A method for the preparation of a double-layer composite fabric for sweat self-pumping visualization

Abstract

The application discloses a preparation method of a double-layer composite fabric for sweat self-pumping visualization, and the method comprises the following steps: preparing hydrophilic sheath-core structure composite yarn and hydrophobic sheath-core structure composite yarn respectively through conjugate electrospinning and hydrothermal treatment methods; then taking the hydrophilic composite yarn and the hydrophobic composite yarn as weft yarn, taking ordinary polyester yarn as warp yarn, and weaving the hydrophilic layer and the hydrophobic layer of the composite fabric according to a double-layer fabric organization, so that an asymmetric wetting state is presented on both sides of the fabric; taking a metal wire as a core wire electrode to prepare a yarn-shaped power generation device with a core-sheath structure, and the yarn-shaped power generation device is embedded with the hydrophilic layer of the double-layer fabric, the induced power generation performance of sweat enriched in the hydrophilic layer is detected, and the performance of self-pumping sweat of the double-layer fabric is visualized.

Description

Technical Field

[0001] This invention belongs to the field of functional fabric preparation, and particularly relates to a method for preparing a double-layer composite fabric for visualizing sweat self-pumping. Background Technology

[0002] With the occurrence of extreme heat weather, the incidence of severe heatstroke is very high. The research and development of textiles that can effectively conduct directional sweat transmission to improve the human body's thermal and moisture comfort and utilize sweat for electrical signal conversion has become increasingly urgent.

[0003] Traditional functional textiles made from natural and chemical fibers can accelerate moisture transfer through fiber modification, fabric design, and finishing processes; however, their diameter scale remains at the micrometer level. Considering the unique scale and interface effects of electrospun micro / nano fibers, and their ease of processing and shaping, rationally combining and designing the structure of electrospun micro / nano fibers with traditional fabrics not only provides new research ideas for functional applications in moisture transfer but also opens up more research directions for multifunctional textiles.

[0004] Compared to traditional power generation technologies, hydroelectric power generation is green and environmentally friendly, requiring no large-scale equipment investment to generate electricity, and making full use of water resources to achieve deep exploitation of hydropower. Sweat is also a type of water resource. Fibers and yarns are integrated into clothing through textile processes. By converting the directional transport of sweat into electrical signals through flowing potential, it can monitor the thermal and moisture comfort of fabrics, providing technical data for smart response textiles and emerging energy harvesting methods. Summary of the Invention

[0005] In view of this, the purpose of the present invention is to provide a method for preparing a double-layer composite fabric for visualizing sweat self-pumping.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] A method for preparing a double-layer composite fabric for visualizing sweat self-pumping, comprising the steps of:

[0008] (1) Hydrophilic core-sheath composite yarn was prepared by conjugate electrospinning and hydrothermal treatment, and hydrophobic core-sheath composite yarn was prepared by conjugate electrospinning, pretreatment liquid impregnation and hydrothermal treatment.

[0009] (2) Using hydrophilic core-sheath composite yarn and hydrophobic core-sheath composite yarn as weft yarns and ordinary yarn as warp yarns, the composite fabric is woven according to the double-layer fabric structure to form a hydrophilic layer and a hydrophobic layer, which presents an asymmetrical wetting state on both sides of the fabric.

[0010] (3) Using metal wire as core wire electrode, a yarn-shaped power generation device with core sheath structure is prepared and embedded with the hydrophilic layer of double-layer fabric. The power generation performance of sweat enriched in the hydrophilic layer is detected, and the electrical signal of sweat-induced power generation is converted by the flow potential to visualize the performance of the double-layer fabric in pumping sweat.

[0011] Compared with the prior art, the present invention has the following beneficial effects:

[0012] (1) This invention introduces nanofibers into traditional yarns to form a scale difference, constructs multi-scale composite yarns, and then weaves them into double-layer fabrics with surface wetting differences, which enhances the directional transport performance of sweat and brings new research ideas for functional applications in sweat management.

[0013] (2) By seamlessly integrating sweat directional transport technology with traditional woven fabrics and achieving multi-level gradient wettability differences in the thickness direction, the directional transport behavior of sweat in multi-scale composite fabrics can be visualized through signal conversion, thereby promoting the expansion of more efficient utilization scenarios for water energy. Attached Figure Description

[0014] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings related to this invention described below are only some embodiments of this invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0015] Figure 1 The images show scanning electron microscope images of the hydrophilic PAN / ZnO composite yarn and the hydrophobic PAN / ZnO composite yarn prepared in Example 1 of the present invention, wherein (a1, a2) are hydrophilic PAN / ZnO composite yarns and (b1, b2) are hydrophobic PAN / ZnO composite yarns.

[0016] Figure 2 This is a graph showing the change in water contact angle of the hydrophilic PAN / ZnO composite yarn prepared in Example 1 of this invention;

[0017] Figure 3 This is a diagram of the microstructure of the double-layer fabric prepared in Example 1 of the present invention; Detailed Implementation

[0018] The present application will be described in detail below with reference to specific embodiments, but the implementation examples of the present invention are not limited thereto.

[0019] A method for preparing a double-layer composite fabric for visualizing sweat self-pumping according to the present invention includes the following steps:

[0020] (1) Hydrophilic core-sheath composite yarn was prepared by conjugate electrospinning and hydrothermal treatment, and hydrophobic core-sheath composite yarn was prepared by conjugate electrospinning, pretreatment liquid impregnation and hydrothermal treatment.

[0021] (2) Then, using hydrophilic composite yarn and hydrophobic composite yarn as weft yarn and ordinary yarn as warp yarn, the composite fabric hydrophilic layer and hydrophobic layer are woven according to the double-layer fabric structure, and the fabric presents an asymmetrical wetting state on both sides.

[0022] (3) Using metal wire as core wire electrode, a yarn-shaped power generation device with core sheath structure is prepared. It is embedded with the hydrophilic layer of the double-layer fabric and the power generation performance of the sweat enriched in the hydrophilic layer is detected. The performance of the double-layer fabric in pumping sweat is visualized and the signal is converted.

[0023] Preferably, in step (1), the hydrophilic core-sheath composite yarn has ordinary yarn as the core yarn and hydrophilic polyacrylonitrile (PAN) / zinc oxide (ZnO) nanofibers as the sheath covering yarn, and the hydrophobic core-sheath composite yarn has ordinary yarn as the core yarn and hydrophobic polyvinylidene fluoride (PVDF) / zinc oxide (ZnO) or hydrophobic PAN / ZnO nanofibers as the sheath covering yarn, thus forming a difference in wettability.

[0024] In some examples, the core yarn of the hydrophilic core-sheath composite yarn and the hydrophobic core-sheath composite yarn is a common natural fiber or chemical fiber yarn.

[0025] In some examples, the fiber material of the core yarn is one or more of cotton, linen, silk, wool, viscose fiber, regenerated cellulose fiber, or polyester, nylon, acrylic, polypropylene, spandex, vinylon, and chlorofiber. The fiber type of the core yarn can be pure yarn, blended yarn, twisted yarn, or mixed fiber yarn. The fiber length of the core yarn is filament yarn, staple yarn, or a composite yarn of filament and staple fiber.

[0026] Preferably, the hydrophilic PAN / ZnO nanofiber sheath is prepared as follows: First, a composite yarn coated with PAN / zinc salt nanofibers is obtained by conjugate electrospinning, with a spinning solution concentration of 7-18 wt%; then, the obtained coated yarn is heat-treated at a temperature of 100-170℃ for 0.5-24 h; then, the heat-treated fiber is placed in a growth solution for hydrothermal treatment at a temperature range of 60-150℃ for 0.5-20 h, and then dried in an oven to obtain the hydrophilic PAN / ZnO composite yarn.

[0027] Preferably, the growth solution is made by adding hexamethylenetetramine (HMAT) and any one of zinc chloride, zinc acetate, or zinc nitrate in a molar ratio of 1:1 to 3:1 to deionized water and stirring until homogeneous. The total molar volume of the growth solution is 0.01 to 0.5 mol / L, and the ammonia content is 10% to 70%.

[0028] The ZnO morphology prepared on the core yarn of the hydrophilic PAN / ZnO composite yarn includes hollow, sheet, and rod shapes, and the ZnO diameter is 300nm to 10μm.

[0029] Preferably, the hydrophobic PVDF / ZnO nanofiber or PAN / ZnO nanofiber sheath is prepared as follows: First, a composite yarn coated with PVDF / zinc salt or PAN / zinc salt nanofibers is obtained by conjugate electrospinning, wherein the concentration of the PVDF / zinc salt conjugate electrospinning solution is 9-26 wt%, and the concentration of the PAN / zinc salt conjugate electrospinning solution is 7-18 wt%. Then, the PVDF / zinc salt or PAN / zinc salt composite yarn is immersed in a pretreatment solution for 5-60 minutes, removed and treated in a muffle furnace at 90-200°C for 5-60 minutes, repeated 2-20 times. The composite yarn after repeated treatment is then placed in a growth solution at 80-200°C for 2-30 hours and dried in an oven to obtain the hydrophobic PVDF / ZnO or PAN / ZnO composite yarn.

[0030] Preferably, the pretreatment solution for obtaining the hydrophobic PVDF / ZnO or PAN / ZnO composite yarn is an ethanol solution of anhydrous zinc acetate, with a molar concentration of 0.001–0.05 mol / L. The growth solution is deionized water with HTMA added at a molar ratio of 1:1 and any one of zinc chloride, zinc acetate, or zinc nitrate, and stirred until homogeneous. The dried PVDF / ZnO or PAN / ZnO composite yarn is then immersed in an ethanol solution of magnesium stearate, with a mass fraction of 0.1%–10% in the ethanol solution, to enhance the durability of the yarn.

[0031] The ZnO morphology prepared on the core yarn of the hydrophobic PVDF / ZnO or PAN / ZnO composite yarn is fine needle-like, with a ZnO diameter of 1nm to 300nm. The ZnO diameter on the surface of the hydrophobic composite yarn is smaller than that on the surface of the hydrophilic composite yarn, resulting in different surface roughness of the hydrophilic and hydrophobic structures.

[0032] In some examples, the solvent of the PAN / zinc salt or PVDF / zinc salt electrospinning solution is one of N,N dimethylformamide or N,N dimethylacetamide, and the zinc salt is one of zinc chloride, zinc acetate or zinc nitrate, wherein the ratio of PAN or PVDF to zinc salt is 1:2 to 20:1.

[0033] In some examples, in step (2), hydrophilic PAN / ZnO composite yarn is selected as the outer weft, hydrophobic PVDF / ZnO or PAN / ZnO composite yarn is selected as the inner weft, and ordinary yarn is selected as the outer and inner warp yarns. The outer and inner fabrics are connected together by joining the inner warp and the outer weft, and the outer warp and the inner weft, so that the asymmetrical wetting state is achieved on both sides of the fabric at the same time. The corresponding on-machine weaving parameters are adjusted to weave a double-layer fabric.

[0034] In some examples, the core yarn of the hydrophilic PAN / ZnO composite yarn and the core yarn of the hydrophobic PVDF / ZnO or PAN / ZnO composite yarn can be the same or different, but at different times the hydrophilic properties of the core yarn of the hydrophilic PAN / ZnO composite yarn are better than those of the core yarn of the hydrophobic PVDF / ZnO or PAN / ZnO composite yarn.

[0035] In some examples, the ordinary yarns of the outer and inner warp yarns can be the same or different, but at different times the hydrophilicity of the outer warp yarn is better than that of the inner warp yarn.

[0036] Preferably, in step (3), metal wire A is used as the core electrode, and PAN nanofibers are wrapped around the core electrode A by conjugate electrospinning. Metal wire B is used as another electrode and is inserted into the surface of PAN nanofibers. Then, PAN nanofibers are wrapped around the metal electrode B by conjugate electrospinning to obtain a yarn-shaped electronic device.

[0037] Preferably, the metal wires A and B of the yarn-shaped electronic device are two of aluminum, zinc, iron, tin, copper, silver, platinum, and gold. In electrochemistry, the metal with the higher activity level is the negative electrode, and the metal with the lower activity level is the positive electrode.

[0038] In some examples, the yarn-shaped electronic device is embedded with the hydrophilic layer of a double-layer fabric, and a multimeter is used to connect the positive and negative electrodes of different metal wires at both ends and record the data in real time, so as to analyze the wetting and fluidity of sweat based on the principle of flow potential.

[0039] Preferably, when the yarn-shaped electronic device is embedded in the hydrophilic layer of the double-layer fabric, multiple device units can be connected in series or in parallel through a "staggered and orderly stacking" method to simultaneously increase the voltage and current output through the large-scale integration of the devices.

[0040] Example 1

[0041] A method for preparing a double-layer composite fabric for visualizing sweat self-pumping, comprising the following steps:

[0042] (1) Prepare a PAN / Zn(AC)2 / polyester composite yarn by preparing a PAN / zinc acetate / N,N-dimethylacetamide spinning solution with a concentration of 14wt%, adjusting the ratio of PAN to zinc acetate (Zn(AC)2) to 6:1, using 59.02tex polyester as the core yarn, and using a 7kV positive and negative high voltage power supply for electrospinning and a spinning distance of 12.5cm.

[0043] PAN / Zn(AC)2 / polyester composite yarn was heat-treated in a muffle furnace at 130℃ for 10 hours to grow a ZnO seed layer. HMAT and zinc chloride (molar ratio 1:1) were added to deionized water and stirred until homogeneous. Then, 30% ammonia solution was added to prepare a growth solution with a total molar concentration of 0.15 mol / L. The heat-treated composite yarn with the ZnO seed layer was then placed in the growth solution and treated in a muffle furnace at 98℃ for 10 hours. The yarn was then washed with water and dried in an oven. Figure 1 In the figures a1 and a2, the scanning electron microscope images of the hydrophilic PAN / ZnO composite yarn prepared in the embodiments of the present invention are shown. Figure 2 This is a graph showing the variation of the water contact angle of the hydrophilic PAN / ZnO composite yarn.

[0044] PAN / Zn(AC)2 / polyester composite yarn was immersed in a 0.01 mol / L anhydrous zinc acetate / ethanol solution for 10 min as a pretreatment solution, then treated in a muffle furnace at 150℃ for 10 min, repeated three times. The yarn after this repeated treatment was then placed in a growth solution at 93℃ for 4 h. The growth solution was a mixture of equal parts 0.03 mol / L HMAT aqueous solution and 0.03 mol / L zinc acetate aqueous solution. Finally, the washed and dried composite yarn was immersed in a mixture of 0.3 g magnesium stearate and 50 mL ethanol to obtain a hydrophobic PAN / ZnO / polyester composite yarn. Figure 1 b1 and b2 are scanning electron microscope images of the hydrophobic PAN / ZnO composite yarn prepared in the embodiments of the present invention.

[0045] (2) Hydrophilic PAN / ZnO / polyester composite yarn is selected as the outer weft, and hydrophobic PAN / ZnO / polyester composite yarn is selected as the inner weft. Ordinary yarn is used as the outer and inner warp yarns. The outer and inner fabrics are connected together by joining the inner warp with the outer weft and the outer warp with the inner weft. Figure 3 This is a diagram illustrating the fabric structure used in the double-layer fabric of this invention. By simultaneously achieving asymmetrical wetting on both sides of the fabric and adjusting the corresponding weaving parameters, a double-layer fabric is woven.

[0046] (3) Using zinc wire as the negative electrode core wire, PAN nanofibers were prepared by coating 14wt% PAN / N,N-dimethylacetamide spinning solution on the zinc wire electrode through conjugate electrospinning. Copper wire was used as the positive electrode and inserted into the surface of PAN nanofibers. PAN nanofibers were then coated on the copper wire through conjugate electrospinning to obtain a yarn-shaped electronic device. The obtained yarn-shaped electronic device was embedded in the hydrophilic layer of a double-layer fabric. The induced power generation performance of the sweat enriched in the hydrophilic layer was detected, and the self-pumping performance of the double-layer fabric was visualized and converted into a signal.

[0047] Example 2

[0048] A method for preparing a double-layer composite fabric for visualizing sweat self-pumping, comprising the following steps:

[0049] (1) Prepare a PAN / zinc acetate / N,N-dimethylacetamide spinning solution with a concentration of 14wt%, adjust the ratio of PAN to zinc acetate (Zn(AC)2) to 5:1, use 28.12tex polyester as the core yarn, use a 7kV positive and negative high voltage power supply for electrospinning and a spinning distance of 12.5cm to prepare PAN / Zn(AC)2 / polyester composite yarn;

[0050] PAN / Zn(AC)2 / polyester composite yarn was heat-treated in a muffle furnace at 130℃ for 10 hours to grow a ZnO seed layer. HMAT and zinc chloride with a molar ratio of 1:1 were added to deionized water and stirred evenly. Then, 10% ammonia water was added to the solution to prepare a growth solution with a total molar concentration of 0.1mol / L. The composite yarn with the ZnO seed layer grown after heat treatment was placed in the growth solution and treated in a muffle furnace at 100℃ for 8 hours. The yarn was then washed with clean water and dried in an oven. A PVDF / zinc acetate / N,N-dimethylacetamide spinning solution with a concentration of 10wt% was prepared. The ratio of PVDF to zinc acetate Zn(AC)2 was adjusted to 2:1. 59.02tex polyester was used as the core yarn. The electrospinning power supply was 8kV and the spinning distance was 15cm to prepare PVDF / Zn(AC)2 / polyester composite yarn.

[0051] The PVDF / Zn(AC)2 / polyester composite yarn was immersed in a 0.01 mol / L anhydrous zinc acetate / ethanol solution for 10 min as a pretreatment solution, and then treated in a muffle furnace at 130℃ for 10 min. This process was repeated three times. The yarn after repeated treatment was then placed in a growth solution at 100℃ for 4 h. The growth solution was a mixture of equal parts of 0.03 mol / L HMAT aqueous solution and 0.03 mol / L zinc acetate aqueous solution. Finally, the washed and dried composite yarn was placed in a mixed soaking solution of 0.3 g magnesium stearate and 50 mL ethanol to obtain a hydrophobic ZnO / PVDF / polyester composite yarn.

[0052] (2) Select hydrophilic PAN / ZnO / polyester composite yarn as the outer weft, hydrophobic ZnO / PVDF / polyester composite yarn as the inner weft, and ordinary yarn as the outer and inner warp yarns. Connect the outer and inner fabrics together by joining the inner warp and the outer weft, and the outer warp and the inner weft. Asymmetrical wetting is achieved on both sides of the fabric at the same time. Adjust the corresponding weaving parameters to weave a double-layer fabric.

[0053] (3) Using zinc wire as the negative electrode core wire, PAN nanofibers were prepared by coating 14wt% PAN / N,N-dimethylacetamide spinning solution on the zinc wire electrode through conjugate electrospinning. Silver wire was used as the positive electrode and inserted into the surface of PAN nanofibers. PAN nanofibers were then coated on the copper wire through conjugate electrospinning to obtain a yarn-shaped electronic device. The obtained yarn-shaped electronic device was embedded in the hydrophilic layer of a double-layer fabric. The induced power generation performance of the sweat enriched in the hydrophilic layer was detected, and the self-pumping performance of the double-layer fabric was visualized and converted into a signal.

[0054] Example 3

[0055] A method for preparing a double-layer composite fabric for visualizing sweat self-pumping, comprising the following steps:

[0056] (1) Prepare a PAN / zinc acetate / N,N-dimethylacetamide spinning solution with a concentration of 13wt%, adjust the ratio of PAN to zinc acetate (Zn(AC)2) to 7:1, use 18.45tex×2tex polyester as the core yarn, use an electrospinning positive and negative high voltage power supply of 8kV and a spinning distance of 12.5cm to prepare PAN / Zn(AC)2 / polyester composite yarn;

[0057] PAN / Zn(AC)2 / polyester composite yarn was heat-treated in a muffle furnace at 120℃ for 8 hours to grow a ZnO seed layer. HMAT and zinc chloride (molar ratio 1:1) were added to deionized water and stirred until homogeneous. Then, 20% ammonia was added to the solution to prepare a growth solution with a total molar concentration of 0.15 mol / L. The heat-treated composite yarn with the ZnO seed layer was then placed in the growth solution and placed in a muffle furnace at 110℃. After 6 hours of treatment, the yarn was washed with clean water and dried in an oven. A PVDF / ZnO / polyester composite yarn was prepared with a concentration of 12wt% and the ratio of PVDF to zinc acetate (Zn(AC)2) was adjusted to 4:1. 18.45tex×2tex polyester was used as the core yarn. The electrospinning power supply was 9kV and the spinning distance was 20cm. PVDF / Zn(AC)2 / polyester composite yarn was prepared.

[0058] The PVDF / Zn(AC)2 / polyester composite yarn was immersed in a 0.02 mol / L anhydrous zinc acetate / ethanol solution for 12 min as a pretreatment solution, and then treated in a muffle furnace at 120℃ for 20 min. This process was repeated three times. The yarn after repeated treatment was then placed in a growth solution at 100℃ for 5 h. The growth solution was a mixture of equal parts of 0.035 mol / L HMAT aqueous solution and 0.035 mol / L zinc acetate aqueous solution. Finally, the washed and dried composite yarn was placed in a mixed soaking solution of 0.3 g magnesium stearate and 60 mL ethanol to obtain the hydrophobic ZnO / PVDF / polyester composite yarn.

[0059] (2) Select hydrophilic PAN / ZnO / polyester composite yarn as the outer weft, hydrophobic ZnO / PVDF / polyester composite yarn as the inner weft, and ordinary yarn as the outer and inner warp yarns. Connect the outer and inner fabrics together by joining the inner warp and the outer weft, and the outer warp and the inner weft. Asymmetrical wetting is achieved on both sides of the fabric at the same time. Adjust the corresponding weaving parameters to weave a double-layer fabric.

[0060] (3) Using aluminum wire as the negative electrode core wire, PAN nanofibers were prepared by coating 12wt% PAN / N,N-dimethylacetamide spinning solution on the zinc wire electrode through conjugate electrospinning. Copper wire was used as the positive electrode and inserted into the surface of the PAN nanofibers. PAN nanofibers were then coated on the copper wire through conjugate electrospinning to obtain a yarn-shaped electronic device. Five yarn-shaped electronic devices were prepared in series and embedded in the hydrophilic layer of a double-layer fabric. The induced power generation performance of the sweat enriched in the hydrophilic layer was detected, and the self-pumping performance of the double-layer fabric was visualized and converted into a signal.

[0061] Although specific embodiments of the present invention have been described in detail by way of examples, those skilled in the art should understand that the above examples are for illustrative purposes only and are not intended to limit the scope of the invention. Those skilled in the art can make various modifications or additions to the described specific embodiments or use similar methods to replace them, without departing from the direction of the invention or exceeding the scope defined by the appended claims. Those skilled in the art should understand that any modifications, equivalent substitutions, improvements, etc., made to the above embodiments based on the technical essence of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a double-layer composite fabric for visualizing sweat self-pumping, characterized in that, The method steps are as follows: Step (1) Prepare hydrophilic core-sheath composite yarn by conjugate electrospinning and hydrothermal treatment, and prepare hydrophobic core-sheath composite yarn by conjugate electrospinning, pretreatment liquid impregnation and hydrothermal treatment. In step (1), the hydrophilic core-sheath composite yarn is a yarn with ordinary yarn as the core and hydrophilic polyacrylonitrile PAN / zinc oxide ZnO nanofibers as the sheath, and the hydrophobic core-sheath composite yarn is a yarn with ordinary yarn as the core and hydrophobic polyvinylidene fluoride PVDF / zinc oxide ZnO nanofibers as the sheath. The ZnO morphology prepared on the core yarn of the hydrophilic polyacrylonitrile (PAN) / zinc oxide (ZnO) nanofiber composite yarn has a hollow, sheet-like or rod-like shape, and the ZnO diameter is 300 nm to 10 μm. The ZnO morphology prepared on the core yarn of the hydrophobic polyvinylidene fluoride (PVDF) / zinc oxide (ZnO) nanofiber composite yarn is fine needle-like, with a ZnO diameter of 1 nm to 300 nm. The ZnO diameter on the surface of the hydrophobic composite yarn is smaller than that on the surface of the hydrophilic composite yarn, resulting in different surface roughness of the hydrophilic and hydrophobic structures. Step (2) Use hydrophilic core-sheath composite yarn and hydrophobic core-sheath composite yarn as weft yarns and ordinary yarn as warp yarns to weave the composite fabric hydrophilic layer and hydrophobic layer according to the double-layer fabric structure, so that the fabric presents an asymmetrical wetting state on both sides. Step (3) Using a metal wire as the core electrode, a yarn-shaped power generation device with a core-sheath structure is prepared and embedded into the hydrophilic layer of the double-layer fabric. The power generation performance of the sweat enriched in the hydrophilic layer is detected, and the electrical signal of the sweat-induced power generation is converted by the flow potential to visualize the performance of the double-layer fabric in pumping sweat. The yarn-shaped electronic device is obtained by: using metal wire A as the core electrode, polyacrylonitrile PAN nanofibers are wrapped around the core electrode A by conjugated electrospinning, and metal wire B is inserted into the surface of polyacrylonitrile PAN nanofibers as another electrode. Then, polyacrylonitrile PAN nanofibers are wrapped around the metal electrode B by conjugated electrospinning to obtain the yarn-shaped electronic device. The process for obtaining the hydrophobic polyvinylidene fluoride (PVDF) / zinc oxide (ZnO) nanofiber skin is as follows: First, PVDF / zinc salt nanofiber-coated composite yarns were obtained through conjugate electrospinning, with the concentration of the PVDF / zinc salt conjugate electrospinning solution ranging from 9 to 26 wt%. Then, the PVDF / zinc salt composite yarn is soaked in the pretreatment solution for 5-60 minutes, taken out and treated in a muffle furnace at 90-200℃ for 5-60 minutes, and repeated 2-20 times. The composite yarn after repeated treatment is then placed in the growth solution at 80–200 °C for 2–30 h and dried in an oven to obtain hydrophobic PVDF / ZnO composite yarn. The pretreatment solution was an ethanol solution of anhydrous zinc acetate, and the molar concentration of the pretreatment solution was 0.001–0.05 mol / L. The growth solution is deionized water with hexamethylenetetramine added in a molar ratio of 1:1 and any one of zinc chloride, zinc acetate, or zinc nitrate, and stirred evenly. The dried PVDF / ZnO composite yarn is immersed in a magnesium stearate-ethanol mixture to enhance the durability of the yarn. The mass fraction of magnesium stearate in ethanol is 0.1% to 10%.

2. The method for preparing a double-layer composite fabric for visualizing sweat self-pumping according to claim 1, characterized in that: The process for obtaining the hydrophilic polyacrylonitrile (PAN) / zinc oxide (ZnO) nanofiber skin is as follows: First, a composite yarn coated with polyacrylonitrile / zinc salt nanofibers was obtained by conjugated electrospinning, with a spinning solution concentration of 7–18 wt%. The resulting covered yarn is then heat-treated at a temperature of 100–170 °C for 0.5–24 h. The heat-treated fibers are then placed in a growth solution for hydrothermal treatment. The temperature range of the hydrothermal reaction is 60–150 °C, and the time is 0.5–20 h. The fibers are then dried in an oven to obtain hydrophilic PAN / ZnO composite yarn.

3. The method for preparing a double-layer composite fabric for visualizing sweat self-pumping according to claim 2, characterized in that: The growth solution is made by adding hexamethylenetetramine and any one of zinc chloride, zinc acetate, or zinc nitrate in a molar ratio of 1:1 to 3:1 to deionized water and stirring until homogeneous. The total molar amount of the growth solution is 0.01 to 0.5 mol / L, and the ammonia content is 10% to 70%.

4. The method for preparing a double-layer composite fabric for visualizing sweat self-pumping according to claim 1, characterized in that: In step (2), hydrophilic polyacrylonitrile (PAN) / zinc oxide (ZnO) composite yarn is selected as the outer weft, hydrophobic polyvinylidene fluoride (PVDF) / zinc oxide (ZnO) composite yarn is selected as the inner weft, and ordinary yarn is selected as the outer and inner warp yarns. The outer and inner fabrics are connected together by joining the inner warp and the outer weft, and the outer warp and the inner weft, so that the asymmetrical wetting state is achieved on both sides of the fabric at the same time. The corresponding on-machine weaving parameters are adjusted to weave a double-layer fabric.

5. The method for preparing a double-layer composite fabric for visualizing sweat self-pumping according to claim 4, characterized in that: The metal wires A and B of the yarn-shaped electronic device are two of aluminum, zinc, iron, tin, copper, silver, platinum, and gold. In electrochemistry, the metal with the higher activity level is the negative electrode, and the metal with the lower activity level is the positive electrode.

6. The method for preparing a double-layer composite fabric for visualizing sweat self-pumping according to claim 4, characterized in that: When the yarn-shaped electronic device is embedded in the hydrophilic layer of the double-layer fabric, multiple device units are connected in series or in parallel through staggered and orderly stacking, so as to increase the voltage and current output simultaneously through the large-scale integration of the device.

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