Omnidirectional flexible stretchable sensor based on bionic structure and preparation method thereof

Abstract

The invention discloses an omnidirectional flexible stretchable sensor based on a bionic structure and a preparation method thereof. The sensor comprises a net-shaped sensing layer array composed of long-strip-shaped sensing units with bionic crack structures, a snake-shaped insulation connecting layer used for independently connecting the near ends of the sensing units, metal wires electrically connected with the far ends of the sensing units and a packaging layer wrapping the whole. The preparation method comprises the following steps: dispersing the multi-walled carbon nanotubes and the MXene nanosheets, and mixing the dispersed multi-walled carbon nanotubes and MXene nanosheets with PDMS to prepare conductive slurry; a bionic crack sensing unit array is formed through blade coating of a 3D printing mold; pDMS is filled in a snake-shaped mold to form an insulating connection layer; and packaging and stripping are completed by adopting a polyacrylic acid sacrificial layer process after the lead is connected. Through the coupling design of the bionic crack and the snake-shaped structure, high-sensitivity and high-distinction-degree sensing of multi-direction strain is achieved, excellent stretchability and signal stability are achieved at the same time, and the device is particularly suitable for precise rehabilitation monitoring of multi-degree-of-freedom joint movement of knee joints and the like.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of flexible electronics, and in particular to an omnidirectional flexible stretchable sensor based on a bionic structure and a preparation method thereof. BACKGROUND

[0002] The rehabilitation treatment of diseases such as knee joint injury highly depends on the accurate monitoring of joint range of motion to evaluate the rehabilitation effect, identify abnormal compensatory movements and guide the training program. As a complex weight-bearing joint, the knee joint movement covers flexion, internal rotation, external rotation and other degrees of freedom, accompanied by the coordination and compensation of multiple muscle groups. For example, the "knee joint internal buckling" commonly seen in gait is a typical compensatory movement, which is easy to lead to joint deformity and muscle imbalance if not discovered and corrected in time, seriously affecting the rehabilitation process.

[0003] However, the traditional knee joint range of motion monitoring technology has significant limitations, which is difficult to meet the needs of modern precision rehabilitation, mainly in the following three aspects: (1) Single sensing dimension: The most commonly used mechanical protractor in clinical practice can only measure the flexion angle of a single dimension, and cannot capture the internal / external rotation and muscle force direction information. This leads to the fact that the rehabilitation therapist cannot fully understand the real movement state of the joint, and the program development lacks data support. Although the optical motion capture system can realize multi-dimensional monitoring, it is expensive, requires a fixed laboratory environment, and is easily blocked, which cannot be applied to daily rehabilitation training scenes.

[0004] (2) Poor fit and comfort: Traditional rigid sensors or early flat flexible sensors are difficult to be closely attached to irregular curved surfaces such as human knee joints for a long time. When attached, the edges are prone to lifting, resulting in signal distortion or falling off, and long-term wear is uncomfortable, affecting the continuity and accuracy of monitoring.

[0005] (3) Insufficient dynamic adaptability: During the gait cycle of the knee joint, the skin on the lateral side will undergo complex and large dynamic deformation. Early flexible sensors are mostly based on polydimethylsiloxane PDMS (polydimethylsiloxane PDMS) and carbon nanotube composites, which have limited stretchability and are prone to conductive network fracture under repeated large deformation, resulting in signal failure. More importantly, these sensors are designed for "one-way sensing", i.e., they can only respond to pressure perpendicular to their surface or stretching in a single direction. When the knee joint performs a compound movement (such as flexion accompanied by internal rotation), the sensor cannot distinguish the mechanical signals in different directions and can only output a coupled overall signal, which makes the rehabilitation system unable to identify compensatory movements and may even make incorrect judgments.

[0006] In view of the above problems, researchers at home and abroad have attempted to develop omnidirectional flexible sensors. For example: Chinese patent application CN118960544A discloses an omnidirectional flexible strain sensor and a preparation method. The patent application uses Ecoflex solution to drop coat and package the sensor as a whole. However, the overall packaging will severely limit the free deformation of the internal microstructure of the sensor, weaken the high stretchability that the snake-shaped design should bring, and significantly reduce the strain sensitivity, making it difficult to accurately capture the small strain signal in the knee joint movement.

[0007] Chinese patent application CN111649665A discloses a spiderweb-like flexible strain sensor that can identify strain direction. The patent application uses a customized spiderweb structure. However, it has two obvious defects: first, the units of the spiderweb structure are made of the same conductive material and are connected to each other, resulting in serious crosstalk between the sensing units, which cannot achieve true independent measurement; second, the structure lacks bionic crack design and snake-shaped interconnection design, resulting in limited sensor sensitivity and stretchability.

[0008] In summary, the flexible sensors in the prior art have deficiencies in structural design and packaging strategy, and cannot meet the requirements of multi-directional perception, high adhesion, high stretchability, and high sensitivity. Therefore, there is an urgent need in the art for a new omnidirectional flexible stretchable sensor that can break through technical bottlenecks in terms of material system and structural design to achieve accurate, dynamic, and long-term monitoring of multi-degree-of-freedom motion of the knee joint and the like. SUMMARY

[0009] To solve the technical problems in the background art, the present application proposes an omnidirectional flexible stretchable sensor based on bionic structure and a preparation method thereof.

[0010] The omnidirectional flexible stretchable sensor based on bionic structure proposed by the present application comprises: a network of sensor layer arrays composed of at least three radially extending long strip-shaped sensing units with bionic crack structure on the surface; a snake-shaped insulating connection layer that independently connects the proximal ends of each long strip-shaped sensing unit to a central region; a plurality of metal wires electrically connected to the distal ends of each long strip-shaped sensing unit through conductive silver glue; a packaging layer covering the upper and lower surfaces and the side surfaces of the network of sensor layer arrays and the snake-shaped insulating connection layer.

[0011] Preferably, the long strip-shaped sensing units are uniformly distributed radially with the central region as the center.

[0012] Preferably, the number of the elongated sensing units is six, and the distribution angles of the six elongated sensing units are 0 degrees, 60 degrees, 120 degrees, 180 degrees, 240 degrees and 300 degrees, respectively.

[0013] Preferably, the serpentine insulating connection layer is made of polydimethylsiloxane (PDMS) material; the encapsulation layer is made of polydimethylsiloxane (PDMS) material; and the elongated sensing unit is made of a polydimethylsiloxane (PDMS) composite conductive material comprising multi-walled carbon nanotubes and MXene nanosheets.

[0014] Preferably, the mass ratio of the multi-walled carbon nanotubes to MXene nanosheets is 1:1.

[0015] Preferably, the elongated sensing unit is capable of generating differentiated resistance change signals under strain in multiple directions.

[0016] This invention proposes a method for fabricating an omnidirectional flexible stretchable sensor based on a biomimetic structure, applicable to the omnidirectional flexible stretchable sensor described in any of the above claims. The method includes the following steps: Multi-walled carbon nanotubes and MXene nanosheets, two conductive fillers, were mixed with an organic solvent and then ultrasonically dispersed until the fillers were uniformly dispersed to obtain a conductive filler dispersion. Polydimethylsiloxane (PDMS) prepolymer was added to the conductive filler dispersion, and the solvent was evaporated and the mixture was homogeneous by heating and stirring to obtain a conductive nanocomposite slurry. The conductive nanocomposite material slurry is coated onto a mold with a biomimetic crack microstructure on its surface and then cured to form a long strip-shaped sensing unit array with a biomimetic crack structure. The long strip-shaped sensing unit array is arranged in a serpentine groove mold with insulating material, so that each long strip-shaped sensing unit is isolated from each other. After curing, a mesh sensing layer array is formed by the serpentine insulating connecting layer that is independently connected to each other. A conductive adhesive is used to electrically connect the metal wires to the ends of each strip-shaped sensing unit in the mesh sensing layer array. A water-soluble polymer solution is coated onto a substrate and cured to form a sacrificial layer; The mesh sensing layer array connected with metal wires is encapsulated, and the encapsulated sensor is separated from the substrate by dissolving the sacrificial layer in deionized water, ultimately obtaining the independent omnidirectional flexible stretchable sensor.

[0017] Preferably, the mass ratio of the multi-walled carbon nanotubes to MXene nanosheets is 1:1; the ultrasonic dispersion treatment has a power of 80-120W, a frequency of 3kHz-5kHz, and a time of 1-3 hours; the heating and stirring treatment has a temperature of 30-40℃, a stirring speed of 600-900rpm, and a treatment time of 2-4 hours; the polydimethylsiloxane PDMS prepolymer comprises a matrix and a curing agent, with a mass ratio of matrix to curing agent of 6:1 to 14:1; the curing treatment is performed at room temperature for 20-30 hours; the water-soluble polymer is polyacrylic acid, and the polymer solution is prepared by mixing deionized water and polyacrylic acid in a mass ratio of 4:1 to 10:1.

[0018] Preferably, the number of the serpentine grooves increases in a gradient from the center of the array to the edge.

[0019] Preferably, the coating is spin coating, and the spin coating parameters are: first spin coating at a speed of 400-800 rpm for 5-7 seconds, and then spin coating at a speed of 1500-2000 rpm for 25-35 seconds; the curing heating conditions are 75-85℃ for 15-25 minutes; the sacrificial layer is dissolved after being immersed in deionized water for 2-7 minutes.

[0020] This invention presents an omnidirectional flexible stretchable sensor based on a biomimetic structure and its fabrication method. Through the synergistic design of a biomimetic crack structure and a radial sensing array, it achieves high sensitivity and high discrimination in sensing multi-directional strain, enabling precise decoupling of complex multi-degree-of-freedom composite movements of joints such as the knee. A composite system combining high conductivity, high tensile strength, and good biocompatibility is constructed using a two-phase conductive filler composed of MXene and multi-walled carbon nanotubes and a PDMS elastic matrix, ensuring signal stability and wearing comfort under repeated large deformations. A unique serpentine insulating connection layer design effectively releases stress, avoids mechanical crosstalk between sensing units, and endows the sensor with extremely high overall tensile performance. The sacrificial layer-based encapsulation and peeling process simplifies the fabrication process and ensures the integrity of the complex three-dimensional structure. This sensor provides an advanced monitoring solution for the field of sports rehabilitation, integrating "multi-directional sensing, comfortable fit, and dynamic stability." Attached Figure Description

[0021] Figure 1 This is a schematic diagram of ultrasonic dispersion of two-phase conductive fillers in a beaker, representing a method for fabricating an omnidirectional flexible stretchable sensor based on a biomimetic structure proposed in this invention. Figure 2 This is a schematic diagram of the process of dispersing two-phase conductive filler and PDMS in a beaker and heating and magnetic stirring in a method for fabricating an omnidirectional flexible stretchable sensor based on a biomimetic structure proposed in this invention. Figure 3This is a schematic diagram of the process of spin-coating conductive nanocomposite material onto the surface of a biomimetic resin mold in a method for fabricating an omnidirectional flexible stretchable sensor based on a biomimetic structure, as proposed in this invention. Figure 4 This is a schematic diagram of the demolding process of an omnidirectional flexible stretchable sensor based on a biomimetic structure, as proposed in this invention.

[0022] Figure 5 This invention provides a schematic diagram of the fabrication process for an omnidirectional flexible stretchable sensor based on a biomimetic structure. Figure 1 ; Figure 6 This invention provides a schematic diagram of the fabrication process for an omnidirectional flexible stretchable sensor based on a biomimetic structure. Figure 2 ; Figure 7 This is a schematic diagram of the composition structure of an omnidirectional flexible stretchable sensor based on a biomimetic structure proposed in this invention. Figure 8 This is a top view of an omnidirectional flexible stretchable sensor based on a biomimetic structure proposed in this invention.

[0023] Figure 9 This is a three-dimensional structural diagram of an omnidirectional flexible stretchable sensor based on a biomimetic structure proposed in this invention. Figure 10 This is a schematic diagram illustrating the design principle of an omnidirectional flexible stretchable sensor based on a biomimetic structure proposed in this invention. Figure 11 This is a schematic diagram illustrating the omnidirectional sensing principle of an omnidirectional flexible stretchable sensor based on a biomimetic structure proposed in this invention. Figure 12 This is a comparison of the stretching rates of a biomimetic omnidirectional flexible stretchable sensor proposed in this invention, specifically a stretchable sensor without a biomimetic crack structure and a stretchable sensor with biomimetic crack structures of different spacings. Figure 13 This is a comparison chart of the stretchability of a stretchable sensor with a long strip insulating connecting layer and a stretchable sensor with a serpentine insulating connecting layer, based on a biomimetic omnidirectional flexible stretchable sensor proposed in this invention.

[0024] Legend: 1. Multi-walled carbon nanotubes; 2. MXene nanosheets; 3. Beaker; 4. Polydimethylsiloxane (PDMS); 5. Conductive nanocomposite slurry; 6. Magnetic stirrer; 7. Bionic resin mold; 7-1. Bionic crack structure; 8. Filled serpentine mold; 9. Serpentine insulating connection layer; 10. Mesh sensing layer array; 11. Conductive silver paste; 12. Metal wire; 13. Glass slide; 13-1. Deionized water; 13-2. Polyacrylic acid reagent; 13-3. Polyacrylic acid solution. Detailed Implementation

[0025] Reference Figures 1-13 The present invention proposes an omnidirectional flexible stretchable sensor based on a biomimetic structure, comprising: A mesh sensing layer array 10 consists of at least three radially extending strip-shaped sensing units with biomimetic crack structures on their surfaces.

[0026] In this embodiment, the elongated sensing units are evenly distributed radially with the central region as the center.

[0027] In this embodiment, there are six elongated sensing units, and the distribution angles of the six elongated sensing units are 0 degrees, 60 degrees, 120 degrees, 180 degrees, 240 degrees and 300 degrees, respectively.

[0028] Specifically, the elongated sensing unit can generate differentiated resistance change signals under strain in multiple directions.

[0029] A serpentine insulating connection layer 9 connects the proximal ends of each elongated sensing unit independently to a central region.

[0030] In this embodiment, the serpentine insulating connection layer 9 is made of polydimethylsiloxane PDMS material; the encapsulation layer is made of polydimethylsiloxane PDMS material; and the elongated sensing unit is made of polydimethylsiloxane PDMS composite conductive material containing multi-walled carbon nanotubes and MXene nanosheets.

[0031] Specifically, the mass ratio of multi-walled carbon nanotubes to MXene nanosheets is 1:1.

[0032] Multiple metal wires 12 are electrically connected to the far end of each strip-shaped sensing unit via conductive silver paste 11.

[0033] An encapsulation layer covers the upper and lower surfaces and sides of the mesh sensing layer array 10 and the serpentine insulating connection layer 9.

[0034] Reference Figures 1-13This invention proposes a method for fabricating an omnidirectional flexible stretchable sensor based on a biomimetic structure, applicable to any of the omnidirectional flexible stretchable sensors described above. The method includes the following steps: Multi-walled carbon nanotubes and MXene nanosheets, two conductive fillers, were mixed with an organic solvent and then ultrasonically dispersed until the fillers were uniformly dispersed to obtain a conductive filler dispersion. Polydimethylsiloxane (PDMS) prepolymer was added to a conductive filler dispersion, and the solvent was evaporated and the mixture was homogeneous by heating and stirring to obtain a conductive nanocomposite slurry. The conductive nanocomposite material slurry is scraped onto a mold with a biomimetic crack microstructure on the surface, and then cured to form a strip-shaped sensing unit array with a biomimetic crack structure. The long strip-shaped sensing unit array is arranged in a serpentine groove mold with insulating material, so that each long strip-shaped sensing unit is isolated from each other. After curing, a mesh sensing layer array 10 is formed by the serpentine insulating connection layer 9 being independently connected to each other. The metal wires 12 are electrically connected to the ends of each strip-shaped sensing unit in the mesh sensing layer array 10 using a conductive adhesive. A water-soluble polymer solution is coated onto a substrate and cured to form a sacrificial layer; The mesh sensing layer array 10 connected with metal wires 12 is encapsulated, and the encapsulated sensor is separated from the substrate by dissolving the sacrificial layer in deionized water, thus obtaining an independent omnidirectional flexible stretchable sensor.

[0035] Specifically, the mass ratio of multi-walled carbon nanotubes to MXene nanosheets is 1:1; the ultrasonic dispersion treatment has a power of 80-120W, a frequency of 3kHz-5kHz, and a time of 1-3 hours; the heating and stirring treatment has a temperature of 30-40℃, a stirring speed of 600-900rpm, and a treatment time of 2-4 hours; the polydimethylsiloxane PDMS prepolymer includes a matrix and a curing agent, with a mass ratio of matrix to curing agent of 6:1 to 14:1; the curing treatment is performed at room temperature for 20-30 hours; the water-soluble polymer is polyacrylic acid, and the polymer solution is prepared by mixing deionized water and polyacrylic acid in a mass ratio of 4:1 to 10:1.

[0036] It should be noted that the number of serpentine grooves increases in a gradient from the center of the array to the edge.

[0037] In this embodiment, the spin coating parameters are as follows: first spin coating at a speed of 500-700 rpm for 5-7 seconds, then spin coating at a speed of 1300-1700 rpm for 25-35 seconds; the curing temperature is 75-85℃ for 15-25 minutes; the sacrificial layer is dissolved after being immersed in deionized water for 3-7 minutes.

[0038] Example 1: like Figure 1 As shown, 0.1 g of multi-walled carbon nanotubes 1 and 0.1 g of MXene nanosheets 2 (mass ratio 1:1) were added to 15 mL of naphtha solvent and placed in beaker 3. Beaker 3 was placed in an ultrasonic instrument and ultrasonically dispersed at a power of 100 W and a frequency of 4 kHz for 2 hours to form a uniform conductive filler dispersion.

[0039] like Figure 2 As shown, 5g of polydimethylsiloxane PDMS4 (matrix: curing agent = 10:1) was added to the above conductive filler dispersion. The beaker 3 was placed on the magnetic stirrer 6 and stirred at 35°C and 800rpm for 3 hours to allow the solvent to fully evaporate, resulting in a uniform and viscous conductive nanocomposite slurry 5.

[0040] like Figure 3 As shown, a biomimetic resin mold 7 with a biomimetic crack microstructure 7-1 on its surface was prepared using 3D printing technology. A conductive nanocomposite slurry 5 was coated onto the surface of the biomimetic resin mold 7, and the coating process was repeated 10 times to ensure that the conductive nanocomposite slurry 5 uniformly filled the cracks. After curing at room temperature for 24 hours, a strip-shaped sensing unit array with the biomimetic crack structure 7-1 was obtained upon demolding.

[0041] like Figure 4 As shown, a serpentine mold 8 is prepared using 3D printing. The aforementioned sensor unit array is precisely placed in the corresponding positions of the serpentine mold 8, isolating each sensor unit from the others. Polydimethylsiloxane (PDMS4) is coated into the serpentine grooves and cured at room temperature for 24 hours to form a serpentine insulating connection layer 9, thereby constituting a complete mesh sensor layer array 10.

[0042] like Figure 5 As shown, a deionized water and polyacrylic acid solution 13-3 with a mass ratio of 5:1 was prepared. This solution was spin-coated onto a clean glass slide 13 using the following parameters: low speed 600 rpm / 6 s, high speed 1500 rpm / 30 s. Subsequently, it was heated on an 80°C hot plate for 20 minutes to cure and form a polyacrylic acid sacrificial layer. The mesh sensing layer array 10, connected with metal wires 12, was immersed in a polydimethylsiloxane (PDMS4) solution. After encapsulation, it was placed on the glass slide 13 with the sacrificial layer and cured at room temperature.

[0043] like Figure 6 As shown, the entire structure described above is immersed in a petri dish containing deionized water 13-1. After about 5 minutes, the polyacrylic acid sacrificial layer completely dissolves, and the encapsulated sensor detaches from the glass slide 13. It is then removed with tweezers, rinsed lightly with deionized water, and air-dried to obtain the final omnidirectional flexible stretchable sensor.

[0044] likeFigure 7 As shown, fine metal wires 12 are bonded to the ends of each sensing unit in the mesh sensing layer array 10 using conductive silver paste 11. The bonding is then allowed to cure at room temperature for 24 hours to ensure reliable electrical connections.

[0045] like Figure 9 As shown, the sensor is composed of an upper polydimethylsiloxane (PDMS) encapsulation layer, a metal wire 12 and conductive silver paste 11, a serpentine insulating connection layer 9, a mesh sensing layer array 10 and a lower polydimethylsiloxane (PDMS) encapsulation layer.

[0046] like Figure 10 As shown, the design of the sensor in this invention is inspired by the biological structure of a lobster's tail. Its biomimetic crack structure 7-1 is inspired by the microscopic cracks in the cuticle layer of a lobster's tail, a structure that is extremely sensitive to external strain. The design of the serpentine insulating connection layer 9 ensures the mechanical independence of each sensing unit and the high tensile strength of the overall structure.

[0047] like Figure 11 As shown, the sensor's sensing principle lies in the fact that six radially distributed sensing units (with orientation angles of 0°, 60°, 120°, 180°, 240°, and 300°) form an omnidirectional sensing array. When the sensor is subjected to strain in different directions, each unit produces a differentiated resistance change (ΔR / R0) due to its different orientation. By analyzing the combination of these signals (such as amplitude, ratio, or phase difference), the precise direction and magnitude of the applied strain can be calculated.

[0048] like Figure 12 As shown, the comparison of the stretchability of the stretchable sensor without the biomimetic crack structure and the stretchable sensor with different spacing of the biomimetic crack structure is presented. The results show that the sensor with a spacing of 1 mm using the biomimetic crack structure has a greater resistance change under the same strain, which confirms that the use of the biomimetic crack structure can improve the sensitivity of the sensor and optimize its spacing.

[0049] like Figure 13 As shown, the stretchability of a stretchable sensor with a long strip insulating connection layer and a stretchable sensor with a serpentine insulating connection layer are illustrated. The results show that the sensor with the serpentine insulating connection layer has a greater stretchability, which can meet the application requirements in large strain scenarios.

[0050] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. An omnidirectional flexible stretchable sensor based on a biomimetic structure, characterized in that, include: A mesh sensing layer array (10) consists of at least three radially extending strip-shaped sensing units with biomimetic crack structures on their surfaces; A serpentine insulating connection layer (9) connects the proximal ends of each of the elongated sensing units independently to a central region. Multiple metal wires (12) are electrically connected to the far end of each of the elongated sensing units via conductive silver paste (11); An encapsulation layer covers the upper and lower surfaces and sides of the mesh sensing layer array (10) and the serpentine insulating connection layer (9).

2. The omnidirectional flexible stretchable sensor based on a biomimetic structure according to claim 1, characterized in that, The elongated sensing units are evenly distributed radially around the central region.

3. The omnidirectional flexible stretchable sensor based on a biomimetic structure according to claim 2, characterized in that, The number of the elongated sensing units is six, and the distribution angles of the six elongated sensing units are 0 degrees, 60 degrees, 120 degrees, 180 degrees, 240 degrees and 300 degrees respectively.

4. The omnidirectional flexible stretchable sensor based on a biomimetic structure according to claim 1, characterized in that, The serpentine insulating connection layer (9) is made of polydimethylsiloxane PDMS material; the encapsulation layer is made of polydimethylsiloxane PDMS material; and the elongated sensing unit is made of polydimethylsiloxane PDMS composite conductive material containing multi-walled carbon nanotubes and MXene nanosheets.

5. The omnidirectional flexible stretchable sensor based on a biomimetic structure according to claim 4, characterized in that, The mass ratio of the multi-walled carbon nanotubes to MXene nanosheets is 1:

1.

6. The omnidirectional flexible stretchable sensor based on a biomimetic structure according to claim 1, characterized in that, The elongated sensing unit can generate differentiated resistance change signals under strain in multiple directions.

7. A method for fabricating an omnidirectional flexible stretchable sensor based on a biomimetic structure, characterized in that, Applied to the omnidirectional flexible stretchable sensor as described in any one of claims 1-6, the method includes the following steps: Multi-walled carbon nanotubes and MXene nanosheets, two conductive fillers, were mixed with an organic solvent and then ultrasonically dispersed until the fillers were uniformly dispersed to obtain a conductive filler dispersion. Polydimethylsiloxane (PDMS) prepolymer was added to the conductive filler dispersion, and the solvent was evaporated and the mixture was homogeneous by heating and stirring to obtain a conductive nanocomposite slurry. The conductive nanocomposite material slurry is coated onto a mold with a biomimetic crack microstructure on its surface and then cured to form a long strip-shaped sensing unit array with a biomimetic crack structure. The long strip-shaped sensing unit array is arranged in a serpentine groove mold with insulating material, so that each long strip-shaped sensing unit is isolated from each other. After curing, a mesh sensing layer array (10) is formed by the serpentine insulating connecting layer (9) being independently connected to each other. Using a conductive adhesive, the metal wires (12) are electrically connected to the ends of each strip-shaped sensing unit in the mesh sensing layer array (10); A water-soluble polymer solution is coated onto a substrate and cured to form a sacrificial layer; The mesh sensing layer array (10) connected with metal wires (12) is encapsulated, and the encapsulated sensor is separated from the substrate by dissolving the sacrificial layer in deionized water, thus obtaining the independent omnidirectional flexible stretchable sensor.

8. The method for fabricating an omnidirectional flexible stretchable sensor based on a biomimetic structure according to claim 7, characterized in that, The mass ratio of the multi-walled carbon nanotubes to MXene nanosheets is 1:1; the ultrasonic dispersion treatment has a power of 80-120W, a frequency of 3kHz-5kHz, and a time of 1-3 hours; the heating and stirring treatment has a temperature of 30-40℃, a stirring speed of 600-900rpm, and a treatment time of 2-4 hours; the polydimethylsiloxane PDMS prepolymer includes a matrix and a curing agent, with a mass ratio of matrix to curing agent of 6:1 to 14:1; the curing treatment is performed at room temperature for 20-30 hours; the water-soluble polymer is polyacrylic acid, and the polymer solution is prepared by mixing deionized water and polyacrylic acid in a mass ratio of 4:1 to 10:

1.

9. The method for fabricating an omnidirectional flexible stretchable sensor based on a biomimetic structure according to claim 7, characterized in that, The number of the serpentine grooves increases in a gradient from the center of the array to the edge.

10. The method for fabricating an omnidirectional flexible stretchable sensor based on a biomimetic structure according to claim 7, characterized in that, The coating is spin-coated, and the spin-coating parameters are as follows: first spin-coat at a speed of 400-800 rpm for 5-7 seconds, then spin-coat at a speed of 1500-2000 rpm for 25-35 seconds; the curing temperature is 75-85℃ for 15-25 minutes; the sacrificial layer is dissolved after being immersed in deionized water for 2-7 minutes.

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