Strain sensor with exercise monitoring and all-weather rehabilitation physiotherapy functions and preparation method and application thereof
By forming a functional layer with a micro-wrinkled structure on a flexible polymer nanocomposite sheet and combining it with a conductive network, the problem of poor sensor interface bonding is solved, realizing the functions of all-weather rehabilitation therapy and motion monitoring, which is suitable for industrial mass production.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-02
- Publication Date
- 2026-04-03
AI Technical Summary
Existing wearable electronic devices have shortcomings in motion monitoring and rehabilitation therapy functions, making it difficult to achieve all-day, long-term thermotherapy effects. Furthermore, the interface between flexible polymer materials and carbon-based conductive nanoparticle coatings is weak, resulting in poor stability of sensing and rehabilitation therapy functions.
A strain sensor with both motion monitoring and all-weather rehabilitation physiotherapy functions was prepared by combining flexible polymer nanocomposite sheets with conductive nanoparticles and forming a functional layer with micro-wrinkled structure through solvent swelling and oxidative polymerization reactions to enhance interfacial bonding. The conductive network was used to realize photothermal and electrothermal effects.
It achieves rapid heating and temperature uniformity of the sensor in all weather conditions, improves the sensor's functional durability and stability, is suitable for all-weather rehabilitation and physiotherapy, and has a simple and easy preparation method, suitable for industrial mass production.
Smart Images
Figure CN121782984A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of flexible sensor fabrication technology, specifically to a strain sensor that combines motion monitoring and all-weather rehabilitation therapy functions, its fabrication method, and its application. Background Technology
[0002] With the development of digitalization and people's increasing emphasis on health, research and development in the field of smart wearable technology is increasingly focusing on health monitoring and rehabilitation management of human physiological signals. However, most wearable electronic devices are currently limited to motion monitoring functions, lacking the ability to combine motion monitoring with rehabilitation therapy. Among various clinical treatments, physical thermotherapy can effectively treat arthritis and joint injuries, promoting blood circulation and relieving symptoms such as joint stiffness. However, achieving accurate monitoring, rapid heating, precise temperature regulation, and long-term stable treatment are key technical challenges that need to be addressed in the development of wearable physical thermotherapy devices. Reported flexible strain sensors for rehabilitation therapy typically utilize single photothermal or electrothermal properties for heating, which is insufficient for all-day, long-term thermotherapy.
[0003] Carbon-based conductive nanoparticles (such as carbon nanotubes, carbon nanofibers, and graphene) possess high thermal and electrical conductivity, as well as photothermal conversion efficiency. Applying a carbon-based conductive nanoparticle coating to the surface of flexible polymer materials using processes like dip-coating and coating can impart excellent photothermal and electrothermal properties to the flexible materials, enabling the fabricated flexible sensors to possess all-weather rehabilitation and therapeutic functions. However, the interfacial bonding between the flexible polymer material and its surface carbon-based conductive nanoparticle coating is relatively weak, which leads to poor stability in both sensing and rehabilitation / therapeutic functions. Summary of the Invention
[0004] To address the problems existing in the prior art, the purpose of this invention is to provide a strain sensor that combines motion monitoring and all-weather rehabilitation therapy functions.
[0005] Another object of the present invention is to provide a method for preparing the above-mentioned strain sensor.
[0006] Another object of the present invention is to provide applications of the above-mentioned strain sensor.
[0007] To achieve the above objectives, the present invention adopts the technical solution described below.
[0008] A strain sensor that combines motion monitoring and all-weather rehabilitation therapy functions consists of a flexible sensing substrate and electrodes; the flexible sensing substrate is composed of a functional layer with a micro-wrinkled structure and a thin sheet of flexible polymer nanocomposite material with an internal conductive network; the electrodes are attached to both ends of the flexible sensing substrate.
[0009] A method for preparing a strain sensor that combines motion monitoring and all-weather rehabilitation therapy functions includes the following steps.
[0010] (1) Preparation of flexible polymer nanocomposite sheet: The flexible polymer material is premixed with conductive nanoparticles and then melt-blended to prepare a flexible polymer nanocomposite material; the above flexible polymer nanocomposite material is prepared into a flexible polymer nanocomposite sheet with an internal conductive network by compression molding or injection molding.
[0011] (2) Preparation of flexible sensing substrate: The flexible polymer nanocomposite sheet prepared above is placed in a solvent to swell for a period of time, and then placed in a mixed solution of oxidant and dopant. The solvent molecules adsorbed on the surface and inside of the sheet undergo an oxidative polymerization reaction with the oxidant, forming a conductive polymer microlayer on the surface of the sheet, and making the interfacial bonding between the sheet surface and the polymer microlayer strong. After the reaction is completed, the sheet is taken out and ultrasonically washed and dried to precipitate the solvent that did not participate in the reaction inside the sheet. During this process, the flexible polymer nanocomposite sheet and the conductive polymer microlayer on its surface undergo volume shrinkage. Since the shrinkage rate of the former is higher than that of the latter, when the former shrinks back to its initial size, the conductive polymer microlayer on the surface spontaneously forms a micro-wrinkled structure, thus obtaining a flexible sensing substrate with a micro-wrinkled functional layer on the surface.
[0012] (3) Fabrication of strain sensor: The electrodes are attached to both ends of the above-mentioned flexible sensing substrate to fabricate a strain sensor that combines motion monitoring and all-weather rehabilitation therapy functions.
[0013] As a preferred embodiment, in step (1), the flexible polymer material is a thermoplastic polyurethane (TPU) elastomer, ethylene-octene copolymer, or silicone rubber; the conductive nanoparticles are one or more of carbon-based conductive nanoparticles, transition metal carbides, conductive metal particles, and flexible conductive polymer materials.
[0014] As a preferred option, in step (1), when preparing flexible polymer nanocomposite sheet by compression molding, the flexible polymer nanocomposite material is placed in the mold cavity with a fixed template, the mold is heated to melt the flexible polymer nanocomposite material, and the melt fills the mold cavity under pressure. After pressure holding, cooling and shaping, a flexible polymer nanocomposite sheet with a thickness of 0.1 to 1 mm is obtained.
[0015] As a preferred option, in step (1), when preparing flexible polymer nanocomposite sheet by injection molding, the flexible polymer nanocomposite material is melted and mixed into a melt using an injection molding machine. The melt is then injected into a mold cavity with a fixed template. Under the action of the filling pressure or the mold compression force, the melt fills the mold cavity. After the melt is held under pressure, cooled and shaped, a flexible polymer nanocomposite sheet with a thickness of 0.1 to 1 mm is obtained.
[0016] As a preferred option, in step (1), when preparing flexible polymer nanocomposite sheets by compression molding or injection molding, the template is fixed in the mold cavity to prepare flexible polymer nanocomposite sheets with smooth surfaces or microstructures; the microstructures on the surface of the sheet are concave pyramids or cylinders, and the characteristic dimensions and center distance of the microstructures are 10 to 500 μm.
[0017] As a preferred embodiment, in step (2), the solvent is a pyrrole solution, the swelling time is 0.5 to 20 min; the oxidant is ferric chloride hexahydrate, and the dopant is hydrochloric acid, wherein the concentration of ferric chloride hexahydrate is 0.005 to 0.8 mol / L, and the concentration of hydrochloric acid is 0.5 to 1.5 mol / L; the oxidative polymerization reaction time is 0.5 to 5 min; after the oxidative polymerization reaction, a polypyrrole (PPy) layer with a micro-wrinkled structure is formed on the surface of the flexible polymer nanocomposite sheet.
[0018] As a preferred option, in step (3), the electrode is made of copper foil with a thickness of 0.02 to 0.2 mm.
[0019] The motion monitoring working principle of the strain sensor prepared in this invention, which combines motion monitoring and all-weather rehabilitation therapy functions, is as follows. Under tensile strain, the micro-folds in the functional layer are gradually stretched open, causing micro-cracks to form at the troughs of the micro-folds, thus increasing the sensor's resistance. As the tensile strain increases, the strong interfacial bonding between the flexible polymer nanocomposite sheet and the functional layer causes the original micro-cracks in the functional layer to continue to expand into longer and wider cracks, while generating new cracks, further increasing the sensor's resistance, thereby achieving the sensor's motion monitoring purpose.
[0020] The rehabilitation therapy working principle of the strain sensor prepared in this invention, which combines motion monitoring and all-weather rehabilitation therapy functions, is as follows. In a well-lit environment, the light-trapping properties of the surface micro-wrinkled structure allow more incident sunlight to be absorbed by the functional layer and converted into photothermal energy, causing the temperature of the functional layer to rise rapidly. This heat is then transferred to the lower-temperature areas of the sensor through a conductive network with high thermal conductivity within the flexible polymer nanocomposite sheet, thus improving the uniformity of the sensor surface temperature distribution. In a poorly lit environment, both the functional layer and the conductive network within the flexible polymer nanocomposite sheet have high conductivity. When direct current is applied, Joule heating is generated on the sensor surface and inside, causing the temperature of the sensor surface and inside to rise rapidly.
[0021] An application of a strain sensor that combines motion monitoring and all-weather rehabilitation therapy functions utilizes the micro-folded structure of the functional layer for strain sensing and the photothermal and / or electrothermal effects of the conductive network within the functional layer and flexible polymer nanocomposite sheet for all-weather rehabilitation therapy.
[0022] The present invention has the following advantages.
[0023] (1) The present invention uses solvent swelling and oxidative polymerization reaction to carry out polymerization reaction from the surface of flexible polymer nanocomposite sheet to the inside, so that the flexible polymer nanocomposite sheet and the micro-wrinkled structure functional layer have strong interfacial bonding and improve the functional durability of the sensor.
[0024] (2) Flexible polymer nanocomposite sheet is prepared by melt mixing and compression molding or injection molding. The method is simple and easy to implement, and can achieve mass production and low cost. It is easy to promote in industry and has broad application prospects.
[0025] (3) Thanks to the inherent photothermal / electrothermal properties of the micro-folded structure functional layer, the high thermal conductivity of the conductive network in the flexible polymer nanocomposite sheet, and the light-trapping properties of the micro-folded structure, the strain sensor prepared exhibits all-weather rehabilitation and physiotherapy performance of photothermal and electrothermal.
[0026] (4) By changing the content of conductive nanoparticles in the flexible polymer nanocomposite material to regulate the structure of the conductive network and by changing the swelling time, oxidant concentration, dopant concentration and oxidative polymerization reaction time to regulate the thickness of the functional layer, the coordination between these two can improve the sensing performance of the strain sensor; by regulating the structure of the conductive network and the thickness of the functional layer, a rapid and uniform thermotherapy effect can be achieved in all weather conditions, which is conducive to broadening the application range of the strain sensor. Attached Figure Description
[0027] Figure 1This is a schematic diagram of the strain sensor prepared according to the present invention, which combines motion monitoring and all-weather rehabilitation therapy functions. In the figure, 1 represents a flexible sensing substrate, 1.1 represents a functional layer with a micro-wrinkled structure, 1.2 represents a flexible polymer nanocomposite sheet with an internal conductive network, and 2 represents an electrode.
[0028] Figure 2 The image shows a scanning electron microscope image of the brittle fracture surface of the flexible sensing substrate of the strain sensor prepared in this invention, which combines motion monitoring and all-weather rehabilitation therapy functions, corresponding to Example 1.
[0029] Figure 3 This is a schematic diagram of the motion monitoring working principle of the strain sensor prepared in this invention, which combines motion monitoring and all-weather rehabilitation therapy functions, corresponding to Example 1.
[0030] Figure 4 The curve showing the change in relative resistance (ΔR / R0) of the strain sensor prepared in this invention, which combines motion monitoring and all-weather rehabilitation therapy functions, as a function of tensile strain, corresponds to Example 1.
[0031] Figure 5 The results of using the strain sensor prepared in this invention, which combines motion monitoring and all-weather rehabilitation therapy functions, for human motion monitoring are shown in Example 1.
[0032] Figure 6a To illustrate the surface temperature change curve of the strain sensor prepared in this invention under vertical illumination by a simulated 1sun light source, the figure also shows the surface temperature change curve of human skin under the same illumination conditions as a comparison, corresponding to Example 1.
[0033] Figure 6b The curves showing the surface temperature of the strain sensor prepared in this invention changing over time under vertical illumination by simulated light sources of different intensities correspond to Example 1.
[0034] Figure 7 The curves showing the surface temperature change over time of the strain sensor prepared according to the present invention when connected to DC power of different voltages correspond to Example 1.
[0035] Figure 8 The curve showing the change in relative resistance (ΔR / R0) of the strain sensor prepared in this invention, which combines motion monitoring and all-weather rehabilitation therapy functions, as a function of tensile strain, corresponds to Example 2.
[0036] Figure 9 This is a scanning electron microscope image of the surface of the flexible sensing substrate of the strain sensor prepared in this invention, corresponding to Example 3. Detailed Implementation
[0037] The present invention will be further described in detail below with reference to the embodiments and accompanying drawings, but the implementation of the present invention is not limited thereto.
[0038] Figure 1 This is a schematic diagram of the strain sensor prepared according to the present invention, which combines motion monitoring and all-weather rehabilitation therapy functions. The sensor consists of a flexible sensing substrate 1 and electrodes 2. The flexible sensing substrate 1 is composed of a functional layer 1.1 with a micro-wrinkled structure and a flexible polymer nanocomposite sheet 1.2 with an internal conductive network. The electrodes 2 are attached to both ends of the flexible sensing substrate.
[0039] Example 1
[0040] This embodiment describes a method for preparing a strain sensor that combines motion monitoring and all-weather rehabilitation therapy functions, comprising the following steps.
[0041] (1) Preparation of flexible polymer nanocomposite sheet: Dried TPU particles and multi-walled carbon nanotube (MWCNT) powder were premixed at a mass ratio of 98:2 and then added to a mixer for melt mixing. The mixing temperature was 190℃, the rotor speed was 100rpm, and the mixing time was 15min. The melt obtained by melt mixing was placed in a mold cavity and placed in a molding press. After being kept at 190℃ and 10MPa for 5min, it was cooled, shaped, and demolded to obtain a flexible TPU-based nanocomposite sheet with a thickness of 0.3mm.
[0042] (2) Preparation of flexible sensing substrate: The flexible TPU-based nanocomposite sheet prepared above is placed in a pyrrole solution to swell, so that the pyrrole enters the interior of the sheet. After 3 minutes, it is taken out and the residual solution on its surface is wiped off with test paper. A mixed solution of ferric chloride hexahydrate and hydrochloric acid was prepared, with the concentration of ferric chloride hexahydrate being 0.2 mol / L and the concentration of hydrochloric acid being 1.0 mol / L. A flexible TPU-based nanocomposite sheet was placed in the mixed solution. Pyrrole molecules adsorbed on and inside the sheet underwent an oxidative polymerization reaction with ferric ions, forming a conductive PPy microlayer on the sheet surface and establishing a strong interfacial bond between the sheet surface and the PPy microlayer. After reacting for 1 minute, the sheet was removed and ultrasonically cleaned three times with deionized water to remove excess solvent. It was then dried in a fume hood for 24 hours to allow unreacted pyrrole to precipitate. During this process, the flexible TPU-based nanocomposite sheet and its surface PPy microlayer underwent volume shrinkage. Since the former had a higher shrinkage rate than the latter, when the former shrank back to its initial size, the surface PPy microlayer spontaneously formed a micro-wrinkled structure, resulting in a flexible sensing substrate with a functional layer of micro-wrinkled structure on its surface.
[0043] (3) Preparation of strain sensor: Copper foil is pasted on both ends of the above flexible sensing substrate to prepare a strain sensor with both motion monitoring and all-weather rehabilitation physiotherapy functions.
[0044] Figure 2 The image shown is a scanning electron microscope (SEM) image of the brittle fracture surface of the flexible sensing substrate of the strain sensor prepared in this embodiment, which combines motion monitoring and all-weather rehabilitation therapy functions. It can be seen that a PPy layer with a micro-wrinkled structure is formed on the surface of the flexible TPU-based nanocomposite sheet.
[0045] Figure 3 This diagram illustrates the motion monitoring working principle of the strain sensor prepared in this embodiment, which combines motion monitoring and all-weather rehabilitation therapy functions. Under tensile strain, the micro-folds in the functional layer are gradually stretched open, causing micro-cracks to form at the troughs of the micro-folds, increasing the sensor's resistance. As the tensile strain increases, the strong interfacial bonding between the flexible TPU-based nanocomposite sheet and the functional layer causes the existing micro-cracks in the functional layer to continue to expand into longer and wider cracks, while also generating new cracks, further increasing the sensor's resistance, thereby achieving the sensor's motion monitoring purpose.
[0046] Figure 4 The curves showing the relative resistance change (ΔR / R0) of the strain sensor prepared for this embodiment, which combines motion monitoring and all-weather rehabilitation therapy functions, are presented as a function of tensile strain. It can be seen that as strain increases, the ΔR / R0 of the strain sensor first increases slowly, and then increases rapidly; within the strain ranges of approximately 0–20%, 20–30%, and 30%–50%, the corresponding strain factors of the sensor are 0.8 (GF1), 3.7 (GF2), and 8.3 (GF3), respectively.
[0047] Figure 5 The results of using the strain sensor prepared for this embodiment, which combines motion monitoring and all-weather rehabilitation therapy functions, for human motion monitoring. Figure 5 In methods a, b, and c, the sensor was attached to the back of the test subject's neck, wrist, and the outer side of their elbow. When the test subject lowered their head, bent their wrist, and bent their arm, the sensor's resistance increased significantly. When the test subject raised their head, straightened their wrist, and straightened their arm, the sensor's resistance quickly returned to its initial value, and the output resistance all exhibited periodicity and good stability. Figure 5 As shown in Figure d, the sensor was attached to the index finger joint of the tester. When the index finger joint was bent at different angles (30°, 45°, and 90°), the ΔR / R0 value increased with the increase of the finger bending angle, indicating that the strain sensor has the ability to sense the bending angle of the finger joint. Figure 5As shown in Figure e, the sensor is attached to the knee joint of the test subject. When the test subject repeatedly performs walking, running and squatting movements, the resistance output by the sensor shows different frequencies or waveforms, and the output resistance shows good stability. The test subject's leg movement status can be judged by the output resistance.
[0048] Figure 6a To illustrate the surface temperature change of the strain sensor prepared in this embodiment under vertical illumination from a simulated 1sun light source, the figure also includes a comparison curve of the surface temperature change of human skin under the same illumination conditions. It can be seen that after 300s of irradiation, the surface temperature of the strain sensor reaches 75.4℃, which is approximately 35℃ higher than that of human skin.
[0049] Figure 6b The graph shows the surface temperature of the strain sensor prepared in this embodiment as a function of time under vertical illumination from simulated light sources of different intensities. It can be seen that when the light intensity increases from 0.5 to 2 sun, after 30 seconds of irradiation, the surface temperature of the strain sensor increases from 31.9℃ to 75.4℃.
[0050] Figure 7 The graph shows the surface temperature of the strain sensor prepared in this embodiment as a function of time when connected to DC voltages of different voltages. It can be seen that when applied voltages of 10, 15, and 20V are applied for 180s, the surface temperature of the strain sensor increases from room temperature (24.2℃) to 30.5, 38.6, and 48.5℃, respectively.
[0051] Example 2
[0052] This embodiment describes a method for preparing a strain sensor that combines motion monitoring and all-weather rehabilitation therapy functions. The steps are the same as those in Embodiment 1, except that in step (1), the dried TPU particles are premixed with MWCNTs powder at a mass ratio of 99:1.
[0053] Figure 8 The curve showing the change in relative resistance (ΔR / R0) of the strain sensor prepared for this embodiment, which combines motion monitoring and all-weather rehabilitation therapy functions, as a function of tensile strain. It can be seen that as strain increases, the ΔR / R0 of the strain sensor first increases slowly, and then increases rapidly; in the strain ranges of approximately 0–30%, 30–40%, and 40%–50%, the corresponding strain factors of the sensor are 0.2 (GF1), 1.9 (GF2), and 4.9 (GF3), respectively.
[0054] The strain sensor prepared in this embodiment was subjected to photothermal and electrothermal performance tests.
[0055] Example 3
[0056] This embodiment describes a method for preparing a strain sensor that combines motion monitoring and all-weather rehabilitation therapy functions. The steps are the same as those in Embodiment 1. The difference lies in step (1), where a metal template with a micro pyramid structure array on the surface, prepared by precision milling, is fixed in the mold cavity, and a flexible TPU-based nanocomposite sheet is molded to obtain a flexible TPU-based nanocomposite sheet with a concave pyramid structure on the surface.
[0057] Figure 9 The image shown is a scanning electron microscope image of the flexible sensing substrate surface of the strain sensor prepared in this embodiment. As can be seen, the surface of the flexible sensing substrate has a regularly arranged array of concave pyramids, each concave pyramid having a base side length of 150 μm and a center-to-center distance of 170 μm between two adjacent concave pyramids. The surface of the concave pyramid array has a micro-wrinkled structure.
[0058] The strain sensor prepared in this embodiment was subjected to strain sensing, photothermal and electrothermal performance tests.
[0059] 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 strain sensor that combines motion monitoring and all-weather rehabilitation therapy functions, characterized in that, The strain sensor consists of a flexible sensing substrate and electrodes; the flexible sensing substrate consists of a functional layer with a micro-wrinkled structure and a thin sheet of flexible polymer nanocomposite material with an internal conductive network; the electrodes are attached to both ends of the flexible sensing substrate.
2. A method for preparing a strain sensor that combines motion monitoring and all-weather rehabilitation therapy functions, characterized in that, Includes the following steps: (1) Preparation of flexible polymer nanocomposite sheet: The flexible polymer material is premixed with conductive nanoparticles and then melt-blended to prepare a flexible polymer nanocomposite material; the above flexible polymer nanocomposite material is prepared into a flexible polymer nanocomposite sheet with an internal conductive network by compression molding or injection molding. (2) Preparation of flexible sensing substrate: The flexible polymer nanocomposite sheet prepared above is placed in a solvent to swell for a period of time, and then placed in a mixed solution of oxidant and dopant. The solvent molecules adsorbed on the surface and inside of the sheet undergo an oxidative polymerization reaction with the oxidant, forming a conductive polymer microlayer on the surface of the sheet, and making the interfacial bonding between the sheet surface and the polymer microlayer strong. After the reaction is completed, the sheet is taken out and ultrasonically washed and dried to precipitate the solvent that did not participate in the reaction. During this process, the flexible polymer nanocomposite sheet and the conductive polymer microlayer on its surface undergo volume shrinkage. Since the shrinkage rate of the former is higher than that of the latter, when the former shrinks back to its initial size, the conductive polymer microlayer on the surface spontaneously forms a micro-wrinkled structure, thus obtaining a flexible sensing substrate with a micro-wrinkled structure functional layer on the surface. (3) Fabrication of strain sensor: The electrodes are attached to both ends of the above-mentioned flexible sensing substrate to fabricate a strain sensor that combines motion monitoring and all-weather rehabilitation therapy functions.
3. The method for preparing the strain sensor with both motion monitoring and all-weather rehabilitation therapy functions according to claim 2, characterized in that, In step (1), the flexible polymer material is a thermoplastic polyurethane elastomer, ethylene-octene copolymer or silicone rubber; the conductive nanoparticles are one or more of carbon-based conductive nanoparticles, transition metal carbides, conductive metal particles and flexible conductive polymer materials.
4. The method for preparing the strain sensor with both motion monitoring and all-weather rehabilitation therapy functions according to claim 2, characterized in that, In step (1), when preparing flexible polymer nanocomposite sheet by compression molding, the flexible polymer nanocomposite material is placed in the mold cavity with a fixed template, the mold is heated to melt the flexible polymer nanocomposite material, and the melt fills the mold cavity under pressure. After pressure holding, cooling and shaping, a flexible polymer nanocomposite sheet with a thickness of 0.1 to 1 mm is obtained.
5. The method for preparing the strain sensor with both motion monitoring and all-weather rehabilitation therapy functions according to claim 2, characterized in that, In step (1), when preparing flexible polymer nanocomposite sheet by injection molding, the flexible polymer nanocomposite material is melted and mixed into a melt using an injection molding machine. The melt is then injected into a mold cavity with a fixed template. Under the action of the filling pressure or the mold compression force, the melt fills the mold cavity. After the melt is held under pressure, cooled and shaped, a flexible polymer nanocomposite sheet with a thickness of 0.1 to 1 mm is obtained.
6. The method for preparing the strain sensor with both motion monitoring and all-weather rehabilitation therapy functions according to claim 2, characterized in that, In step (1), when preparing flexible polymer nanocomposite sheets by compression molding or injection molding, the template is fixed in the mold cavity to prepare flexible polymer nanocomposite sheets with smooth surfaces or microstructures; the microstructures on the surface of the sheet are concave pyramids or cylinders, and the characteristic size and center distance of the microstructures are 10 to 500 μm.
7. The method for preparing the strain sensor with both motion monitoring and all-weather rehabilitation therapy functions according to claim 2, characterized in that, In step (2), the solvent is a pyrrole solution, the swelling time is 0.5 to 20 min; the oxidant is ferric chloride hexahydrate, the dopant is hydrochloric acid, wherein the concentration of ferric chloride hexahydrate is 0.005 to 0.8 mol / L, the concentration of hydrochloric acid is 0.5 to 1.5 mol / L; the oxidative polymerization reaction time is 0.5 to 5 min. After oxidative polymerization, a polypyrrole layer with a micro-wrinkled structure is formed on the surface of a flexible polymer nanocomposite sheet.
8. The method for preparing the strain sensor with both motion monitoring and all-weather rehabilitation therapy functions according to claim 2, characterized in that, In step (3), the electrode is made of copper foil with a thickness of 0.02 to 0.2 mm.
9. The application of the strain sensor with both motion monitoring and all-weather rehabilitation therapy functions as described in claim 1, characterized in that, The working principle of motion monitoring is that under tensile strain, the micro-folds of the functional layer are gradually stretched apart, causing micro-cracks to be generated at the troughs of the micro-folds, which increases the resistance of the sensor. As the tensile strain increases, the strong interfacial bonding between the flexible polymer nanocomposite sheet and the functional layer causes the original micro-cracks in the functional layer to continue to expand into longer and wider cracks, while generating new cracks, which further increases the resistance of the sensor, thereby achieving the motion monitoring purpose of the sensor.
10. The application of the strain sensor with both motion monitoring and all-weather rehabilitation therapy functions as described in claim 1, characterized in that, The working principle of rehabilitation physiotherapy is as follows: In a well-lit environment, the light-trapping properties of the surface micro-wrinkled structure allow more incident sunlight to be absorbed by the functional layer and converted into photothermal energy, causing the temperature of the functional layer to rise rapidly. This heat is then transferred to the cooler areas of the sensor through a conductive network with high thermal conductivity within the flexible polymer nanocomposite sheet, thereby improving the uniformity of the sensor surface temperature distribution. In a poorly lit environment, both the functional layer and the conductive network within the flexible polymer nanocomposite sheet have high conductivity. When direct current is applied, Joule heating is generated on the sensor surface and inside, causing the temperature of the sensor surface and inside to rise rapidly.