A nanofiber-based material with dual-mode thermal management and health detection function, and a preparation method and application thereof

Abstract

The application discloses a kind of nanofiber-based materials with dual-mode thermal management and health detection function and its preparation method and application, belong to nanometer material technical field.The application integrates radiation heating nanofiber, radiation cooling nanofiber, fiber-based strain sensor and temperature sensor into one body.Radiation cooling layer is composed of TPU nanofiber with high mid-infrared emissivity and high reflectivity.Radiation heating layer is composed of CNT / TPU nanofiber with high absorptivity.The strain sensing layer with high sensitivity of wrinkle structure and crack structure is sandwiched between radiation cooling layer and radiation heating layer, which can monitor human respiratory signal in a non-restricted manner.The temperature sensing layer is directly printed on the TPU nanofiber layer by ink direct writing 3D printing technology.Benefiting from the network structure of TPU nanofiber, the material has excellent waterproofness and air permeability, and can be worn comfortably for a long time.

Description

Technical Field

[0001] This invention belongs to the field of nanomaterials technology, specifically relating to a nanofiber-based material with dual-mode thermal management and health monitoring functions, its preparation method, and its application. Background Technology

[0002] The information disclosed in this background section is intended only to enhance understanding of the overall background of the invention and is not necessarily to be construed as an admission or in any way implying that such information constitutes prior art known to those skilled in the art.

[0003] Prolonged exposure to hot or cold environments can cause discomfort, heat stress, and cold stress, leading to increases or decreases in skin and body temperature. According to "thermal comfort" standards, excessively high (>38.3℃) or low (35.0℃) core body temperatures can be life-threatening. Therefore, extreme weather significantly increases the probability of injury, illness, and sudden death. However, a large number of people (such as street cleaners and outdoor electricians) inevitably work in harsh environments, such as cold winters and hot summers, requiring them to adapt to varying temperatures throughout the year. Currently, space cooling or heating methods primarily rely on air conditioning systems or building heating, which is uneconomical for open outdoor environments and wastes resources. Therefore, there is an urgent need to develop smart wearable products capable of controlling body temperature through energy-free or energy-saving strategies.

[0004] Wearable materials, acting as a direct barrier between the human body and the external environment, can achieve thermal comfort by modulating the micro-spaces and material radiation close to the body. This contributes to providing more precise, portable thermal management with low energy consumption. Currently, various personal thermal management materials are used to improve human thermal comfort, such as rubber elastomers, silica, polydimethylsiloxane, and polyethylene. However, most personal thermal management materials are solid structures, which reduces cooling (e.g., hindering heat dissipation) or heating effects and can cause skin discomfort or severe inflammation after prolonged wear. Many passive radiative cooling materials only provide cooling in warm weather and cannot match the temperature fluctuations of hot and cold seasons. Therefore, manufacturing a single breathable wearable device that can switch between cooling and heating to adapt to various conditions is a significant challenge.

[0005] Furthermore, many researchers have found that the frequency and intensity of respiratory signals are affected by temperature and can reflect a person's health status. Flexible wearable devices that provide temperatures suitable for human life and health and monitor human respiratory signals are of great significance for reducing the harm to humans from harsh environments (such as high and low temperatures), reducing mortality rates, and protecting Earth's resources. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the purpose of this invention is to provide a nanofiber-based material with dual-mode thermal management and health monitoring functions, its preparation method, and its application. The nanofiber-based material with dual-mode thermal management and health monitoring functions provided by this invention can be used to make clothing, which not only has thermal management functions but also health monitoring functions, effectively avoiding the harm to the human body from severe weather in two ways.

[0007] To achieve the above objectives, the technical solution of the present invention is as follows:

[0008] A first aspect of the present invention provides a nanofiber-based material with dual-mode thermal management and health monitoring functions, comprising a radiative cooling layer, a strain sensing layer, and a radiative heating layer, wherein:

[0009] The radiation cooling layer is a thermoplastic polyurethane nanofiber membrane;

[0010] The radiant heating layer is a carbon nanotube / thermoplastic polyurethane nanofiber membrane.

[0011] The strain sensing layer has a micro-fold and micro-crack structure and is used to monitor human respiratory signals. It is disposed between the radiative cooling layer and the radiative heating layer.

[0012] In some embodiments of the present invention, the nanofiber-based material further includes a temperature sensor for monitoring human body temperature, which is disposed above the radiative cooling layer.

[0013] Preferably, the temperature sensor is obtained by printing slurry onto a predetermined position of the radiation cooling layer using ink direct writing 3D printing technology.

[0014] In some embodiments of the present invention, the dual-mode thermal management includes two modes: passive heating and passive cooling. The radiative cooling layer is used for passive cooling, and the radiative heating layer is used for passive heating.

[0015] The health monitoring includes respiratory monitoring and body temperature monitoring.

[0016] This invention provides a nanofiber-based material with dual-mode thermal management and health monitoring functions. The strategy of this invention is to integrate radiative heating nanofibers, radiative cooling nanofibers, a fiber-based strain sensor, and a temperature sensor into a single unit. The cooling surface (i.e., the radiative cooling layer) is one surface of the nanofiber-based material, composed of electrospun thermoplastic polyurethane (TPU) nanofibers with high infrared (IR) emissivity and high reflectivity. The heating surface (i.e., the radiative heating layer) is the other surface of the nanofiber-based material, composed of electrospun carbon nanotubes (CNTs) / TPU nanofibers with high visible light absorption. A highly sensitive strain sensing layer with a wrinkled and cracked structure is sandwiched between the radiative cooling TPU nanofiber layer and the radiative heating CNT / TPU nanofiber layer, enabling unrestricted monitoring of human respiratory signals. The temperature sensing layer is achieved by directly printing the slurry onto the TPU nanofiber layer using ink-direct writing 3D printing technology. Furthermore, thanks to the TPU nanofiber network structure (with numerous internal open micropores and microchannels), this nanofiber-based material exhibits excellent waterproof and breathable properties (41.2 mm s). -1 This invention provides a unique method for realizing a multifunctional wearable electronic device for human thermal management and monitoring of physiological signals such as respiration and temperature. It can be worn comfortably for extended periods.

[0017] The nanofiber-based material provided by this invention possesses functions such as breathability, waterproofing, passive radiative cooling, passive radiative heating, strain respiratory monitoring, and human body temperature monitoring. It allows for selection of clothing wearing methods based on ambient temperature, effectively preventing harm to the human body from harsh environments. In high-temperature environments, the radiative cooling layer can be worn on the outside for passive radiative cooling, effectively lowering body temperature and preventing heatstroke. In low-temperature environments, the radiative heating layer can be worn on the outside for passive radiative heating, effectively maintaining body temperature and reducing injury and mortality rates in extreme temperatures.

[0018] A second aspect of the present invention provides a method for preparing a nanofiber-based material with dual-mode thermal management and health monitoring functions, comprising the following steps:

[0019] Preparation of the radiation cooling layer: Thermoplastic polyurethane is dissolved in an organic solvent to obtain an electrospinning solution. The spinning solution is electrospinned and dried to obtain a thermoplastic polyurethane fiber membrane.

[0020] Preparation of the radiant heating layer: Carbon nanotube solution is sprayed onto the surface of the thermoplastic polyurethane fiber membrane, and dried after spraying to obtain a carbon nanotube / thermoplastic polyurethane nanofiber membrane.

[0021] Preparation of strain sensing layer: Poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonic acid), carbon nanotubes and silver nanowires are mixed to obtain a mixed solution; the mixed solution is sprayed onto both sides of a pre-stretched thermoplastic polyurethane fiber membrane, dried after spraying, and the pre-stretched fixture is released after drying to obtain the strain sensing layer.

[0022] Composite: The radiation cooling layer, hot melt adhesive film, strain sensing layer, hot melt adhesive film, and radiation heating layer are arranged in a top-to-bottom order, and heated to bond the layers into a whole, thus obtaining a nanofiber-based material with dual-mode thermal management and health monitoring functions.

[0023] The pre-stretching and spraying process gives the strain sensing layer a lot of micro-folds and micro-cracks, which can produce a larger resistance change under the same stretching conditions, thus effectively increasing the sensitivity of the strain sensing layer.

[0024] In some embodiments of the present invention, the organic solvent is selected from at least one of dimethyl sulfoxide, D,D-dimethylformamide and tetrahydrofuran.

[0025] Preferably, the organic solvent is a mixed solution obtained by mixing dimethyl sulfoxide, D,D-dimethylformamide and tetrahydrofuran in a mass ratio of 1:4-5:4-5.

[0026] In some embodiments of the present invention, the amount of the thermoplastic polyurethane is 15-17 wt% of the organic solvent.

[0027] In some embodiments of the present invention, the concentration of the carbon nanotube solution is 5-8 mg / mL.

[0028] In some embodiments of the present invention, the solvent of the carbon nanotube solution is deionized water.

[0029] In some embodiments of the present invention, the mass ratio of poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonic acid), carbon nanotubes and silver nanowires is 1-2:1-2:1-2.

[0030] In some embodiments of the present invention, the pre-stretched thermoplastic polyurethane fiber membrane is pre-stretched to 0%-80% using a clamp.

[0031] Thanks to the doping method, which mixes poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonic acid) (PEDOT:PSS), CNTs and silver nanowires (Ag NW), and the cracked microstructure obtained by pre-stretching, the strain sensing layer exhibits a high strain coefficient (GF, ~368.58), fast response (50 ms) and good stability (over 10,000 cycles).

[0032] In some embodiments of the present invention, the preparation method further includes the preparation of a temperature sensor, which includes the following:

[0033] Two-dimensional graphene sheets, poly(3,4-ethylenedioxythiophene)-poly(styrene sulfonic acid), polyvinyl alcohol and deionized water are mixed and heated and stirred until all components are completely dissolved to obtain a slurry; the slurry is then printed onto the thermoplastic polyurethane fiber membrane of the nanofiber-based material according to the desired shape using ink direct writing 3D printing technology.

[0034] Microsheet and Pore Structure of Temperature Sensor: The two-dimensional sheet structure of graphene and the microporous structure of polyvinyl alcohol enable the temperature sensor to undergo greater deformation and a greater change in resistance at the same temperature, resulting in higher sensitivity.

[0035] In some embodiments of the present invention, the mass ratio of two-dimensional graphene sheet, poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonic acid), polyvinyl alcohol and deionized water is 1-5:5:1:4.

[0036] Thanks to microstructured graphene (G) nanosheets and PEDOT:PSS with a Seebeck coefficient, the temperature sensor displayed -0.013℃. -1 (25-55℃) and -0.003℃ -1 High temperature sensitivity (55-100℃).

[0037] A third aspect of the present invention provides the application of the above-described nanofiber-based material or the nanofiber-based material prepared by the above-described preparation method in the field of wearable devices.

[0038] Preferably, the nanofiber-based material is used to prepare clothing;

[0039] More preferably, the garment has dual-mode thermal management and health monitoring functions; the dual-mode thermal management includes two modes: passive heating and passive cooling, with the radiant cooling layer used for passive cooling and the radiant heating layer used for passive heating; the health monitoring includes respiratory monitoring and body temperature monitoring.

[0040] The beneficial effects of this invention are as follows:

[0041] This invention provides a nanofiber-based material with dual-mode thermal management and health monitoring functions, comprising a radiative cooling layer, a strain sensing layer, and a radiative heating layer, wherein: the radiative cooling layer is a thermoplastic polyurethane nanofiber membrane; the radiative heating layer is a carbon nanotube / thermoplastic polyurethane nanofiber membrane; the strain sensing layer has a micro-wrinkled and micro-cracked structure for monitoring human respiratory signals, and is disposed between the radiative cooling layer and the radiative heating layer. The strategy of this invention is to integrate radiative heating nanofibers, radiative cooling nanofibers, a fiber-based strain sensor, and a temperature sensor into a single unit. The cooling surface (i.e., the radiative cooling layer) is one surface of the nanofiber-based material, composed of electrospun thermoplastic polyurethane (TPU) nanofibers with high infrared (IR) emissivity and high reflectivity. The heating surface (i.e., the radiative heating layer) is the other surface of the nanofiber-based material, composed of electrospun carbon nanotube (CNT) / TPU nanofibers with high absorptivity. A strain-sensing layer with a highly sensitive wrinkled and cracked structure is sandwiched between a radiation-cooled TPU nanofiber layer and a radiation-heated CNT / TPU nanofiber layer, enabling unrestricted monitoring of human respiratory signals. Thanks to its raw material composition and preparation method, the strain-sensing layer exhibits a high strain coefficient (GF, ~368.58), fast response (50 ms), and good stability (over 10,000 cycles). The temperature-sensing layer is created by directly printing slurry onto the TPU nanofiber layer using ink-to-paper 3D printing technology. Benefiting from microstructured graphene (G) nanosheets and PEDOT:PSS with a Seebeck coefficient, the temperature sensor displays -0.013℃. -1 (25–55℃) and -0.003℃ -1 High-temperature sensitivity (55–100℃). Furthermore, thanks to the TPU nanofiber network structure (with numerous internal open micropores and microchannels), this nanofiber-based material exhibits excellent waterproofness and breathability (41.2 mm² / s²). -1 This invention provides a unique method for realizing a multifunctional wearable electronic device for human thermal management and monitoring of physiological signals such as respiration and temperature. It can be worn comfortably for extended periods.

[0042] The nanofiber-based material provided by this invention possesses functions such as breathability, waterproofing, passive radiative cooling, passive radiative heating, strain respiratory monitoring, and human body temperature monitoring. It allows for selection of clothing wearing methods based on ambient temperature, effectively preventing harm to the human body from harsh environments. In high-temperature environments, the radiative cooling layer can be worn on the outside for passive radiative cooling, effectively lowering body temperature and preventing heatstroke. In low-temperature environments, the radiative heating layer can be worn on the outside for passive radiative heating, effectively maintaining body temperature and reducing injury and mortality rates in extreme temperatures. Attached Figure Description

[0043] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0044] Figure 1 This is a schematic diagram of the structure of the nanofiber-based material with dual-mode thermal management and health monitoring functions of the present invention. From top to bottom, it consists of 1-radiative cooling layer, 2-strain sensing layer and 3-radiative heating layer.

[0045] Figure 2 This is a schematic diagram of the fabrication process of the strain sensing layer and the CNT / TPU nanofiber membrane.

[0046] Figure 3 Cutting process for nanofiber-based materials with dual-mode thermal management and health monitoring functions;

[0047] Figure 4 Morphological characterization of nanofiber-based materials with dual-mode thermal management and health monitoring functions is shown below. A is a schematic diagram of the TPU nanofiber structure; B is an electron microscope (EM) image of the TPU nanofibers; C is an EEM image of the CNT / TPU nanofibers; D is a schematic diagram of the strain sensing layer structure; E shows EEM images and elemental analysis diagrams of the strain sensing layer at different scales; F is a schematic diagram of the cross-section of the multifunctional nanofiber-based material; G is an EEM image and elemental analysis diagram of the cross-section of the multifunctional nanofiber-based material; H is a schematic diagram of the temperature sensor structure; and I is an EEM image of the temperature sensor.

[0048] Figure 5 The performance of nanofiber-based materials with dual-mode thermal management and health monitoring functions is characterized, where A represents air permeability, B represents moisture permeability, and C and D represent hydrophobicity.

[0049] Figure 6 The following are the working mechanism and performance tests of the strain sensing layer: A is a diagram of the working mechanism of the strain sensing layer; B is the stress-strain curve of the strain sensing layer, which can withstand a maximum strain of 1.5 MPa and 700%; C is the sensitivity curve of the strain sensing layer, with a sensitivity of 14.69 in the first stage and 368.58 in the second stage; D is the stability test of the strain sensing layer after 10,000 cycles, showing good stability; E is the response time test of the strain sensing layer, with the fastest response time being 50 ms.

[0050] Figure 7 This document presents the sensing mechanism and performance testing of a temperature sensor. A represents the working mechanism of the temperature sensor; B represents the sensitivity curves of temperature sensors with different graphene contents (maximum sensitivity: -0.013℃ in the first stage). -1 (25-50℃), the second stage is -0.0012℃.-1 (50-100℃); C is the response time of the temperature sensor, which is 8s; D is the stability cycle test of the temperature sensor at 30-50℃; E is the step test of the temperature sensor at 25-55℃.

[0051] Figure 8 The cooling function of nanofiber-based materials was tested. A represents the solar reflectance and thermal emissivity of TPU nanofibers; B represents the solar cooling performance of various materials measured at continuous temperature for 4.5 hours (July 20, 2023, Tianjin, China).

[0052] Figure 9 The heating function of nanofiber-based materials was tested. A shows infrared images of the solar heating side of different CNT / TPU nanofibers; B shows the solar heating performance of various materials measured by continuous temperature compression for 4.5 hours.

[0053] Figure 10 For application testing, A represents respiratory signal detection in the intelligent nanofiber cooling mode under high temperature conditions; B represents respiratory signal detection in the heating nanofiber heating mode under low temperature conditions. Detailed Implementation

[0054] To enable those skilled in the art to better understand the technical solution of the present invention, the technical solution of the present invention will be described in detail below with reference to specific embodiments.

[0055] Unless otherwise specified, the raw materials used in the following examples are all commercially available products that can be purchased.

[0056] Example 1

[0057] A method for preparing nanofiber-based materials with dual-mode thermal management and health monitoring functions includes the following steps:

[0058] 1) Fabrication of the radiation cooling layer:

[0059] DMSO, DMF, and THF were added to a beaker in a weight ratio of 1:4:4 and mixed to obtain a mixed solution. Then, TPU particles were added to the mixed solution at a ratio of 15 wt.%, and the beaker was placed in a water bath with a magnetic stirrer at 60°C and stirred for 2 hours until all TPU particles were completely dissolved. The solution was drawn into a 5 mL syringe equipped with a 19 g needle and installed on an electrospinning device. The parameters were set to 15 kV voltage and 0.1 mL / min speed. After spinning for 1-2 hours, a TPU fiber membrane was obtained.

[0060] 2) Preparation of the radiant heating layer:

[0061] DMSO, DMF, and THF were added to a beaker in a weight ratio of 1:4:4 and mixed to obtain a mixed solution. Then, TPU particles were added to the mixed solution at a ratio of 15 wt.%, and the beaker was placed in a water bath with a magnetic stirrer at 60°C and stirred for 2 hours until all TPU particles were completely dissolved. The solution was drawn into a 5 mL syringe equipped with a 19 g needle and installed on an electrospinning device. The parameters were set to 15 kV voltage and 0.1 mL / min speed. After spinning for 1-2 hours, a TPU fiber membrane was obtained.

[0062] A 5 mg / mL CNT deionized water solution was uniformly sprayed onto TPU nanofibers using a spray gun for 1 min to obtain a TPU nanofiber film containing CNTs.

[0063] CNT / TPU nanofiber membranes were obtained by drying TPU nanofiber films containing CNTs in an oven at 60°C for 5 min.

[0064] 3) Fabrication of the strain sensing layer:

[0065] DMSO, DMF, and THF were added to a beaker in a weight ratio of 1:4:4 and mixed to obtain a mixed solution. Then, TPU particles were added to the mixed solution at a ratio of 15 wt.%, and the beaker was placed in a 60°C magnetic stirrer water bath and stirred for 2 hours until all TPU particles were completely dissolved. The solution was drawn into a 5 mL syringe equipped with a 19 g needle and mounted on an electrospinning apparatus. The parameters were set to 15 kV voltage and 0.1 mL / min speed. After spinning for 1-2 hours, a TPU nanofiber film was obtained. The electrospun TPU nanofiber film was pre-stretched by 0%-80% using a fixture.

[0066] Poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonic acid) (PEDOT:PSS), CNTs and silver nanowires (AgNW) were mixed in a weight ratio of 1:1:12 and then stirred for 2 min to obtain a mixed solution.

[0067] The above mixed solution was uniformly sprayed onto both sides of the pre-stretched TPU nanofiber film using a spray gun, with a spraying time of 1 minute on each side.

[0068] The TPU nanofiber film coated with the mixed solution was placed in an oven at 60°C and dried for 5 minutes. After drying, the pre-stretching fixture was released to obtain a strain sensing layer with micro-wrinkles and micro-cracks.

[0069] 4) Preparation of nanofiber-based materials with dual-mode thermal management and health monitoring:

[0070] A) Arrange the TPU fiber membrane (radiative cooling layer), TPU fiber hot melt membrane, strain sensing layer, TPU fiber hot melt membrane, and CNT / TPU nanofiber membrane (radiative heating layer) in the order from top to bottom, and then use a heating stage to bond the above layers into a whole to obtain a nanofiber-based material with dual-mode thermal management and health monitoring.

[0071] like Figure 3 As shown, the nanofiber-based material with dual-mode thermal management and health monitoring obtained above can be cut according to the wearer's size to obtain nanofiber-based clothing with dual-mode thermal management and health monitoring.

[0072] 5) Fabrication of the temperature sensor:

[0073] Two-dimensional graphene sheets, PEDOT:PSS, polyvinyl alcohol particles, and deionized water were added to a beaker in a weight ratio of 1:5:1:4. The beaker was then placed in a water bath with a magnetic stirrer at 90°C and stirred for 1 hour until all polyvinyl alcohol particles were completely dissolved, yielding a slurry. The slurry was then placed into a syringe containing a 19 g needle, mounted on a 3D printer, and printed into the desired shape onto the TPU surface of nanofiber-based materials or nanofiber-based clothing.

[0074] Performance testing:

[0075] (1) Morphological detection

[0076] Electron microscopy was used to observe the structure of each layer of nanofiber-based materials or nanofiber-based clothing. The results are as follows: Figure 4 As shown. Figure 4 A is a schematic diagram of the TPU nanofiber structure; Figure 4 B shows electron micrographs of TPU nanofibers at different scales, clearly revealing the interlaced arrangement of the TPU nanofibers. Figure 4 C is an electron micrograph of CNT / TPU nanofibers, which clearly shows CNTs loaded on TPU nanofibers. Figure 4 D is a schematic diagram of the strain sensing layer structure, which clearly shows that it has a folded structure. Figure 4 E shows electron micrographs and elemental analysis diagrams of the strain sensing layer at different scales; wrinkles and cracks can be clearly observed in the strain sensing layer, which is loaded with CNTs, PEDOT:PSS and silver nanowires. At the same time, the carbon, oxygen and silver elements are distributed very uniformly in the strain sensor. Figure 4 F is a schematic diagram of the cross-section of the multifunctional nanofiber-based material. Figure 4 G shows electron micrographs and elemental analysis diagrams of the cross-section of the multifunctional nanofiber-based material at different scales. The two images clearly show that it has a three-layer structure with a wrinkled middle structure and very uniform distribution of carbon, oxygen and silver elements. Figure 4H is a schematic diagram of the temperature sensor. Figure 4 Image I is an electron microscope image of the temperature sensor. The two images clearly show that graphene has a sheet-like structure.

[0077] (2) Tests on air permeability, moisture permeability and hydrophobicity

[0078] Air permeability and moisture permeability were tested using an air permeability and moisture permeability tester.

[0079] Test results as follows Figure 5 As shown, Figure 5 A is a comparison chart of breathability. Figure 5 B is a comparison chart of moisture permeability. Figure 5 C and Figure 5 D represents the hydrophobic properties. Thanks to the porous nanofibers obtained through electrospinning, the multifunctional nanofiber-based material has better breathability than nylon, moisture permeability comparable to nonwoven fabrics, and excellent hydrophobicity. The contact angle with artificial sweat and water droplets is greater than 120° (a contact angle greater than 90° is considered hydrophobic), ensuring comfortable wear for extended periods and effectively preventing sweat erosion, thus significantly increasing the lifespan of the sensing layer.

[0080] (3) Working principle and performance testing of strain sensing layer

[0081] A digital source meter is connected to both ends of the strain sensing layer to obtain the corresponding resistance value when the layer is stretched.

[0082] The sensitivity and strain range of the strain sensor were tested under different pre-tension conditions. The test results are shown in Table 1 and... Figure 6 As shown.

[0083] Table 1

[0084]

[0085] like Figure 6 As shown, Figure 6 A is a diagram illustrating the working mechanism of the strain sensing layer. During stretching, the conductive path decreases and the resistance increases. Figure 6 B is the stress-strain curve of the strain sensor layer (which can withstand a maximum of 1.5 MPa and 700% strain). Figure 6 C represents the sensitivity curve of the strain sensing layer. The sensitivity in the first stage is 14.69, and the sensitivity in the second stage is 368.58. Figure 6 D represents the stability test of the strain sensing layer after 10,000 cycles, and it still maintains good stability after 10,000 cycles. Figure 6 E represents the response time of the strain sensing layer, with the fastest being 50ms.

[0086] (4) Sensing mechanism and performance testing of temperature sensor

[0087] Connect a digital source meter to both ends of the temperature sensor, and then use a heating platform to raise the temperature of the temperature sensor to obtain the corresponding resistance value.

[0088] Test results as follows Figure 7 As shown, Figure 7 A describes the working mechanism of the temperature sensor: as the temperature rises, the number of water molecules decreases, the spacing between PEDOT:PSS molecules decreases, and the resistance decreases. Figure 7 B represents the sensitivity curves of temperature sensors with different graphene contents, with the highest sensitivity being -0.013℃ in the first stage. -1 (25-50℃), the second stage is -0.0012℃. -1 (50-100℃). Figure 7 C represents the response time of the temperature sensor, which is 8 seconds. Figure 7 D represents the stability of the temperature sensor during cyclic testing at 30-50℃, and it is very stable. Figure 7 The E temperature sensor was tested in a stepped manner from 25 to 55°C.

[0089] (5) Detection of the radiation cooling function of nanofiber-based materials

[0090] Test results as follows Figure 8 As shown, Figure 8 A represents the solar reflectance and thermal emissivity of TPU nanofibers; Figure 8 B represents a 4.5-hour continuous temperature measurement of the solar cooling performance of various materials (July 20, 2023, Tianjin, China). TPU nanofibers showed better cooling performance compared to cotton cloth, achieving a temperature reduction of over 5°C.

[0091] (6) Testing of the radiant heating function of nanofiber-based materials

[0092] Test results as follows Figure 9 As shown, Figure 9 A shows infrared images of the solar-heated side of different CNT / TPU nanofibers. Figure 9 B represents a 4.5-hour continuous temperature compression measurement of the solar heating performance of various materials.

[0093] The tunability of the optical and solar heating properties of a radiative heating layer was systematically studied by spraying carbon nanotubes (CNTs) of different weights. Layers with different CNT amounts (0.05 mL / cm²) were prepared. 2 0.1 mL / cm 2 and 0.25 mL / cm 2 The heating layer of CNT / TPU nanofibers was applied to solar thermal conversion and heating. During a continuous 4.5-hour measurement period, the surface temperature of the simulated skin covered by CNT / TPU nanofibers in heating mode was approximately 9°C higher than that of black cotton.

[0094] (6) Detection of health detection performance of nanofiber-based materials

[0095] Test results as follows Figure 10 As shown, Figure 10 A represents the detection of respiratory signals under intelligent nanofiber cooling mode in a high-temperature environment. Figure 10 B represents the detection of respiratory signals under the heating mode of nanofiber heating in a low-temperature environment.

[0096] For the passive cooling application, volunteers first wore clothing made of nanofiber-based materials in a hot environment, with the TPU side facing outwards towards sunlight. In the first two minutes, the temperature indicated by sensors on the clothing increased from 30.60°C to 40.12°C, and the respiratory signal frequency monitored by strain sensors in the clothing was approximately 25 breaths / min. Under the clothing's cooling mode, the body temperature decreased from 40.12°C to 36.20°C, and the respiratory rate decreased from 25 breaths / min to 21 breaths / min, with a 50% increase in respiratory intensity within 6 minutes. However, after the volunteers changed their clothing to cotton, the temperature rose to 40.11°C, the respiratory rate increased to 24 breaths / min, and the respiratory intensity decreased again by 50%, demonstrating the effectiveness of the cooling mode and the reliability of the fabricated sensors.

[0097] For the heating application, volunteers were first placed in a cold environment (~16°C, controlled by air conditioning) wearing clothing made of nanofiber-based materials, with the CNT / TPU side facing outwards towards sunlight (emitted by an AHD3000W solar simulator). The temperature indicated by the clothing's temperature sensor increased from 30.00°C to 34.15°C within the first two minutes, and the respiratory rate monitored by the clothing's strain sensor was approximately 16 breaths / min. Under the clothing's heating mode, the body temperature rose from 34.15°C to 36.22°C, the respiratory rate increased from 16 breaths / min to 21 breaths / min, and the respiratory intensity decreased by 20% within 6 minutes. However, when the volunteers changed their clothing to cotton, the temperature dropped to 34.19°C, the respiratory rate decreased to 17 breaths / min, and the respiratory intensity increased again by 20%, demonstrating the effectiveness of the heating mode and the reliability of the fabricated sensors. Therefore, people can determine the wearing side of the fabricated clothing through skin perception, temperature sensing on the clothing, or strain sensing (i.e., respiratory rate and respiratory intensity). In this way, people can reduce injury and mortality in extreme temperatures with the help of multifunctional nanofiber fabrics.

[0098] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A nanofiber-based material with dual-mode thermal management and health detection function, comprising a radiative cooling layer, a strain sensing layer and a radiative heating layer, wherein: the radiative cooling layer is a thermoplastic polyurethane nanofiber membrane; the radiative heating layer is a carbon nanotube / thermoplastic polyurethane nanofiber membrane; the strain sensing layer has a micro-crease and micro-crack structure for monitoring human respiratory signals, and is arranged between the radiative cooling layer and the radiative heating layer; the strain sensing layer is prepared by mixing poly (3, 4-ethylenedioxythiophene) -poly (styrene sulfonic acid), carbon nanotubes and silver nanowires to obtain a mixed solution, spraying the mixed solution on both sides of a pre-stretched thermoplastic polyurethane nanofiber membrane, drying after spraying, and releasing the pre-stretching clamp after drying to obtain the strain sensing layer. The nanofiber-based material further comprises a temperature sensor for monitoring human body temperature, which is arranged above the radiative cooling layer. The temperature sensor is obtained by printing slurry on a set position of the radiative cooling layer through 3D printing direct writing technology. The dual-mode thermal management comprises two modes of passive heating and passive cooling, the radiative cooling layer is used for passive cooling, and the radiative heating layer is used for passive heating. The health detection comprises respiratory monitoring and body temperature monitoring.

2. The nanofiber-based material of claim 1, wherein, 5.A method for preparing a nanofiber-based material with dual-mode thermal management and health detection function, comprising the following steps:

3. The nanofiber-based material of claim 2, wherein, Preparation of the radiative cooling layer: dissolving thermoplastic polyurethane in an organic solvent to obtain an electrospinning solution, electrospinning and drying the spinning solution to obtain a thermoplastic polyurethane nanofiber membrane; 4. The nanofiber-based material of claim 1 or 2, wherein, Preparation of the radiative heating layer: spraying a carbon nanotube solution on the surface of the thermoplastic polyurethane nanofiber membrane, drying after spraying to obtain a carbon nanotube / thermoplastic polyurethane nanofiber membrane; Preparation of the strain sensing layer: mixing poly (3, 4-ethylenedioxythiophene) -poly (styrene sulfonic acid), carbon nanotubes and silver nanowires to obtain a mixed solution, spraying the mixed solution on both sides of a pre-stretched thermoplastic polyurethane nanofiber membrane, drying after spraying, and releasing the pre-stretching clamp after drying to obtain the strain sensing layer; Compounding: arranging the radiative cooling layer, a hot melt adhesive film, the strain sensing layer, a hot melt adhesive film and the radiative heating layer in order from top to bottom, heating to bond the layers into a whole to obtain the nanofiber-based material with dual-mode thermal management and health detection function. The organic solvent is selected from at least one of dimethyl sulfoxide, D, D-dimethylformamide and tetrahydrofuran. The organic solvent is a mixed solution obtained by mixing dimethyl sulfoxide, D, D-dimethylformamide and tetrahydrofuran in a mass ratio of 1:4-5:4-5. The amount of the thermoplastic polyurethane is 15-17 wt% of the organic solvent. The concentration of the carbon nanotube solution is 5-8 mg / mL.

6. The production method according to claim 5, wherein The solvent of the carbon nanotube solution is deionized water.

7. The production method according to claim 6, wherein The mass ratio of poly (3, 4-ethylenedioxythiophene) -poly (styrene sulfonic acid), carbon nanotubes and silver nanowires is 1-2:1-2:1-2.

8. The production method according to claim 5, wherein ​ 9. The production method according to claim 5, wherein ​ ​ 10. The production method according to claim 5, wherein ​ Or, the pre-stretched thermoplastic polyurethane nanofiber membrane is pre-stretched to 0-80% using a clamp.

11. The production method according to claim 5, wherein The preparation method further comprises preparation of a temperature sensor, which comprises the following contents: The two-dimensional graphene sheets, poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonic acid), polyvinyl alcohol and deionized water are mixed and heated and stirred until each component is completely dissolved to obtain a slurry; the slurry is printed onto the surface of the thermoplastic polyurethane nanofiber membrane of the nanofiber-based material according to the required shape by using an ink direct writing 3D printing technology.

12. The production method according to claim 11, wherein The mass ratio of the two-dimensional graphene sheets, poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonic acid), polyvinyl alcohol and deionized water is 1-5:5:1:

4.

13. The nanofiber-based material of any one of claims 1-4 or prepared by the preparation method of any one of claims 5-12 is applied in the field of wearable devices.

14. Use according to claim 13, wherein the compound is ###00010### or a pharmaceutically acceptable salt thereof. The nanofiber-based material is used to prepare clothes.

15. The use according to claim 14, wherein the compound is ###00009### 14 The clothes have a dual-mode thermal management and health monitoring function; the dual-mode thermal management includes two modes of passive heating and passive cooling, the radiation cooling layer is used for passive cooling, and the radiation heating layer is used for passive heating; the health monitoring includes breath monitoring and body temperature monitoring. The clothes have a dual-mode thermal management and health monitoring function; the dual-mode thermal management includes two modes of passive heating and passive cooling, the radiation cooling layer is used for passive cooling, and the radiation heating layer is used for passive heating; the health monitoring includes breath monitoring and body temperature monitoring.

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