Ultrathin breathable soft strain sensor and preparation method thereof

Abstract

The invention discloses an ultrathin breathable soft strain sensor and a preparation method thereof. The preparation method comprises the following steps: S1, preparing a soft substance substrate with micron-sized thickness and similar soft tissue Young modulus; and S2, based on a particle phagocytosis effect, controllably embedding conductive micro-nano particles on the substrate to form a conductive seepage network, and packaging to obtain the soft strain sensor, and S3, constructing a ventilation channel on the sensor by using a laser etching technology. The method is characterized in that the limitation of chemical non-orthogonality and complex fluid dynamics in a traditional method is effectively avoided by utilizing the particle phagocytic effect, and the strain response controllable conductive network construction is successfully realized on the ultrathin low-modulus soft substrate; according to the method, core performance parameters such as sensitivity, strain limit and hysteresis of the sensor can be accurately regulated and controlled, and the differentiated detection requirements of different parts of a human body on the sensitivity and the strain range are met; meanwhile, the air permeability of the device is remarkably improved through the air-permeable through holes constructed through laser etching, and the overall sensing performance of the device is further optimized.

Description

Technical Field

[0001] This invention relates to the field of soft strain sensor technology, specifically to an ultrathin, breathable soft strain sensor and its fabrication method. Background Technology

[0002] Strain sensors can be used to monitor important physiological signals such as heart rate, respiration, and gait. Their mechanical properties and breathability have a significant impact on long-term continuous monitoring performance. Strain sensors that combine tissue-like Young's modulus and micron-level thickness can fit closely to complex surfaces such as skin and joints like an "electronic tattoo," achieving a super-fit design that reduces or even eliminates motion artifacts and improves monitoring accuracy. Good breathability ensures that sweat secreted by the skin can evaporate promptly, preventing sweat buildup that can cause discomfort and device detachment, thus improving the user experience while maintaining sensing accuracy.

[0003] Fabricating soft strain sensors with soft tissue modulus typically relies on solution methods, requiring the dispersion of micro / nanomaterials into a soft matter precursor to form an ink, followed by patterning. When used in soft strain sensor fabrication, the ink must simultaneously satisfy hydrodynamic properties (such as adhesion and surface tension) to achieve micron-scale thin film construction, and possess good chemical compatibility to prevent conductive particle agglomeration and achieve controllable distribution on a flexible substrate, thereby modulating the device's strain response performance. These two synergistic design requirements present significant challenges to constructing ultrathin, breathable, and tunable soft strain sensors. Summary of the Invention

[0004] This invention aims to overcome the shortcomings of existing technologies and provide an ultrathin, breathable, soft strain sensor and its fabrication method. The process is simplified by using ink-free technology, particle embedding, and femtosecond laser etching. The fabricated sensor has micron-level thickness, tissue-like Young's modulus, and high breathability. Through conductive particle composition, morphology orientation design (0D-2D composite), and micropore topology optimization (circular / rhomboid / elliptical holes), the sensing performance can be systematically regulated to adapt to wearable medical applications.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A method for fabricating an ultrathin, breathable, soft strain sensor includes the following steps:

[0007] S1. Prepare a soft material substrate with a thickness of micrometers and a Young's modulus similar to soft tissue. The Young's modulus of the flexible substrate is achieved by selecting different polymer materials, including but not limited to: Ecoflex gel, Ecoflex 30 or DragonSkin 10.

[0008] S2. Based on the particle swallowing effect, conductive micro-nano particles are controllably embedded on the substrate to form a conductive permeation network, which is then encapsulated to obtain a soft strain sensor.

[0009] S3. A breathable microporous structure is fabricated on the soft strain sensor using laser etching technology, which imparts air permeability while improving sensitivity. The microporous structure includes, but is not limited to, various geometric configurations such as circular holes, rhomboid holes, and elliptical holes. Different geometric configurations of micropores induce differentiated local stress distributions in the soft strain sensor, thereby achieving adjustable sensing performance.

[0010] Further, step S1 specifically includes: laminating a PET / PVA composite film onto the surface of a silicon wafer substrate; performing plasma surface treatment on the laminated structure to enhance its surface activity; subsequently spin-coating a liquid silicone rubber precursor onto the treated composite film surface; and finally curing the precursor by heating in an oven to form the desired soft material substrate.

[0011] Furthermore, in step S1, by precisely controlling the thickness of the spin-coated liquid silicone rubber precursor, the thickness of the resulting soft material substrate and encapsulation layer can be directly adjusted, thereby regulating the overall thickness of the sensor; at the same time, by selecting liquid silicone rubber materials with different Young's modulus ranges as the substrate, the overall Young's modulus of the soft strain sensor can be adjusted accordingly.

[0012] Further, step S2 includes: coating carbon nanotubes, a mixture of carbon nanotubes and silver microparticles, or silica microspheres onto the soft material substrate, and embedding the corresponding carbon nanotube conductive layer, carbon nanotube / silver mixture conductive layer, or silica layer based on the particle swallowing effect; performing magnetron sputtering on the silica layer to form a gold conductive layer; and coating liquid metal electrodes at both ends of the three conductive channels to form a parallel structure.

[0013] Furthermore, in step S2, the parallel circuit structure is spin-coated and encapsulated using a liquid silicone rubber precursor, and then placed in an 80°C oven for 5 minutes to cure the encapsulation layer completely.

[0014] Furthermore, in step S2, the thickness of the resulting encapsulation layer is directly adjusted by precisely controlling the thickness of the spin-coated liquid silicone rubber precursor to regulate the overall thickness of the sensor. At the same time, the modulus of the encapsulation layer is adjusted accordingly by selecting liquid silicone rubber materials with different Young's modulus ranges as the encapsulation layer, so as to optimize the modulus matching of the soft strain sensor, reduce the hysteresis effect and improve stability.

[0015] Furthermore, in step S3, a microstructure of a circular hole array is controllably fabricated on the soft strain sensor using femtosecond laser etching technology to construct the required air-permeable channels.

[0016] Furthermore, the aperture of the circular aperture array is 105-133 μm, and the aperture spacing is 195-223 μm. Increasing the aperture can improve the air permeability of the soft strain sensor, but at the same time it will reduce the effective area of ​​the conductive path, resulting in an increase in the initial resistance of the sensor and a reduction in the strain measurement range.

[0017] An ultrathin, breathable, soft strain sensor was prepared using the method described above.

[0018] In summary, the present invention has the following advantages:

[0019] An ultrathin, breathable, soft strain sensor was fabricated: based on particle engulfment printing technology, micro- and nanoparticles were directly and controllably embedded in a soft material substrate to form a conductive layer, eliminating the need for solvents and avoiding complex hydrodynamic behavior, thus enabling the fabrication of an ultrathin sensor. A microporous array was etched using femtosecond laser technology, simultaneously optimizing key performance parameters such as device permeability and sensitivity. By selecting substrate and encapsulation layer materials with different Young's moduli, the overall modulus of the sensor can be adjusted, achieving ultra-soft mechanical properties while ensuring stability and low hysteresis, and imparting surface adhesion.

[0020] A series of sensors with different performance were controlled: Based on particle engulfment printing technology, a conductive network with controllable strain response was successfully constructed on an ultrathin low-modulus soft substrate; this method can precisely control the core performance parameters of the sensor, such as sensitivity, strain limit and hysteresis, to meet the differentiated detection needs of different parts of the human body for sensitivity and strain range; at the same time, the breathable holes constructed by laser etching significantly improved the breathability of the device and further optimized its overall sensing performance. Attached Figure Description

[0021] Figure 1 This refers to the ultrathin, breathable, soft strain sensor based on particle phagocytosis described in the embodiments of the present invention.

[0022] Figure 2 This is a schematic diagram of the fabrication process of the ultrathin, breathable, soft strain sensor described in an embodiment of the present invention.

[0023] Figure 3 This is a microscope image of the thickness of the ultrathin sensor described in an embodiment of the present invention.

[0024] Figure 4 This is a stretched schematic diagram of the carbon nanotube conductive layer sensor based on the geometric effect sensing mechanism described in an embodiment of the present invention.

[0025] Figure 5 This is a tensile schematic diagram of the silicon dioxide / gold composite conductive layer sensor based on the crack propagation sensing mechanism described in an embodiment of the present invention.

[0026] Figure 6This is a schematic diagram of the femtosecond laser processing structure of the sensor permeable micropore array described in an embodiment of the present invention.

[0027] Figure 7 This is a microscope image of the crack propagation morphology of the sensor of the femtosecond laser-processed permeable micropore array described in the embodiment of the present invention under tension.

[0028] Figure 8 The graph shows the measured data of Young's modulus of different soft material substrates described in the embodiments of the present invention.

[0029] Figure 9 This is a graph showing the 90° peel test data of the adhesive substrate material and skin described in the embodiments of the present invention.

[0030] Figure 10 The following are graphs of air permeability test data in the embodiments of the present invention: (a) is a graph showing the change of water content in glass bottles sealed with different materials over time; (b) is a graph showing the water vapor transmission rate of different materials.

[0031] Figure 11 This is a graph showing the change in relative resistance over time for a carbon nanotube and silver mixed component sensor of different thicknesses as described in an embodiment of the present invention.

[0032] Figure 12 The graph shows the relative resistance of the carbon nanotube and silver mixed component sensor with laser-etched and non-etched micropore arrays as described in the embodiments of the present invention, as a function of time.

[0033] In the picture:

[0034] 1-Silica / gold composite conductive layer, 2-Circular hole array, 3-Carbon nanotube / silver mixture conductive layer, 4-Soft material substrate, 5-Carbon nanotube conductive layer. Detailed Implementation

[0035] This invention aims to provide a performance-controllable, ultra-thin, breathable, soft strain sensor based on particle engulfment printing. Based on particle engulfment behavior, without the need for ink, micro / nano particles can be directly embedded into a solidified soft material driven by surface energy. By combining the Young's modulus control of the soft material substrate and encapsulation layer material, ultra-softening and customized interface adhesion are achieved without affecting the sensor's electrical and mechanical properties. Through conductive particle composition, morphology orientation design (0D-2D composite), and micropore topology optimization (circular / rhomboid / elliptical holes), the sensor's performance can be systematically controlled, achieving ultra-conformal contact and breathability with the skin. This reduces motion artifacts, improves monitoring accuracy and stability, and enhances wearing comfort. Furthermore, it can meet the differentiated detection needs of different parts of the human body for varying sensitivity and strain ranges.

[0036] The present invention will now be described in further detail.

[0037] like Figure 3 As shown, a method for fabricating an ultrathin, breathable, soft strain sensor includes the following steps:

[0038] S1. Preparation of a soft material substrate 4 with a micron-thickness and a Young's modulus similar to soft tissue: A PET (polyethylene terephthalate) and PVA (polyvinyl alcohol) composite film is coated on a silicon wafer substrate. The surface of the composite film is cleaned by plasma cleaning. Then, a layer of Ecoflex gel A and B glue (or other liquid silicone rubber precursors such as Ecoflex 30) prepared in a 1:1 weight ratio is spin-coated onto the silicon wafer substrate covered with the PET and PVA composite film. The substrate is then placed in an 80°C oven for curing for 5 minutes to obtain the soft material substrate 4.

[0039] S2. Based on the particle engulfment effect, conductive micro- and nano-particles are controllably embedded on the soft material substrate 4 to form a conductive permeation network, which is then encapsulated to obtain a soft strain sensor.

[0040] Specifically, using a mask, micro-nano particles are coated on the soft material substrate 4, allowing the micro-nano particles to densely enter the soft material substrate 4 through the particle phagocytosis effect and form a conductive layer. Liquid metal electrodes are coated at both ends of the conductive channel, and wires are connected to the liquid metal electrodes.

[0041] The soft material substrate 4, the conductive layer and the liquid metal electrode were spin-coated and encapsulated using a liquid silicone rubber precursor, and then placed in an 80°C oven for 5 minutes to cure the encapsulation layer.

[0042] S3. Using laser etching technology, a permeable channel is constructed on the soft strain sensor.

[0043] Specifically, a femtosecond laser cutting machine is used to etch a micro-hole array onto the soft strain sensor. The micro-hole array can include various shapes such as circular holes, rhomboid holes, and elliptical holes. Different geometric configurations of micro-holes induce differentiated local stress concentration effects, thereby enabling on-demand customization of the sensor's strain sensitivity and operating range.

[0044] This embodiment employs a circular aperture array 2, with aperture diameters of 105-133 μm and aperture spacing of 195-223 μm, resulting in an ultra-thin, breathable, soft strain sensor. Larger apertures improve the sensor's breathability but reduce the effective cross-sectional area of ​​the conductive path, leading to increased initial resistance and a decreased strain range.

[0045] This invention utilizes particle engulfment technology to controllably embed micro / nano particles within a soft matter substrate 4. The micro / nano materials are spontaneously absorbed by the polymer matrix of the soft matter substrate 4, thus avoiding the thickness limitations caused by ink viscosity and the limitations on electrical and mechanical properties caused by the concentration and agglomeration of conductive fillers in traditional processes. The overall thickness of the soft strain sensor can be adjusted by regulating the thickness of the spin-coated liquid silicone rubber precursor, enabling the fabrication of ultrathin soft strain sensors with a thickness of approximately 20 μm. This process simultaneously eliminates the risk of functional particle agglomeration, ensuring uniformity of electrical performance and preventing local differences in electrical performance or decreased conductivity. It also avoids the reduction in mechanical properties and geometric deformation or dissolution of the manufacturing structure due to chemical asymmetry between components. The processing is easy to control, and the preparation steps are simple and convenient.

[0046] The sensor of this invention is only 20μm thick, and no inverted cone shape will appear when the circular hole array 2 of the soft strain sensor is laser etched, which will not adversely affect the conductivity of the sensor. Due to the dense particle engulfment on the soft material substrate 4, the circular hole array 2 will not only not seriously affect its conductivity, but also further improve the sensitivity of the sensor due to stress concentration. The selection of a low Young's modulus substrate enables the soft strain sensor to achieve super-fit and breathability with the skin, reducing motion artifacts. Good breathability can ensure that the sweat secreted by human skin can evaporate into the air, avoiding discomfort caused by sweat accumulation, improving the accuracy and stability of monitoring and wearing comfort.

[0047] Traditional sensors require mixing conductive fillers and polymer solutions and then curing them. Since the conductive fillers are not dense enough to be absorbed by particles, laser drilling arrays would greatly reduce their electrical performance. In addition, traditional sensors are relatively thick, and drilling holes can easily result in inverted cone shapes, affecting the conductivity of the sensor. Therefore, it is difficult to improve the sensor sensitivity and permeability through circular hole arrays 2.

[0048] Traditional sensors based on rigid materials (such as metal foil) struggle to adhere to non-planar surfaces and are prone to failure under large deformation conditions, limiting their application in wearable devices. With the rapid development of wearable devices, electronic skin, and medical monitoring, higher demands are being placed on sensors for flexibility, thinness, breathability, and biocompatibility. Ultra-thin, breathable, soft strain sensors can closely conform to the skin or complex curved surfaces, avoiding the discomfort and signal distortion caused by the large size and high rigidity of traditional rigid sensors, thus reducing wearing discomfort. For example, the medical field requires real-time monitoring of human physiological signals (such as pulse and joint movement), but traditional sensors cannot meet the requirements for comfort and long-term wear. The diversity of human physiological signals places differentiated demands on strain sensor performance. Micro-strain signal detection (such as pulse and muscle micro-movements) requires sensors with ultra-high sensitivity and the ability to detect minute strains; medium-strain range monitoring (such as respiration and facial expressions) needs to cover a medium strain range while maintaining a certain level of sensitivity; and large-strain scenarios (such as joint bending and movement posture) require sensors that can withstand large strains without failure. Therefore, it is very important to propose a general soft strain sensor manufacturing technology to realize differentiated customization of sensor monitoring for different parts of the human body, and to provide a technical foundation for personalized needs in fields such as medical and health monitoring and intelligent robots.

[0049] This invention enables the controllable embedding of different micro / nanoparticles onto a soft material substrate. Through conductive particle composition, morphological orientation design (0D-2D composite), and micropore topology optimization (circular / rhomboid / elliptical holes), it achieves a spectrum of tunable sensing performance, adapting to multi-dimensional application scenarios such as epidermal electronics and wearable medical devices. Finally, by connecting conductive layers with different properties in parallel, a three-segment adjustable universal sensor is achieved, enabling differentiated customization for sensor monitoring of different parts of the human body.

[0050] Specifically, in this embodiment, S2 includes the following steps: coating carbon nanotubes, a mixture of carbon nanotubes and silver, and silica spheres onto a soft material substrate 4 to obtain a carbon nanotube conductive layer 5, a carbon nanotube and silver mixture conductive layer 3, and a silica layer; using a mask to block the remaining parts except the silica layer, performing magnetron sputtering gold conductive treatment on the silica layer to form a silica / gold composite conductive layer 1; and using liquid metal electrodes to connect the carbon nanotube conductive layer 5, the carbon nanotube / silver mixture conductive layer 3, and the silica / gold composite conductive layer 1 to form a parallel circuit.

[0051] The conductive layers prepared using three different micro / nanoparticles exhibit different conductivity, strain range, and sensitivity:

[0052] The silicon dioxide / gold composite conductive layer 1 formed after gold plating of silicon dioxide layer can also produce cracks under small strain. It has a small strain range and high sensitivity under small strain (about 1%), making it suitable for detecting weak physiological signals such as pulse.

[0053] The carbon nanotube / silver hybrid conductive layer 3 has high sensitivity and a wide strain range. It is particularly sensitive under moderate strain (about 10%), making it suitable for detecting respiration.

[0054] The carbon nanotube conductive layer 5 has the lowest sensitivity. Under large strain (about 50%), it has low sensitivity but a wide detection range, making it suitable for detecting joint motion.

[0055] By connecting these three conductive layers in parallel, multiple detection devices with different sensitivities can be obtained, which can be applied to different detection scenarios, such as pulse, respiration, and joint movement detection, greatly improving the application range and versatility.

[0056] like Figure 1 The image shows an ultrathin, breathable, soft strain sensor, which was prepared using the method described above.

[0057] In this embodiment, the ultrathin, breathable, soft strain sensor comprises a soft material substrate 4, a carbon nanotube conductive layer 5, a carbon nanotube / silver hybrid conductive layer 3, a silicon dioxide / gold composite conductive layer 1, and a silicone encapsulation layer. After the sensor is encapsulated and cured, a circular hole array 2 is laser-etched to obtain the final ultrathin, breathable, soft strain sensor.

[0058] Among them, the carbon nanotube conductive layer 5, the carbon nanotube / silver mixture conductive layer 3, the silicon dioxide / gold composite conductive layer 1, and the silicone encapsulation layer are connected by a liquid metal electrode (not shown in the figure) to form a parallel circuit, which can form multiple devices with different sensitivities and can be applied to different detection scenarios at the same time, such as pulse, respiration, and joint movement detection.

[0059] like Figure 3 The image shown is a microscope image of the thickness of the ultrathin sensor, demonstrating that an ultrathin soft strain sensor can be easily fabricated using the method described above.

[0060] like Figure 4 The diagram shows a stretched schematic of a sensor based on a geometric effect sensing mechanism, which is controlled by a carbon nanotube conductive layer 5. The sensor based on the geometric effect sensing mechanism has a large strain range and low sensitivity, and can be used to detect human joint movements.

[0061] like Figure 5 The diagram shows a tensile schematic of a sensor based on the crack propagation sensing mechanism, which is controlled by the silicon dioxide / gold composite conductive layer 1. The sensor based on the crack propagation sensing mechanism has a small strain range and high sensitivity, and can be used to detect human pulse.

[0062] like Figure 6 The diagram shows a laser-etched circular hole array, which can create a regular circular hole array 2, and the conductive path is clearly visible.

[0063] like Figure 7 The image shown is a microscope image of a stretched ultrathin sensor after laser etching. Laser etching causes stress concentration, and the cracks are mainly concentrated between the micropores, which improves the sensor's sensitivity.

[0064] like Figure 8 The diagram shows the Young's modulus of different substrates and encapsulation layers. By adjusting the Young's modulus of the substrate and encapsulation layer, an ultra-soft and low-hysteresis soft strain sensor can be made.

[0065] like Figure 9 The image shows data from a 90° peel test on skin with Ecoflex gel of different thicknesses. Choosing an adhesive substrate allows for better conformal contact between the sensor and the skin, improving detection accuracy.

[0066] like Figure 10 In the figure, (a) shows the air permeability test chart of different materials. The test results show that the ecoflex gel encapsulated with 110μm laser hole array reduces the water content in the test bottle the fastest and has the best air permeability. (b) shows the water vapor transmission rate test chart of different materials. The ecoflex gel encapsulated with 110μm laser hole array has the best air permeability, even exceeding that of cotton cloth, quick-drying clothing fabric, and PDMS material, which is considered to have good air permeability.

[0067] like Figure 11 The figures show the sensitivity profiles of the carbon nanotube and silver microparticle mixtures for sensors with thicknesses of 2 mm and 20 μm. The test results indicate that reducing the sensor thickness significantly improves sensitivity under larger strains, but the improvement is not significant under smaller strains. By varying the mixing ratio of carbon nanotubes and silver microparticles, a series of sensors with different sensitivities were obtained.

[0068] like Figure 12 The image shows test results of a 110μm circular hole array etched by femtosecond laser and a 20μm thick sensor without etching. The test results show that the sensor sensitivity is significantly improved after laser etching. Even under ultra-small strain (1%), it achieves high sensitivity (GF≈100) and has the ability to test weak physiological signals (such as pulse, respiration, etc.).

[0069] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A method for fabricating an ultrathin, breathable, soft strain sensor, characterized in that: Includes the following steps, S1. Prepare a soft material substrate with a thickness of micrometers and a soft tissue-like Young's modulus; S2. Based on the particle engulfment effect, conductive micro- and nano-particles are controllably embedded on the soft material substrate to form a conductive permeation network, which is then encapsulated to obtain a soft strain sensor. S3. Use laser etching technology to construct air-permeable channels on the sensor.

2. The preparation method according to claim 1, characterized in that, S1 includes: laminating a PET / PVA composite film onto the surface of a silicon wafer substrate; performing plasma surface treatment on the laminated structure to enhance its surface activity; subsequently spin-coating a liquid silicone rubber precursor onto the treated composite film surface; and finally curing the precursor by heating in an oven to form the desired soft material substrate.

3. The preparation method according to claim 2, characterized in that: In S1, by precisely controlling the thickness of the spin-coated liquid silicone rubber precursor, the thickness of the resulting soft material substrate can be directly adjusted, thereby regulating the overall thickness of the sensor; at the same time, by selecting silicone rubber materials with different Young's modulus ranges as the substrate, the overall Young's modulus of the soft strain sensor can be adjusted accordingly. Alternatively, a soft substrate with self-adhesive properties can be selected to make the sensor adhesive.

4. The preparation method according to claim 1, characterized in that, S2 includes: coating the surface of the soft material substrate with conductive particles of different compositions or morphologies to construct a differentiated conductive permeation network, thereby obtaining a soft strain sensor with gradient sensing performance.

5. The preparation method according to claim 4, characterized in that: Carbon nanotubes, a mixture of carbon nanotubes and silver microparticles, or silica microspheres are coated onto the soft material substrate, and corresponding carbon nanotube conductive layers, carbon nanotube / silver mixture conductive layers, or silica layers are embedded based on the particle swallowing effect; the silica layers are magnetron sputtered to form gold conductive layers; liquid metal electrodes are coated at both ends of the three conductive layers to form a parallel structure.

6. The preparation method according to claim 1, characterized in that: The encapsulation in S2 includes spin-coating a liquid silicone rubber precursor onto the surface of a conductive layer, and then placing the spin-coated sample in an oven for heating and curing to form an encapsulation structure.

7. The preparation method according to claim 6, characterized in that: In S2, the thickness of the encapsulation layer is directly controlled by precisely controlling the thickness of the spin-coated liquid silicone rubber precursor to adjust the overall thickness of the sensor. At the same time, the modulus of the encapsulation layer is adjusted accordingly by selecting liquid silicone rubber materials with different Young's modulus ranges as the encapsulation layer, so as to optimize the modulus matching of the soft strain sensor, reduce the hysteresis effect and improve the stability.

8. The preparation method according to claim 1, characterized in that: The air-permeable channel in S3 is constructed by processing a micro-hole array on a soft strain sensor using a femtosecond laser cutting machine. The micro-hole array includes at least one geometric configuration among round holes, rhomboid holes, or elliptical holes.

9. The preparation method according to claim 8, characterized in that: The laser-etched micro-hole array is a circular hole array with a hole diameter of 105-133μm and a hole spacing of 195-223μm.

10. An ultrathin, breathable, soft strain sensor, characterized in that: It is prepared by the preparation method according to any one of claims 1-9.

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