladding.

[0039] The supporting micropillar array uses elastic materials such as polydimethylsiloxane (PDMS), polyurethane (TPU), polyvinylidene fluoride (PVDF), or polynaphthalene ester (PEN) as a substrate. It is formed by laser cutting away the area outside the micropillars from the substrate. The diameter, height, and spacing of the micropillars are determined by the substrate thickness and laser cutting parameters.

[0040] The controlled micropillar array uses elastic materials such as polydimethylsiloxane (PDMS), polyurethane (TPU), polyvinylidene fluoride (PVDF), or polynatyl ester (PEN), and is doped with conductive fillers such as carbon nanotubes, carbon black, liquid metal, or conductive polymers as a substrate. It is formed by laser cutting away the area outside the micropillars from the substrate. The diameter, height, and spacing of the micropillars are determined by the substrate thickness and laser cutting parameters, while the conductivity of the micropillars is determined by the type and concentration of the conductive filler used.

[0041] The supporting micropillar array provides structural strength; the wider the diameter of the supporting micropillars and the denser the array, the greater the structural strength and the higher the upper limit of the detectable stress. Adjusting the micropillar array provides conductivity; the closer the conductivity of the micropillars is to that of a semiconductor, and the larger the array height range and the more gradients, the higher the detection sensitivity.

[0042] The overall size of the cloth-based flexible strain sensor is determined by the size and shape of the attachment area. A large-area cloth-based flexible strain sensor can be prepared first, and then the required pattern can be customized by a laser cutting machine.

[0043] The laser processing steps for the grouped micropillar structure cloth-based flexible strain sensor are as follows:

[0044] Step 1: Immerse the knitted cotton fabric in a dispersion of liquid metal and ethanol, wait for the dispersion to completely saturate the knitted cotton fabric, and then place it in an oven to heat and solidify, thus obtaining a conductive fabric.

[0045] Step 2: Apply liquid elastic material to the surface of the conductive fabric (top conductive layer) and apply conductive liquid elastic material to the surface of the conductive fabric (bottom conductive layer). Wait for the elastic material and conductive elastic material to penetrate into the conductive fabric and completely cure.

[0046] Step 3: Use a laser to cut the solidified elastic material on the conductive fabric (top conductive layer) at a fixed depth to obtain a supporting micropillar array. Then, use a laser to cut the solidified conductive elastic material on the conductive fabric (bottom conductive layer) at a fixed depth to obtain a transition micropillar array. Then, cut the top of the transition micropillar array at a fixed depth to obtain a controllable micropillar array. The gradient range of the controllable micropillar array can be controlled by adjusting the laser cutting power.

[0047] Step 4: Immerse the support micropillar array halfway into the adhesive, ensuring that the lower half of each support micropillar is fully coated with adhesive.

[0048] Step 5: Align the adhesive-coated support micropillar array with the gaps in the control micropillar array, and press them firmly downwards. Then, place the entire device in an oven to dry and heat until the adhesive is completely cured and bonded, resulting in a grouped micropillar structure fabric-based flexible strain sensor.

[0049] Example:

[0050] In one specific embodiment, reference is made to Figure 1 As shown, the grouped micropillar structure fabric-based flexible strain sensor consists of two structural modules: a top conductive layer 1 and a supporting micropillar array 2, and a bottom conductive layer 5 and a control micropillar array 3. Both the top conductive layer 1 and the bottom conductive layer 5 are conductive fabrics. First, a liquid metal mixture of sodium and gallium (mass ratio 3:1) is dispersed in ethanol to obtain a dispersion. Then, a knitted cotton fabric is completely immersed in the dispersion and left for 30 minutes to allow the dispersion to fully penetrate the fabric. Afterward, the soaked knitted cotton fabric is placed in an oven and heated at 80 degrees Celsius for 2 hours to cure, resulting in the conductive fabric.

[0051] Reference Figure 2 As shown, the fabrication process of the grouped micropillar structure cloth-based flexible strain sensor mainly consists of the following four steps:

[0052] First, liquid PDMS is coated onto the conductive fabric (top conductive layer) 1 to a thickness of approximately 5-8 mm. It is then placed in an oven at 60 degrees Celsius for 5 hours to allow the PDMS to fully cure. During this process, the liquid PDMS penetrates into the conductive fabric (top conductive layer) 1, improving the overall structural strength. Simultaneously, conductive ink with a silver powder solid content of 65% is doped into the liquid PDMS and stirred for 30 minutes to ensure complete integration, resulting in liquid conductive PDMS. This conductive PDMS is then coated onto the surface of the conductive fabric (bottom conductive layer) 5 to a thickness of approximately 5-8 mm and placed in an oven at 60 degrees Celsius for 5 hours to allow the conductive PDMS to fully cure. Again, during this process, the liquid conductive PDMS penetrates into the conductive fabric (bottom conductive layer) 5, improving the overall structural strength.

[0053] The second step involves first using a laser to cut the PDMS cured on the conductive fabric (top conductive layer) 1 at a fixed depth, obtaining the supporting micropillar array 2. The cutting depth is approximately 4–7 mm. The supporting micropillars have a diameter of approximately 1 mm, and the array spacing is approximately 1–2 mm. Then, using a laser to cut the conductive PDMS cured on the conductive fabric (bottom conductive layer) 5 at a fixed depth, the cutting depth is approximately 4–7 mm, obtaining the transition micropillar array. The micropillars have a diameter of approximately 2–3 mm, and the array spacing is 2–3 mm. Finally, using a laser to cut the top of the transition micropillar array at a fixed depth, obtaining the controllable micropillar array 3. The maximum height of the controllable micropillar array 3 is less than 8 mm, and the gradient range is approximately 1–2 mm.

[0054] The third step involves holding the conductive fabric (bottom conductive layer) 5 and partially immersing the support micropillar array 2 in the adhesive 4, ensuring that the adhesive 4 completely covers the lower half of each support micropillar and that the top of each support micropillar is adequately covered by the adhesive 4.

[0055] The fourth step involves observing the conductive fabric (top conductive layer) 1 under a stereomicroscope. The conductive fabric is clamped and fixed onto a micro-motion platform that allows for movement, tilting, and rotation along the XYZ axes. The supporting micropillar array 2, wrapped with adhesive 4, is aligned with the gaps in the regulating micropillar array 3 and then pressed firmly downwards. The entire device is then placed in an oven and heated at 60 degrees Celsius for 1 hour until the adhesive 4 is fully cured and bonded, resulting in a grouped micropillar structure fabric-based flexible strain sensor.

[0056] Reference Figure 3 The diagram illustrates the working mechanism of a grouped micropillar structure fabric-based flexible strain sensor. Figure (a) shows a schematic diagram of the grouped micropillar structure fabric-based flexible strain sensor in the strain-free state, where the top of the micropillar array does not contact the conductive fabric (top conductive layer) 1, and there is no conductive path between the conductive fabric (top conductive layer) 1 and the conductive fabric (bottom conductive layer) 5, resulting in infinite resistance. Figure (b) shows a schematic diagram of the grouped micropillar structure fabric-based flexible strain sensor in the small strain state, where only the left-hand micropillar contacts the conductive fabric (top conductive layer) 1, forming a conductive path between the conductive fabric (top conductive layer) 1 and the conductive fabric (bottom conductive layer) 5, generating a relatively large resistance. As the strain increases, more and more micropillars contact the conductive fabric (top conductive layer) 1, the conductive path area increases gradually, and the equivalent resistance between the conductive fabric (top conductive layer) 1 and the conductive fabric (bottom conductive layer) 5 decreases gradually, achieving a negative resistance effect flexible strain sensor where resistance decreases with increasing stress.

[0057] In another specific embodiment, the gradient of the micropillar array is optimized, such as... Figure 4As shown. To improve the sensitivity of the grouped micropillar structure fabric-based flexible strain sensor for strain detection, the diameter, position distribution, and gradient distribution of the micropillar array 3 can be redesigned and adjusted when laser-cutting the conductive PDMS already cured on the conductive fabric (bottom conductive layer) 5. With a consistent overall height range, the smaller the gradient interval range, the greater the number of gradient intervals, and the greater the number of adjustable micropillars, the greater the sensitivity for strain detection. The minute strain applied to the grouped micropillar structure fabric-based flexible strain sensor will also generate a resistance change between the conductive fabric (top conductive layer) 1 and the conductive fabric (bottom conductive layer) 5.

[0058] In another specific embodiment, the distribution of the supporting micropillar array is optimized, such as... Figure 5 As shown. To improve the strain detection limit and overall structural strength of the grouped micropillar structure fabric-based flexible strain sensor, the distribution of the supporting micropillar array 2 can be redesigned and its density increased during laser-cutting of the PDMS already cured on the conductive fabric (fixed-part conductive layer) 1. This allows the supporting micropillars to surround and control the micropillar arrangement. The more numerous and denser the supporting micropillars, the higher the strain detection limit and the greater the overall structural strength of the grouped micropillar structure fabric-based flexible strain sensor.

Claims

1. A grouped micropillar structure cloth-based flexible strain sensor, characterized in that, It includes a top conductive layer, a supporting micropillar array, a regulating micropillar array, and a bottom conductive layer; Both the top conductive layer and the bottom conductive layer are conductive fabrics; The conductive fabric is made by combining cloth with a metal polymer conductor or metal particles; The supporting micropillar array uses an elastic material as a substrate and includes a supporting micropillar base and multiple supporting micropillars; The supporting micropillar base is attached to the top conductive layer; The supporting micro-column is columnar, with one end integrated with the supporting micro-column base; The controllable micropillar array uses a conductive elastic material as a substrate, including a controllable micropillar base and multiple controllable micropillars; the controllable micropillar base is attached to the bottom conductive layer; The control micro-column is columnar, with one end integrated with the control micro-column base and the other end suspended in the air; The multiple control micropillars are of different heights and arranged in a stepped manner; The other end of the supporting micropillar contacts the control micropillar base and is bonded together with an adhesive.

2. The grouped micropillar structure cloth-based flexible strain sensor according to claim 1, characterized in that, The conductive fabric is made by combining ordinary fabric with metal polymer conductors or metal particles through electrolytic plating, metal coating, or metal cladding.

3. The grouped micropillar structure cloth-based flexible strain sensor according to claim 1, characterized in that, The elastic material is polydimethylsiloxane (PDMS), polyurethane (TPU), polyvinylidene fluoride (PVDF), or polynaphthalene ester (PEN).

4. The grouped micropillar structure cloth-based flexible strain sensor according to claim 1, characterized in that, The conductive elastic material is polydimethylsiloxane (PDMS), polyurethane (TPU), polyvinylidene fluoride (PVDF), or polynatyl ester (PEN) elastic material, and its conductivity is achieved by doping with carbon nanotubes, carbon black, liquid metal, or conductive polymers.

5. The grouped micropillar structure cloth-based flexible strain sensor according to claim 1, characterized in that, The supporting micropillars are cylindrical, with a height of 4-7 mm and a diameter of 1 mm, and are spaced 1-2 mm apart.

6. The grouped micropillar structure cloth-based flexible strain sensor according to claim 1, characterized in that, The control micropillars are cylindrical with a diameter of 2-3 mm, the spacing between the control micropillars is 2-3 mm, and the height difference between the control micropillars is 1-2 mm.

7. A method for fabricating a grouped micropillar structure cloth-based flexible strain sensor as described in claim 1, comprising the following specific steps: Step 1: Immerse the knitted cotton fabric in a dispersion of liquid metal and ethanol, wait for the dispersion to completely saturate the knitted cotton fabric, and then place it in an oven to heat and solidify, thus obtaining a conductive fabric; Step 2: Take two pieces of conductive fabric as the top conductive layer and the bottom conductive layer respectively; apply liquid elastic material to the surface of the top conductive layer and apply liquid conductive elastic material to the surface of the bottom conductive layer, so that the elastic material and conductive elastic material penetrate into the conductive fabric and are completely cured; Step 3: Use laser to cut the elastic material solidified on the top conductive layer to obtain a support micropillar array; use laser to cut the conductive elastic material solidified on the bottom conductive layer to obtain a transition micropillar array of equal height; then cut the top of the transition micropillar array to obtain a control micropillar array with height stepped arrangement (3). Step 4: Immerse the support micropillar array halfway into the adhesive, ensuring that the lower half of each support micropillar is wrapped in the adhesive; Step 5: Align the support micropillar array, which is wrapped with adhesive, with the gap of the control micropillar array, so that the support micropillar array contacts the control micropillar base and is then pressed downwards. Then, the whole assembly is placed in an oven to dry and heat until the adhesive is completely cured and bonded, resulting in a grouped micropillar structure cloth-based flexible strain sensor.

8. The processing method according to claim 7, characterized in that, The conductive fabric is obtained by dispersing liquid metals of sodium and gallium in a mass ratio of 3:1 in ethanol to obtain a dispersion, then completely immersing knitted cotton fabric in the dispersion, waiting for 30 minutes to allow the dispersion to fully penetrate the knitted cotton fabric, and then placing it in an oven to be heated and dried at 80 degrees Celsius for 2 hours.

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