A strain-isolated, breathable, stretchable substrate and its preparation method

Abstract

This invention relates to a strain-isolated, breathable, stretchable substrate and its preparation method. The preparation method includes the following steps: S1, mixing tetrahydrofuran, dimethylformamide, and polyurethane to obtain a PU spinning solution; S2, electrospinning the PU spinning solution to obtain a PU fiber film; S3, mixing isobornyl acrylate, benzyl acrylate, and a photocurable resin, adding a photoinitiator, and stirring in a light-shielded environment to obtain a rigid polyacrylate precursor solution and a flexible polyacrylate precursor solution, respectively; S4, customizing a hollow pattern template; S5, printing the rigid and flexible polyacrylate precursor solutions onto the PUS according to the positions of electrical components and wires pre-reserved in the hollow pattern template, based on a specific PU:PA ratio, and photocuring under ultraviolet light to obtain the strain-isolated, breathable, stretchable substrate. The resulting substrate has programmable strain selectivity and stretchable breathability.

Description

Technical Field

[0001] This invention belongs to the field of breathable electronic integration technology, specifically relating to a strain-isolated breathable stretchable substrate and its preparation method. Background Technology

[0002] With the development of flexible electronics and wireless communication technologies, wearable electronic systems have shown broad application prospects in fields such as continuous physiological monitoring, health management, and chronic disease care. These systems typically require the integration of multiple functional components, including sensors, energy storage devices, signal processing units, and wireless communication modules, onto a single substrate. Therefore, the mechanical properties, structural stability, and breathability of the supporting substrate have a significant impact on the reliability and wearing comfort of the devices.

[0003] Current electronic systems mostly use printed circuit boards (PCBs) as a support platform, but their high modulus and insufficient flexibility make it difficult to achieve a good mechanical fit with human skin. In recent years, elastic polymers such as polybutylene terephthalate (Ecoflex) and polydimethylsiloxane (PDMS) have been used as flexible electronic substrates. However, these materials are usually dense in structure and have poor breathability, which can easily affect comfort when attached to the skin for a long time. At the same time, stress concentration is easily generated during repeated stretching, affecting the mechanical stability of the device.

[0004] To improve breathability, researchers have proposed using porous fiber substrates such as electrospun or woven fibers. However, when rigid functional units such as batteries and chips are integrated into the system, strain mismatch easily occurs between the soft substrate and the rigid device, leading to interface failure or device damage. Furthermore, existing methods for achieving strain isolation through localized stiffening or filling materials often reduce the breathability of the substrate. Therefore, there is an urgent need to develop a stretchable electronic substrate that combines high tensile strength, high breathability, and a stable strain isolation structure to meet the application requirements of multifunctional integrated wearable electronic devices. Summary of the Invention

[0005] The purpose of this invention is to provide a strain-isolated, breathable, stretchable substrate and its preparation method, aiming to solve the problems that existing substrates cannot simultaneously possess high tensile strength, high breathability, and strain mismatch with rigid devices.

[0006] The first objective of this invention is to provide a method for preparing a strain-isolated, breathable, stretchable substrate, comprising the following steps: S1. By setting the addition ratio, tetrahydrofuran, dimethylformamide and polyurethane (PU) are mixed and stirred to obtain PU spinning solution; S2. Electrospin the PU spinning solution obtained in step S1 to obtain a PU fiber film. S3. After mixing isoborneol acrylate, benzyl acrylate and photocurable resin according to different set ratios, a photoinitiator is added and the mixture is stirred in a light-proof environment to obtain rigid polyacrylate precursor liquid (Stiff-PAp) and soft polyacrylate precursor liquid (Soft-PAp). S4. Convert the standardized custom pattern layout into a laser processing file, use a CO2 power controllable laser system to process the template material, selectively remove part of the template material to obtain a customized hollow pattern template. S5. According to a specific mass ratio of PU film to polyacrylate (PA, which is formed by photopolymerization of PAp), the rigid polyacrylate precursor liquid is printed on the electrical component area reserved in the hollow pattern template on the PU fiber film (PUS), and the soft polyacrylate precursor liquid is printed on the reserved wire area; after ultraviolet curing, a strain-isolated breathable stretchable substrate is obtained.

[0007] Compared with existing technologies, this invention features programmable strain selectivity and stretchable breathability. Based on a swelling-induced in-situ polymerization strategy, acrylate monomers are infiltrated into the electrospun PU fiber network, significantly enhancing the load transfer capacity within the fiber through molecular chain entanglement and hydrogen bonding, thereby improving the mechanical strength and tensile fracture resistance of the substrate. By controlling the ratio of isobornyl acrylate (IBOA) and benzyl acrylate (BA), the local modulus of the fiber can be programmably controlled, thus constructing a strain isolation structure that combines rigid islands and flexible bridges. Simultaneously, this process maintains the interconnected porous structure of the electrospun fiber membrane, preserving continuous gas transport channels while achieving modulus spatial control, thus combining excellent mechanical stability and breathability. Furthermore, the use of a CO2 power controllable laser system for selectively cutting pattern templates improves the precision and personalization of circuit design, and the process is simple and scalable.

[0008] In one possible implementation, the mass fraction of polyurethane in the PU spinning solution is 20-25 wt%.

[0009] In one possible implementation, the mixing temperature in step S1 is 15-25°C, and the time is 8-10 h.

[0010] Compared with the prior art, the longer stirring time of the present invention can ensure that all components are fully mixed, so that the polyurethane can be evenly distributed. At the same time, this temperature range provides sufficient fluidity while avoiding unnecessary chemical reactions, ensuring that the polyurethane can be fully dissolved in the mixed solution of tetrahydrofuran and dimethylformamide.

[0011] In one possible implementation, step S2, prior to electrospinning, further includes an ultrasonic treatment of the PU spinning solution, with an ultrasonic frequency of 20-80 kHz and an ultrasonic duration of 20-25 min.

[0012] In one possible implementation, the injection rate of electrospinning in step S2 is 0.6~0.8 mL / h, the metal needle specification is 18G, the applied voltage is 12 kV, and the collection distance is 15 cm.

[0013] Compared with the prior art, the present invention uses the above parameters to effectively degas the PU spinning solution, thereby removing dissolved gases from the solution and avoiding interference during the subsequent liquid discharge process of the electrospinning nozzle, thus achieving higher precision and smoothness of the PU fiber film.

[0014] In one possible implementation, in step S3, diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide (TPO) is generally used as a photoinitiator, and bifunctional aliphatic polyacrylate (AUD) is used as a photocurable resin. For rigid polyacrylate precursor liquid, the mass ratio of isobornyl acrylate, benzyl acrylate, AUD and TPO is (45-55):(15-25):30:1; for flexible polyacrylate precursor liquid, the mass ratio of isobornyl acrylate, benzyl acrylate, AUD and TPO is (15-25):(45-55):30:1.

[0015] Compared with existing technologies, this invention uses 50 wt% IBOA as the core monomer to prepare a rigid polyacrylate precursor (Stiff-PAp). Utilizing the rigid ring structure of IBOA, the chain segment constraint and overall stiffness of the material's rigid regions are effectively improved, making this precursor ink suitable for the fabrication of structural components with high mechanical stability requirements, particularly for "island" structures. Conversely, 50 wt% BA is used as the core monomer to prepare a soft polyacrylate precursor (Soft-PAp). The flexible chains provided by BA endow the material with excellent strain adaptability, significantly improving its energy absorption capacity and impact resistance. Simultaneously, the high BA content imparts excellent flexibility and compliance, making it suitable for structures such as "bridges." By adjusting the proportions of these materials, uniform stress distribution can be achieved under stress or tension, reducing localized stress concentration.

[0016] In one possible implementation, the photoinitiator in step S3 is TPO.

[0017] Compared with existing technologies, TPO is a highly efficient photoinitiator that decomposes under ultraviolet (UV) light to generate benzoyl and phosphoryl diradicals, which efficiently initiate the free radical polymerization of IBOA, BA, and AUD. At the same time, TPO has a photobleaching effect, which can achieve deep curing with low yellowing. It has excellent compatibility with all components of the precursor solution and leaves no obvious residue after curing, ensuring the crosslinking uniformity and mechanical synergy of soft and hard island bridge structures, and ultimately improving the device integration and stability.

[0018] In one possible implementation, the stirring temperature in step S3 is 15-25°C, and the stirring time is 5-8 h.

[0019] Compared with existing technologies, this invention uses a stirring temperature of 15-25℃ for light-shielding stirring. This temperature range prevents premature and unnecessary polymerization reactions while providing sufficient fluidity for mixing. The light-shielding environment effectively blocks light energy input, inhibits polymerization in non-target areas, and ensures that TPO remains inert during the stirring stage, thus ensuring the fluidity and processability of the precursor liquid. At the same time, setting a stirring time of 5 hours avoids the formation of local high-viscosity regions in AUD due to its intrinsically high melt viscosity, ensuring that the photoinitiator TPO is uniformly dispersed in the continuous phases of IBOA, BA, and AUD. This ensures that the subsequent in-situ UV photopolymerization reaction starts synchronously and uniformly throughout the entire system, achieving consistency in crosslinking density and mechanical properties of the soft and hard island bridge structures.

[0020] In one possible implementation, the wavelength of the ultraviolet light in step S5 is 365 nm, and the photocuring time is 10-15 s.

[0021] A second objective of this invention is to provide a strain-isolated, breathable, stretchable substrate prepared by the above-described preparation method. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the preparation process and microstructure of a strain-isolated, breathable, stretchable substrate according to the present invention (S-PU in the figure represents the soft segment of PU itself, and H-PU represents the hard segment of PU itself). Figure 2 (a) Photographs of the PU, PU@PAp and PU@PA films prepared in Example 1 (the upper layer is PU@Soft-PA, the lower layer is PU@Stiff-PA, and they are shown from left to right as PU, PU@PAp and PU@PA). Figure 2 (b) Scanning electron microscope (SEM) images of in-situ polymerized Soft-PA (yellow box on the left) and Stiff-PA (orange box on the right) PU films; Figure 2 (c) is a high-magnification SEM image of the PU@Soft-PA interface; Figure 2 (d) is a high-magnification SEM image of the PU@Stiff-PA interface; Figure 3 Line graph showing the air permeability of PU films with different PA contents; Figure 4 (a) shows the stress-strain curves of PUS and SISS; Figure 4 (b) shows the resistance change (ΔR / R0) of a liquid metal interconnect circuit on the PUS and SISS under tensile strain. Figure 5 (a) Schematic diagram of a stretchable and breathable integrated system worn on the back for human body detection; Figure 5 (b) is a schematic diagram of the key functional components of the stretchable and breathable integrated system; Figure 5 (c) is a schematic diagram of the stable electrical performance of the integrated system under 30% biaxial tensile strain. Detailed Implementation

[0023] like Figure 1 As shown, this invention discloses a method for preparing a strain-isolated, breathable, stretchable substrate. A PU fiber substrate is prepared by electrospinning, and PAp is introduced using a masking method. In-situ UV curing forms a hydrogen-bonded cross-linked network, thereby precisely constructing a synergistic structure of breathable rigid functional islands and flexible interconnecting bridges. This structured composite design achieves both stretchability and breathability of the substrate layer, ensuring strain isolation and electrical stability of the entire system. Specifically, the method includes the following steps: S1. Preparation of PU spinning solution: Tetrahydrofuran and dimethylformamide are mixed at a volume ratio of 1:(0.8-1.2); polyurethane particles are added using the above mixed solvent as the solvent, and the mixture is mechanically stirred at 15-25℃ for 8-10 h to prepare a PU spinning solution with a PU mass fraction of 20-25 wt%.

[0024] S2. Preparation of PU fiber film: The PU spinning solution obtained in step S1 is subjected to water bath ultrasonic treatment and then electrospinned using an electrospinning device to obtain a PU fiber film; the frequency of water bath ultrasonic treatment is 20-80 kHz, the ultrasonic treatment duration is 20-25 min, the electrospinning is uniaxial electrospinning, the injection speed is 0.6~0.8 mL / h, the metal needle specification is 18G, the applied voltage is 12 kV, and the collection distance is 15 cm.

[0025] S3. Preparation of in-situ photocurable printing ink: Isobornyl acrylate (IBOA) and benzyl acrylate (BA) monomers are mixed with photocurable resin (AUD) according to the set ratio. A photoinitiator (TPO) is then added, and the mixture is mechanically stirred in a light-shielded environment to obtain rigid polyacrylate precursor liquid (Stiff-PAp) and soft polyacrylate precursor liquid (Soft-PAp). The formulation for Stiff-PAp is as follows: the mass ratio of isobornyl acrylate, benzyl acrylate, photocurable resin, and photoinitiator is (45-55):(15-25):30:1. The formulation for Soft-PAp is as follows: the mass ratio of isobornyl acrylate, benzyl acrylate, photocurable resin, and TPO is (15-25):(45-55):30:1. The mechanical stirring parameters are as follows: temperature 15-25℃, time 5-8 h.

[0026] S4. Preparation of patterned mask: First, the pattern layout is customized as needed in the program and converted into a laser processing file. Then, release cellophane is used as the mask material and placed on the processing table. A CO2 laser system with adjustable power is used to selectively cut it to obtain a customized hollow pattern template. This allows for precise pattern cutting under a 15-25 W low-power CO2 laser, avoiding mask ablation and deformation, improving the accuracy of the mask pattern. It also utilizes the electrostatic effect between the release cellophane and PUS to achieve adhesion, avoiding the contamination of the substrate caused by traditional adhesive layer fixation. At the same time, it ensures that the mask and the substrate are bonded without gaps, preventing ink seepage.

[0027] S5. Using the hollow pattern templates designed in S4, the Stiff-PAp and Soft-PAp prepared in S3 are printed onto the PU fiber film at the reserved positions for electrical components and wires, with a PU:PA mass ratio of 1:3. Under ultraviolet light, the various PA monomers in the precursor solution are induced to polymerize and cure on the PU film, finally obtaining a strain-isolated, breathable, stretchable substrate. The in-situ curing parameters under direct ultraviolet light are as follows: ultraviolet wavelength 365nm, curing time 10-15 s.

[0028] The final strain-isolated, breathable, stretchable substrate comprises a polyurethane (PU) fiber film, on which Stiff-PAp and Soft-PAp are selectively printed according to a designed pattern and then photopolymerized in situ to obtain a PU@PA composite. The composite portion obtained by printing Stiff-PAp, referred to as the PU@Stiff-PA portion, is used to support multifunctional integrated devices; the composite portion obtained by printing Soft-PAp, referred to as the PU@Soft-PA portion, is used to support interconnect conductive pathways. This achieves swelling-induced in-situ polymerization and local modulus control, constructing a strain-isolated structure that combines breathable rigid functional islands with flexible interconnect bridges, thereby improving device integration and stability.

[0029] The present invention will be further illustrated below through specific embodiments.

[0030] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention are described in detail below. It should be noted that the following embodiments are only used to illustrate the implementation methods and typical parameters of the present invention, and are not intended to limit the parameter range described in the present invention. Reasonable variations derived therefrom are still within the protection scope of the claims of the present invention.

[0031] It should be noted that the endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0032] Unless otherwise defined, all terms, symbols and other scientific terms used herein are intended to have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. All processing reagents are used as is. The raw materials include: tetrahydrofuran (THF), dimethylformamide (DMF), polyurethane (PU, Ispin), isobornyl acrylate (IBOA, Adamas-beta), benzyl acrylate (BA, Adamas-beta), bifunctional aliphatic polyacrylate (AUD, Ebecryl 8413, Allnex), and diphenyl (2,4,6-trimethylbenzoyl)phosphine oxide (TPO, Sigma-Aldrich).

[0033] Example 1 This embodiment provides a strain-isolated, breathable, stretchable substrate for a printed photopolymerizable island bridge structure, which is prepared by the following method: S1. Preparation of PU spinning solution: 4 mL of tetrahydrofuran, 4 mL of dimethylformamide and 1.838 g of polyurethane were mixed and mechanically stirred at 25 °C for 8 h to obtain PU spinning solution for electrospinning printing substrate film. S2. Preparation of PU fiber film: The PU spinning solution obtained in step S1 is ultrasonically treated in a water bath at a frequency of about 50 kHz for 20 min. Then, uniaxial electrospinning mode is adopted, using an 18 G metal needle, with the injection flow rate set to 0.7 mL / h and the voltage set to 12 kV. PUS for use as a substrate layer is obtained by electrospinning. S3. Preparation of photocurable printing inks: Mix them according to the mass ratios of IBOA:BA:AUD:TPO = 50:20:30:1 and 20:50:30:1, and mechanically stir for 5 h in a light-shielding environment at 25 ℃ to obtain Stiff-PAp and Soft-PAp respectively. S4. Preparation of patterned mask: First, the standardized custom pattern layout is converted into a laser processing file. Release cellophane is used as the mask material. The release cellophane is placed on the laser stage and a CO2 laser with adjustable power is used to selectively cut the cellophane according to the program file to obtain a programmable custom patterned mask. S5. The Stiff-PAp and Soft-PAp prepared using S3 are selectively printed on the PUS prepared in S2 at predetermined positions using the mask prepared according to the design in S4. The printed Stiff-PAp and Soft-PAp are subjected to in-situ photocuring reaction for 10 s under 365 nm ultraviolet light to finally obtain the strain-isolated, breathable, stretchable substrate SISS.

[0034] The morphology of the SISS obtained in Example 1 was characterized. Figure 2 (a) Visually demonstrates the appearance of PU, PU@Soft-PA and PU@Stiff-PA. Figure 2 (b) shows the SEM images of PU@PA. The area selected by the yellow rectangle on the left is PU@Soft-PA, and the area selected by the orange rectangle on the right is PU@Stiff-PA. Both are continuous nanofiber mesh structures with uniform fiber arrangement and no obvious breaks, achieving excellent breathability and stretchability. Further high-magnification SEM images are shown below. Figure 2 As shown in (c) and (d).

[0035] Example 2 This embodiment investigates the effect of different PU / PA mass ratios on the air permeability of SISS, aiming to optimize material ratios through quantitative air permeability characterization to achieve the optimal synergy between mechanical and air permeability performance. This provides a performance basis for the subsequent application design of this invention. The specific characterization method is as follows: S1. Prepare PUS, Stiff-PAp and Soft-PAp according to the methods described in S1-S3 of Example 1; S2. Set PU / PA mass ratios of 1:0, 1:2, 1:2.5, 1:3, 1:3.5, and 1:4 respectively. Following the mask printing method described in S4 of Example 1, coat Stiff-PAp and Soft-PAp onto the electrical component area and wire area of ​​the PU film respectively. Perform in-situ photopolymerization reaction under 365nm ultraviolet light to obtain SISS samples with different PA contents. S3. Using a fully automatic air permeability tester (YG46IF, Wenzhou Fangyuan), the air permeability of SSISS samples with different ratios was tested. After multiple repeatability tests, the air permeability rate was characterized in mm / s. The test parameters were: temperature 25 ℃, test diameter 14 cm, and pressure difference 100 Pa.

[0036] Figure 3 Line graph showing the air transmittance of SISS with different PA contents (PU / PA = 1:x). Figure 3 As shown, the interconnected porous structure imparted by electrospinning gives pure PUS (x = 0) an air permeability of approximately 33 mm / s. With increasing PA content, the air permeability of SISS decreases controllably. Between x = 0 and 2, swelling allows PAp to penetrate the PU fibers, and in-situ polymerization maintains the porous structure, resulting in an air permeability essentially the same as pure PUS. At x = 4, excessive PA content leads to the closure of the PU fiber network pores, thereby blocking gas transport channels and causing the SISS air permeability to drop to approximately 0 mm / s.

[0037] This invention uses a PU / PA ratio of 1:3 to prepare SISS. While the substrate still has an air permeability of approximately 21 mm / s, its high PA content provides sufficient mechanical strength and modulus control. This allows the SISS of this ratio to meet the skin comfort requirements of wearable electronic devices for long-term wear, while also ensuring good mechanical stability and strain isolation, thus achieving synergistic optimization of mechanical properties and breathability.

[0038] Example 3 This embodiment characterizes the mechanical stretchability and electrical stability of the SISS, aiming to verify the superior performance of the synergistic structure of rigid islands and flexible bridges in terms of strain isolation and electrical stability by comparing SISS with pure PUS. The specific characterization method is as follows: S1. Prepare PUS, Stiff-PAp and Soft-PAp according to the methods described in S1-S3 of Example 1; S2. Set the PU / PA mass ratio to 1:3, and according to the mask printing method described in S4 of Example 1, coat the electrical component carrier area and the wire interconnection area of ​​the PU film with Stiff-PAp and Soft-PAp respectively, and carry out in-situ photocuring polymerization reaction under 365nm ultraviolet light to obtain SISS; S3. Uniaxial tensile tests were performed on the prepared SISS and the control sample PUS. After multiple repeatable experiments, the stress-strain data of SISS and PUS were recorded and curves were plotted. Figure 4 (a); S4. Using gallium indium alloy liquid metal (LM, EGaIn) as the interconnect wire material, it is integrated into the wire regions of SISS and PUS respectively by printing method to construct LM conductive path; S5. Characterize the electrical stability of the above SISS / PUS samples under tensile conditions: Apply uniaxial tension within the strain range of 0-500%, monitor and record the relative change in resistance (ΔR / R0) in real time, and after multiple repeatable tests, plot the resistance change curves of the LM interconnect circuit on the SISS and PUS under different tensile strains. Figure 4 (b).

[0039] like Figure 4 As shown in (a), compared to PUS, SISS can maintain a high fracture strain of nearly 600% and maintain an extremely low level of device resistance change within the strain range of 0-500%, achieving excellent strain isolation effect and electrical stability; Figure 4 As shown in (b), the LM circuit of PUS generates significant resistance fluctuations during tensile strain, and may even break and fail. SISS, relying on the island bridge strain isolation structure, can concentrate the strain in the flexible interconnect region, significantly reducing the deformation transmission in the rigid device bearing region, and enabling the LM interconnect circuit to maintain extremely low resistance changes.

[0040] Application example: This application example uses the prepared SISS substrate to construct a back-worn stretchable and breathable integrated system to verify its adaptability, mechanical stability, and multifunctional integration capabilities in real-world wearable scenarios: Based on the SISS prepared in Example 1, according to the customized circuit layout, LM interconnect circuits are mounted in the Soft-PA flexible bridge region, and multifunctional electronic devices are integrated in the Stiff-PA rigid island region to complete the assembly of the stretchable and breathable integrated system.

[0041] like Figure 5 As shown in Figure 5(a), this integrated system can be attached to clothing on the back of the body. Utilizing the excellent softness and breathability provided by the SISS, it can meet the wearability requirements for long-term physiological monitoring. As shown in Figure 5(b), this system achieves high-density integration of core functional components such as a wireless charging unit, zinc-ion battery, LM circuit stretching unit, and piezoresistive sensor on the SISS, verifying its ability to support and be compatible with complex electronic systems. Figure 5 As shown in (c), under simulated daily human activity and tensile strain, the integrated system still maintains a stable electrical connection and does not experience problems such as device detachment or wire breakage, thus enabling the wearable electronic system to operate reliably under human dynamic conditions.

[0042] While the present invention has been disclosed above, its scope of protection is not limited thereto. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention, and all such changes and modifications will fall within the scope of protection of the present invention.

Claims

1. A method for preparing a strain-isolated, breathable, stretchable substrate, characterized in that, Includes the following steps: S1. By setting the addition ratio, tetrahydrofuran, dimethylformamide and polyurethane are mixed and stirred to obtain PU spinning solution; S2. Electrospin the PU spinning solution obtained in step S1 to obtain a PU fiber film. S3. After mixing isoborneol acrylate, benzyl acrylate and photocurable resin according to different set ratios, add photoinitiator and stir in a light-proof environment to obtain rigid polyacrylate precursor liquid and soft polyacrylate precursor liquid respectively. S4. Convert the standardized custom pattern layout into a laser processing file, use a CO2 power controllable laser system to process the template material, selectively remove part of the template material to obtain a customized hollow pattern template. S5. The rigid polyacrylate precursor liquid and the soft polyacrylate precursor liquid are respectively printed and coated on the PU fiber film according to the positions of the electrical components and wires reserved in the hollow pattern template, and then photocured under ultraviolet light to obtain the strain-isolated breathable stretchable substrate.

2. The preparation method according to claim 1, characterized in that, In step S1, the PU spinning solution is prepared as follows: Tetrahydrofuran and dimethylformamide are mixed at a volume ratio of 1:(0.8-1.2); then polyurethane is added and stirred to prepare the PU spinning solution.

3. The preparation method according to claim 1 or 2, characterized in that, The polyurethane mass fraction of the PU spinning solution is 20-25 wt%.

4. The preparation method according to claim 3, characterized in that, The mixing temperature in step S1 is 15-25℃, and the time is 8-10 h.

5. The preparation method according to claim 1, characterized in that, Step S2, prior to electrospinning, also includes an ultrasonic treatment of the PU spinning solution, with an ultrasonic frequency of 20-80 kHz and an ultrasonic duration of 20-25 min.

6. The preparation method according to claim 1 or 5, characterized in that, In step S2, the injection rate of electrospinning is 0.6~0.8 mL / h, the metal needle specification is 18G, the applied voltage is 12 kV, and the collection distance is 15 cm.

7. The preparation method according to claim 1, characterized in that, In step S3, for the rigid polyacrylate precursor solution, the mass ratio of isoborneol acrylate, benzyl acrylate, photocurable resin and photoinitiator is (45-55):(15-25):30:1; for the flexible polyacrylate precursor solution, the mass ratio of isoborneol acrylate, benzyl acrylate, photocurable resin and photoinitiator is (15-25):(45-55):30:

1.

8. The preparation method according to claim 1, characterized in that, The stirring temperature in step S3 is 15-25℃, and the stirring time is 5 h.

9. The preparation method according to claim 1, characterized in that, In step S5, the wavelength of the ultraviolet light is 365 nm, and the photocuring time is 10-15 s.

10. A strain-isolated, breathable, stretchable substrate, characterized in that, It is prepared by the preparation method according to any one of claims 1-9.

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