Antibacterial and unidirectional moisture-conducting piezoelectric sensing fabric and preparation method and application thereof

Abstract

The application discloses an antibacterial and one-way moisture-conducting piezoelectric sensing fabric and a preparation method and application thereof, and the piezoelectric sensing fabric is a three-way orthogonal structure, and the piezoelectric sensing fabric is sequentially provided with a hydrophobic layer, a piezoelectric material layer and a hydrophilic layer in the thickness direction, the hydrophobic layer is made of polyester yarn, and the hydrophilic layer is made of cotton yarn; the piezoelectric material layer comprises a piezoelectric layer and sensing layers located on both sides of the piezoelectric layer; the piezoelectric layer is made of nanofiber covering yarn, the nanofiber covering yarn is polyvinylidene fluoride-zinc oxide nanofiber covering yarn prepared by a conjugate electrospinning process; the sensing layer adjacent to the hydrophobic layer is provided with conductive yarn and polyester yarn in an interval mode, and the sensing layer adjacent to the hydrophilic layer is provided with conductive yarn and cotton yarn in an interval mode, and the conductive yarn is polyvinylidene fluoride-zinc oxide piezoelectric yarn prepared by a conjugate electrospinning process and a two-dimensional weaving process. The piezoelectric sensing fabric disclosed by the application has good piezoelectric performance, antibacterial effect, good mechanical properties, one-way moisture-conducting function and good comfort.

Description

Technical Field

[0001] This invention belongs to the field of piezoelectric sensing technology, and in particular relates to an antibacterial and unidirectional moisture-wicking piezoelectric sensing fabric, its preparation method, and its application. Background Technology

[0002] Human sweat glands secrete sweat containing large amounts of glucose, vitamins, and salts. When sweat is produced on the skin's surface, fabrics cannot quickly remove and evaporate it, leading to a sticky, damp, and cold feeling, and promoting bacterial growth on the skin, thus threatening human health. Commonly used antibacterial strategies include antibiotics and electro-stimulation (ES) to inhibit bacterial growth and achieve antibacterial effects. However, overuse of antibiotics can lead to antibiotic resistance, and electroporation requires additional power, resulting in high energy consumption and costs. Therefore, efforts are being made to develop new materials that can replace antibiotics and traditional antibacterial agents. For example, the literature "Durable antibacterial and temperature-regulated core-spun yarns for textile health and comfort applications" describes micro-nano structured yarns and antibacterial products with excellent electrothermal, photothermal, antibacterial, and sustained-release properties. However, these antibacterial products have poor mechanical strength, cannot be used for extended periods, have poor comfort, are not suitable for human use, and require additional power, thus limiting their application in the textile industry.

[0003] The development of piezoelectric materials has provided researchers with new directions. Piezoelectric catalysts can release electrons under controlled stimulation, catalyzing the redox reactions of substrates (such as water and oxygen) to generate reactive oxygen species, which can then sterilize without tissue penetration limitations. Therefore, in health and safety protection, developing piezoelectric sensing fabrics with good piezoelectric properties and antibacterial effects, requiring no additional power source, while also possessing good mechanical properties, high efficiency and durability, and the ability to effectively wick away sweat, ensuring good breathability and comfort, is a direction that researchers need to strive for. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the technical problem this invention aims to solve is to provide an antibacterial and unidirectional moisture-wicking piezoelectric sensing fabric that, while possessing excellent piezoelectric properties and antibacterial effects, also exhibits good mechanical properties, high efficiency and durability, and unidirectional moisture-wicking function to promptly wick away sweat, providing good comfort and breathability. This invention also proposes a method for preparing the antibacterial and unidirectional moisture-wicking piezoelectric sensing fabric and its applications.

[0005] To achieve the above objectives, the technical solution of the present invention is implemented as follows:

[0006] This invention provides an antibacterial and unidirectional moisture-wicking piezoelectric sensing fabric. The piezoelectric sensing fabric has a triaxial orthogonal structure, consisting of multiple layers of warp and weft yarns and Z-yarns that are S-shaped staggered and fixed along the fabric thickness direction. The piezoelectric sensing fabric comprises, in the thickness direction, a hydrophobic layer, a piezoelectric material layer, and a hydrophilic layer, characterized in that:

[0007] The hydrophobic layer is made of polyester yarn;

[0008] The hydrophilic layer is made of cotton yarn;

[0009] The piezoelectric material layer includes a piezoelectric layer in the middle and sensing layers on the upper and lower sides of the piezoelectric layer. The piezoelectric layer is made of nanofiber-coated yarn, which is polyvinylidene fluoride-zinc oxide nanofiber-coated yarn (i.e., PVDF / ZnO nanofiber-coated yarn, which has piezoelectric and antibacterial functions and serves as the piezoelectric layer of the fabric) prepared by conjugated electrospinning. The sensing layer adjacent to the hydrophobic layer is made of conductive yarn and polyester yarn alternately arranged, and the sensing layer adjacent to the hydrophilic layer is made of conductive yarn and cotton yarn alternately arranged (the alternate arrangement avoids short circuits and stabilizes the piezoelectric signal of the sensor). The conductive yarn is polyvinylidene fluoride-zinc oxide nanofiber-coated yarn prepared by conjugated electrospinning, which is then coated with silver-plated nylon yarn by two-dimensional weaving to form polyvinylidene fluoride-zinc oxide piezoelectric yarn (i.e., PVDF / ZnO piezoelectric yarn, which enhances the piezoelectric and antibacterial effect and serves as the sensing layer of the fabric to realize the sensing function).

[0010] The piezoelectric sensing fabric is a multi-layer structure with warp and weft yarns stacked together and then fixed by interlacing Z yarns. The warp and weft yarns are made of various yarns of different materials, forming a sensor structure with a piezoelectric layer in the middle, sensing layers on both sides of the piezoelectric layer, and an insulating layer consisting of a hydrophobic layer and a hydrophilic layer on the outside of the sensing layer.

[0011] The sensing layer and piezoelectric layer of the piezoelectric sensing fabric can excite piezoelectric efficiency under static and dynamic conditions, producing antibacterial effects (polyvinylidene fluoride / zinc oxide nanoparticles are polarized by an electric field or stimulated by external force, and polarized charges accumulate on the relative surface, forming a built-in electric field and attracting free charges in the environment to accumulate on the material surface. The free charges are released from the material surface and react with water and oxygen to generate a large amount of reactive oxygen. The reactive oxygen with strong oxidation-reduction effect reaches the bacterial surface and causes oxidative stress damage to the bacterial cell membrane, intracellular nucleic acid and protein, causing the bacterial cell membrane to rupture and the leakage of intracellular components (oxidized phospholipids, proteins and DNA chains), ultimately leading to bacterial death). Under piezoelectric conditions, it kills most Staphylococcus aureus and Escherichia coli colonizing it, and has a good antibacterial effect.

[0012] The piezoelectric sensing fabric has a hydrophobic layer of polyester yarn in contact with the human body as a skin-friendly inner layer, while the hydrophilic layer of cotton yarn is away from the skin. The nanofiber-coated yarn and conductive yarn in the middle are hydrophobic fibers, which gives the fabric an asymmetrical wetting structure. That is, water or liquid can only be transported along a certain direction of the fabric, and cannot be transported in the opposite direction. Therefore, in actual use and wearing, sweat can be unidirectionally discharged outside the fabric, realizing a one-way moisture-wicking function and good comfort.

[0013] Polyvinylidene fluoride (PVDF)-zinc oxide (ZF) nanofiber-coated yarn, prepared using a conjugate electrospinning process, is directly used as the piezoelectric layer. PVDF-ZF piezoelectric yarn, prepared using both conjugate electrospinning and two-dimensional weaving processes, serves as the sensing layer. During use, no additional piezoelectric layer is required to meet the sensor's piezoelectric requirements. Furthermore, the piezoelectric yarn with a core-sheath structure maintains stable piezoelectric performance during dynamic deformation processes such as bending, twisting, and shaking. Two-dimensional weaving enhances the mechanical properties of the nanofibers, meeting the needs of machine weaving. In addition, the spaced piezoelectric yarns prevent short circuits while meeting the data transmission requirements of the sensing piezoelectric data. Using conductive silver-plated nylon yarn as the core and sheath layers provides excellent conductivity, ensuring a stable and sensitive sensing signal even during sweating. This achieves excellent piezoelectric performance, stable signal output, superior mechanical properties, and high efficiency and durability.

[0014] In some preferred embodiments of the antibacterial and unidirectional moisture-wicking piezoelectric sensing fabric of the present invention, the Z yarn is Coolmax yarn; the Z yarn is arranged in a Z-shaped interval along the warp direction; the cotton yarn is composed of multiple fine cotton yarns.

[0015] Coolmax yarn has high wicking capacity, which can transport moisture and sweat in one direction. Combined with the hydrophilic and hydrophobic properties of polyester and cotton yarns, it forms an asymmetrical wetting structure. Then, through the hollow structure and highly absorbent core layer, the liquid is transported from the hydrophobic side to the hydrophilic side, which further accelerates the rate of unidirectional moisture wicking.

[0016] In some preferred embodiments of the antibacterial and unidirectional moisture-wicking piezoelectric sensing fabric of the present invention, the density of the warp yarns and the Z yarns is 5 to 8 yarns / cm. 2 The density of the weft yarn is 7-10 yarns / cm. 2 This density meets the requirements of regular clothing.

[0017] In some preferred embodiments of the antibacterial and unidirectional moisture-wicking piezoelectric sensing fabric of the present invention, the sensing layer adjacent to the hydrophobic layer is provided with conductive yarn and polyester yarn spaced apart in a 1:1 ratio; the sensing layer adjacent to the hydrophilic layer is provided with conductive yarn and cotton yarn spaced apart in a 1:1 ratio.

[0018] In some preferred embodiments of the antibacterial and unidirectional moisture-wicking piezoelectric sensing fabric of the present invention, the piezoelectric sensing fabric has nine or more layers (an odd number).

[0019] When the piezoelectric sensing fabric has nine layers, it includes five weft layers and four warp layers. The first weft layer, the first warp layer, and the second weft layer are all polyester yarns, forming the hydrophobic layer. The second warp layer consists of conductive yarns spaced between polyester yarns, forming a sensing layer adjacent to the hydrophobic layer. The third weft layer and the third warp layer are nanofiber-coated yarns, forming the piezoelectric layer. The fourth weft layer consists of conductive yarns spaced between cotton yarns, forming a sensing layer adjacent to the hydrophilic layer. The fourth warp layer and the fifth weft layer are cotton yarns, forming the hydrophilic layer.

[0020] When the piezoelectric sensing fabric has an odd number of layers (more than nine), it is based on a nine-layer structure, with the addition of the number of polyester yarn layers in the hydrophobic layer and the number of cotton yarn layers in the hydrophilic layer.

[0021] Another aspect of the present invention provides a method for preparing an antibacterial and unidirectional moisture-wicking piezoelectric sensing fabric, comprising the following steps:

[0022] S1. Preparation of spinning solution: Polyvinylidene fluoride and zinc oxide nanoparticles are added to a mixture of N,N dimethylformamide (DMF) and acetone to prepare a spinning solution;

[0023] S2. Preparation of nanofiber coated yarn: Using silver-plated nylon yarn as the core yarn, the spinning solution of S1 is processed into polyvinylidene fluoride-zinc oxide nanofiber coated yarn through conjugate electrospinning process.

[0024] S3. Preparation of conductive yarn: Using silver-plated nylon yarn as the core yarn, the spinning solution of S1 is processed into polyvinylidene fluoride-zinc oxide nanofiber coated yarn through conjugate electrospinning process; then the polyvinylidene fluoride-zinc oxide nanofiber coated yarn is coated onto the silver-plated nylon yarn through a two-dimensional weaving process to obtain conductive yarn.

[0025] S4. The antibacterial and unidirectional moisture-wicking piezoelectric sensing fabric is obtained by weaving polyester yarn, nanofiber coated yarn prepared in S1, conductive yarn prepared in S2, cotton yarn and Z yarn using a fully automatic rapier loom.

[0026] In some preferred embodiments of the preparation method of the antibacterial and unidirectional moisture-wicking piezoelectric sensing fabric of the present invention, in step S1, polyvinylidene fluoride with a molecular weight of 1,100,000 to 1,200,000 is added to a mixture of N,N dimethylformamide and acetone in a mass ratio of 6 to 8:1 to 4 to obtain a polymer solution with a mass fraction of 8% to 10%. The mixture is stirred until it becomes transparent, and then zinc oxide nanoparticles accounting for 10% to 20% of the mass of polyvinylidene fluoride are added and ultrasonically dispersed to obtain a spinning solution.

[0027] In some preferred embodiments of the preparation method of the antibacterial and unidirectional moisture-wicking piezoelectric sensing fabric of the present invention, in step S2, the conjugate electrospinning power supply voltage is -5KV to 5KV, and the extrusion speed of the spinning solution is 0.3ml·h. -1 ~0.9ml·h -1 The spinning needle spacing is 10cm–15cm, the collecting roller diameter is 15mm–16mm, and the rotation speed is 1.0mm·s. -1 ~2.0mm·s -1 The funnel rotation speed is 300-400 rpm, the ambient temperature is 22℃-28℃, and the ambient humidity is 40%-60%. The electrospinning equipment is manufactured by Nano Instruments.

[0028] In some preferred embodiments of the preparation method of the antibacterial and unidirectional moisture-wicking piezoelectric sensing fabric of the present invention, in S3, the conjugate electrospinning process conditions are the same as those in S2; during the two-dimensional weaving process, the polyvinylidene fluoride-zinc oxide nanofiber coated yarn, which serves as the core yarn, is straightened by the control of a tensioner, and 8 to 14 silver-plated nylon yarns are wound around the core yarn by a two-dimensional weaving machine.

[0029] A third aspect of the present invention provides the use of the antibacterial and unidirectional moisture-wicking piezoelectric sensing fabric and the antibacterial and unidirectional moisture-wicking piezoelectric sensing fabric prepared by the preparation method in insoles.

[0030] Designing antibacterial and unidirectional moisture-wicking piezoelectric sensing fabric into smart insoles that conform to the biomechanical characteristics of users' feet can maximize foot health protection. Sweat transitions from the hydrophobic layer in contact with the skin to the hydrophilic layer, keeping the inner surface of the shoe dry and comfortable during wear. Its piezoelectric antibacterial function inhibits bacterial growth. At the same time, insoles made from this antibacterial and unidirectional moisture-wicking piezoelectric sensing fabric can use piezoelectric yarns as circuit connection electronic components to connect with mobile devices such as mobile apps or smartwatches. When the sole of the foot presses on the fabric, the piezoelectric yarns generate piezoelectric signals, which are transmitted to the external circuit through conductive yarns. The input voltage signal is amplified by the operational amplifier LMV358, transmitted to the analog-to-digital converter of the microcontroller for analysis and processing, and finally transmitted to the terminal to monitor the human movement status.

[0031] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0032] (1) The antibacterial and unidirectional moisture-wicking piezoelectric sensing fabric of the present invention is woven from yarns of various materials, which has good piezoelectric properties and antibacterial effects, while also having good mechanical properties, high efficiency and durability, and unidirectional moisture-wicking function, which can timely wick away sweat, providing good comfort and breathability.

[0033] (2) The present invention uses piezoelectric material polyvinylidene fluoride / zinc oxide nanoparticles to prepare the yarn used for the piezoelectric material layer, so that the sensing layer and piezoelectric layer of the piezoelectric sensing fabric can be excited under static and dynamic conditions to produce antibacterial effect. Under piezoelectric conditions, it kills most of the Staphylococcus aureus and Escherichia coli colonizing it, and has a good antibacterial effect.

[0034] (3) The polyvinylidene fluoride-zinc oxide nanofiber coated yarn prepared by the conjugate electrospinning process is used directly as the piezoelectric layer. The polyvinylidene fluoride-zinc oxide piezoelectric yarn prepared by the conjugate electrospinning process and the two-dimensional weaving process is used as the sensing layer. During use, no additional piezoelectric layer is required to meet the piezoelectric requirements of the sensor. At the same time, the piezoelectric yarn with the core-sheath structure can maintain stable piezoelectric performance during dynamic deformation such as bending, twisting and shaking. The mechanical properties of the nanofiber are improved by two-dimensional weaving, which can meet the needs of weaving. In addition, the piezoelectric yarn is spaced apart, which can avoid short circuits while meeting the data transmission requirements of the sensing piezoelectric data. The use of conductive silver-plated nylon yarn as the core layer and the sheath layer can have good conductivity. The sensor can still have a stable and sensitive sensing signal when sweating. It achieves excellent mechanical properties, high efficiency and durability while having good piezoelectric performance and stable signal output capability.

[0035] (4) The present invention adopts a three-dimensional orthogonal fabric structure design, with multiple layers of yarns in the X, Y and Z directions that are perpendicular to each other. Yarns with different moisture absorption properties are arranged on different layers, so that the fabric has an asymmetrical moisture-wicking structure. In actual use, sweat can be discharged out of the fabric in one direction, realizing the one-way moisture-wicking function and providing good comfort.

[0036] (5) In this invention, a fully automatic rapier loom is used to form a piezoelectric sensing fabric with a three-dimensional orthogonal gradient structure through structural design. The warp and weft yarns are fixed by Z yarn as the fixed yarn according to the S-shaped trajectory. At the same time, it is ensured that the adjacent two Z yarns are staggered in a Z-shape on the horizontal plane, which further stabilizes the position of the yarn in the piezoelectric sensing fabric and ensures the density and air permeability of the piezoelectric sensing fabric. At the same time, polyester yarn and cotton yarn are used to replace the insulating layer, eliminating the encapsulation step required by traditional flexible sensors, which further ensures the air permeability of the sensor fabric. Attached Figure Description

[0037] Figure 1 This is a flowchart illustrating the preparation process of the conductive yarn described in Embodiment 1 of the present invention.

[0038] Figure 2 This is a three-dimensional structural diagram of the piezoelectric sensing fabric described in Embodiment 1 of the present invention;

[0039] Figure 3 This is a schematic diagram of the side structure of the piezoelectric sensing fabric described in Embodiment 1 of the present invention;

[0040] Figure 4 The image shows a three-dimensional ultra-depth-of-field microscope image of the conductive yarn described in Embodiment 1 of the present invention; wherein, (a) is a schematic diagram of the longitudinal three-layer structure of the conductive yarn, and (b) is a schematic diagram of the external structure of the conductive yarn.

[0041] Figure 5 This is a bar chart showing the tensile breaking strength of the nanofiber-coated yarn and conductive yarn described in Embodiment 1 of the present invention.

[0042] Figure 6 This is a test diagram of the piezoelectric properties of the piezoelectric sensing fabric before sweating, as described in Embodiment 1 of the present invention.

[0043] Figure 7 This is a test diagram of the piezoelectric performance of the piezoelectric sensing fabric after sweating, as described in Embodiment 1 of the present invention.

[0044] Figure 8 These are optical images of the wetting conditions of the inner and outer surfaces of the piezoelectric sensing fabric described in Embodiment 1 of the present invention; wherein, (a) is the change of the optical microscopic image of the piezoelectric sensing fabric when water is supplied from the inner layer, and (b) is the change of the optical microscopic image of the piezoelectric sensing fabric when water is supplied from the outer layer.

[0045] Figure 9 This is a comparison diagram of the air permeability of the piezoelectric sensing fabric described in Embodiment 1 of the present invention and commercial denim fabric;

[0046] Figure 10 This is a comparison diagram of the antibacterial effect of the piezoelectric sensing fabric described in Embodiment 1 of the present invention against Staphylococcus aureus.

[0047] Figure 11 This is a comparison diagram of the antibacterial effect of the piezoelectric sensing fabric described in Embodiment 1 of the present invention against Escherichia coli;

[0048] Figure 12 This is a schematic diagram illustrating the effect of applying the piezoelectric sensing fabric described in Embodiment 1 of the present invention to an insole.

[0049] Explanation of reference numerals in the attached diagram: 1-warp yarn, 2-weft yarn, 3-Z yarn, 4-hydrophobic layer, 5-piezoelectric material layer, 6-hydrophilic layer, 7-polyester yarn, 8-cotton yarn, 9-piezoelectric layer, 10-sensing layer, 11-nanofiber coated yarn, 12-conductive yarn. Detailed Implementation

[0050] Specific embodiments of the present invention are given below. These specific embodiments are only used to further illustrate the present invention in detail and do not limit the scope of protection of the present invention.

[0051] Unless otherwise defined, the technical terms used in the following embodiments have the same meanings as commonly understood by those skilled in the art. Unless otherwise specified, the experimental reagents used in the following embodiments are conventional biochemical reagents; and the experimental methods described are conventional methods.

[0052] Example 1

[0053] The preparation of an antibacterial and unidirectional moisture-wicking piezoelectric sensing fabric includes the following steps:

[0054] S1. Preparation of spinning solution: Add polyvinylidene fluoride with a molecular weight of 1,100,000 to a mixture of N,N dimethylformamide and acetone in a mass ratio of 7:3 to obtain a polymer solution with a mass fraction of 10%. Stir magnetically at 70°C for 12 hours until it becomes transparent and homogeneous. Then add zinc oxide nanoparticles accounting for 15% of the mass of polyvinylidene fluoride and ultrasonically disperse for 12 hours to obtain the spinning solution.

[0055] S2. Preparation of nanofiber-coated yarn: Using silver-plated nylon yarn as the core yarn, the spinning solution from S1 is processed into polyvinylidene fluoride-zinc oxide nanofiber-coated yarn through a conjugate electrospinning process; the conjugate electrospinning power supply voltage is -5KV to 5KV, and the extrusion speed of the spinning solution is 0.5ml·h. -1 The spinning needle spacing is 13cm, the collecting roller diameter is 15.12mm, and the rotation speed is 1.0mm·s. -1 The funnel rotation speed was 400 rpm, the ambient temperature was 22℃~28℃, and the ambient humidity was 40%~60%. The electrospinning equipment was used for the production of nano-instruments.

[0056] S3, Preparation of conductive yarn (e.g.) Figure 1 As shown): Using silver-plated nylon yarn as the core yarn, the spinning solution of S1 is processed into polyvinylidene fluoride-zinc oxide nanofiber coated yarn through a conjugate electrospinning process; then, the polyvinylidene fluoride-zinc oxide nanofiber coated yarn is coated onto the silver-plated nylon yarn through a two-dimensional weaving process to obtain conductive yarn; during the two-dimensional weaving process, the polyvinylidene fluoride-zinc oxide nanofiber coated yarn, which serves as the core yarn, is straightened by the control of a tensioner, and 12 silver-plated nylon conductive yarns are tightly and evenly wound around the core yarn through a two-dimensional weaving machine to obtain conductive yarn;

[0057] S4. The antibacterial and unidirectional moisture-wicking piezoelectric sensing fabric is obtained by weaving polyester yarn, nanofiber coated yarn prepared in S1, conductive yarn prepared in S2, cotton yarn and Z yarn using an SGA598 fully automatic rapier loom.

[0058] The structure of antibacterial and unidirectional moisture-wicking piezoelectric sensing fabric is as follows Figure 2 and 3 As shown, the piezoelectric sensing fabric has a three-dimensional orthogonal structure, consisting of multiple layers of warp yarns 1 and weft yarns 2, and Z yarns 3 that are wound in an S-shape and fixed along the fabric thickness direction. The Z yarns 3 are arranged in a Z-shape along the warp yarn direction. The density of warp yarns 1 and Z yarns 3 is 7 ± 1 yarns / cm. 2 The density of weft yarn 2 is 8±1 yarns / cm 2 The piezoelectric sensing fabric consists of a hydrophobic layer 4, a piezoelectric material layer 5, and a hydrophilic layer 6 in the thickness direction.

[0059] The hydrophobic layer 4 is made of polyester yarn 7;

[0060] The hydrophilic layer 6 is made of cotton yarn 8, which is composed of multiple fine cotton yarns;

[0061] The piezoelectric material layer 5 includes a piezoelectric layer 9 in the middle and sensing layers 10 on the upper and lower sides of the piezoelectric layer 9. The piezoelectric layer 9 is made of nanofiber-coated yarn 11, which is polyvinylidene fluoride-zinc oxide nanofiber-coated yarn prepared by conjugated electrospinning. The sensing layer 10 adjacent to the hydrophobic layer 4 is made of conductive yarn 12 and polyester yarn 7 arranged at a 1:1 ratio. The sensing layer 10 adjacent to the hydrophilic layer 6 is made of conductive yarn 12 and cotton yarn 8 arranged at a 1:1 ratio. The conductive yarn 12 is polyvinylidene fluoride-zinc oxide nanofiber-coated yarn prepared by conjugated electrospinning and then coated with silver-plated nylon yarn by two-dimensional weaving process to obtain polyvinylidene fluoride-zinc oxide piezoelectric yarn.

[0062] In this embodiment, when the piezoelectric sensing fabric has nine layers, it includes five layers of weft yarn 2 and four layers of warp yarn 1. The first layer of weft yarn 2, the first layer of warp yarn 1, and the second layer of weft yarn 2 are all polyester yarn 7, forming a hydrophobic layer 4. The second layer of warp yarn 1 consists of conductive yarn 12 and polyester yarn 7 arranged at a 1:1 ratio, forming a sensing layer 10 adjacent to the hydrophobic layer 4. The third layer of weft yarn 2 and the third layer of warp yarn 1 are nanofiber-coated yarn 11, forming a piezoelectric layer 9. The fourth layer of weft yarn 2 consists of conductive yarn 12 and cotton yarn 8 arranged at a 1:1 ratio, forming a sensing layer 10 adjacent to the hydrophilic layer 6. The fourth layer of warp yarn 1 and the fifth layer of weft yarn 2 are cotton yarn 8, forming a hydrophilic layer 6. The Z yarn 3 runs through the entire thickness and is wrapped in an S-shaped staggered manner to fix the warp yarn 1 and weft yarn 2.

[0063] The piezoelectric sensing fabric described in this example uses the arrangement of yarns to create a hydrophobic inner layer and a hydrophilic outer layer, forming a gradient difference in the fabric's wettability. This allows moisture in the inner layer to be directionally transported to the outer layer, while moisture in the outer layer cannot be transported to the inner layer, simultaneously serving as an insulating encapsulation for the piezoelectric material. The conductive yarn in the middle layer and the nanofiber-coated yarn form a "sandwich" structure. When no force is applied, the piezoelectric sensing fabric has no signal output. When an external force is applied to the piezoelectric sensing fabric, the piezoelectric material converts the mechanical stress into a piezoelectric signal. This signal is then output through the conductive yarns above and below the piezoelectric layer, achieving both piezoelectric and antibacterial functions.

[0064] Performance testing:

[0065] like Figure 4 The images shown are three-dimensional ultra-depth-of-field microscope images of conductive yarn. Figure (a) shows the longitudinal three-layer structure of the conductive yarn, in which the core layer (silver-plated nylon, as the internal electrode), the piezoelectric intermediate layer (PVDF / ZnO), and the outermost layer (silver-plated nylon, as the external electrode) are arranged in sequence. The diameter of the nanofiber-coated yarn obtained by conjugated electrospinning ranges from 300 to 400 μm. Figure (b) shows that after two-dimensional weaving, the outermost layer has a dense structure and the yarn is neat and uniform, which can form the external electrode of the piezoelectric yarn and protect the piezoelectric layer in the middle. The diameter of the conductive yarn ranges from 400 to 700 μm, and the mechanical properties are further improved.

[0066] like Figure 5 The figure shows a bar chart of the tensile breaking strength of nanofiber-coated yarn and conductive yarn. Tested according to standard GB9997-1988, the figure shows that both meet certain standards in terms of mechanical properties, thus satisfying the requirements for use and weaving. In the prior art, the maximum stress of two-dimensional braided piezoelectric yarn is only 87.4 MPa, while the strength of the conductive yarn in this embodiment can reach 150 MPa, representing a significant improvement in mechanical properties compared to the prior art. In this embodiment, the conductive yarn provides a certain breaking stress through a two-dimensional braided layer to maintain deformation, improving the tensile breaking capacity of the conductive yarn. The two-dimensional braiding technology provides the outermost conductive layer for the entire piezoelectric yarn while also enhancing its mechanical properties, laying the foundation for its later use and weaving.

[0067] The comparative nanofiber-coated yarn was prepared using the same preparation method as in step S2 of Example 1, except that the funnel rotation speed was 200 rpm. The average diameter of the comparative nanofiber-coated yarn was 579.22 μm, while the average diameter of the nanofiber-coated yarn in this example was 337.75 μm. The tensile breaking strength of the comparative nanofiber-coated yarn was 15.3 MPa, while the tensile breaking strength of the nanofiber-coated yarn in this example was 45.1 MPa. This indicates that the nanofiber-coated yarn prepared under the process parameters of this example has better mechanical properties and a smaller diameter.

[0068] like Figure 6 and 7 The figure shows a comparison of the piezoelectric performance of the antibacterial and unidirectional moisture-wicking piezoelectric sensing fabrics before and after sweating in this embodiment. As can be seen from the figure, under 4Hz excitation, when a force of 8N is applied to the sensor, the fabric's output voltage is 8V. Figure 6 As shown), under the same force, the output voltage increases from 8V to 13V after sweating. Figure 7 As shown in the figure, the test results show that the piezoelectric sensing fabric can stably transmit signals in both of the above conditions. When the human body sweats, the sweat does not weaken the piezoelectric performance of the piezoelectric sensing fabric, but rather enhances it. This is because sweat contains water and chloride ions, which are good conductors of electricity. The faster electron transfer improves the piezoelectric performance of the piezoelectric sensing fabric.

[0069] like Figure 8 The figures show optical images of the wetting conditions of the inner and outer surfaces of the antibacterial and unidirectional moisture-wicking piezoelectric sensing fabric in this embodiment. Figure (a) shows the changes in the optical microscopic image of the piezoelectric sensing fabric when water is supplied from the inner layer, and Figure (b) shows the changes in the optical microscopic image of the piezoelectric sensing fabric when water is supplied from the outer layer. As can be seen from the figures, the droplets in the inner layer are completely absorbed in 3.5s in the initial state, while the droplets in the outer layer are completely absorbed in 0.28s in the initial state. The time required for the same amount of water to penetrate into the inner layer is much longer than the time required to penetrate into the outer layer. These phenomena indicate that the piezoelectric sensing fabric has a hydrophobic inner layer and a hydrophilic outer layer.

[0070] like Figure 9 As shown, the air permeability test of the antibacterial and unidirectional moisture-wicking piezoelectric sensing fabric of this embodiment is shown. Compared with denim fabric, the air permeability of the piezoelectric sensing fabric of this embodiment is 93.42 mm / s, which is higher than that of denim fabric (24.75 mm / s). This indicates that the air permeability of the piezoelectric sensing fabric can meet the air permeability requirements of clothing fabrics.

[0071] like Figure 10 and 11The figure shows the antibacterial and unidirectional moisture-wicking piezoelectric sensing fabric of this embodiment. Antibacterial experiments were conducted according to GB / T20944 "Evaluation of Antibacterial Properties of Textiles - Part 3: Vibration Method". The figure shows that the piezoelectric sensing fabric reduced the number of Staphylococcus aureus and Escherichia coli under vibration and ultrasonic conditions compared to the blank control group. The piezoelectric sensing fabric showed the lowest number of Staphylococcus aureus and Escherichia coli under ultrasonic conditions. The piezoelectricity also has an antibacterial effect on Staphylococcus aureus and Escherichia coli because, under mechanical stimulation, the piezoelectric catalyst… The catalyst can catalyze the redox reaction of water molecules and oxygen to generate reactive oxygen species (ROS). ROS participate in the electron transport chain of bacterial metabolism, thereby damaging the bacterial cell wall and denaturing bacterial proteins. During piezoelectric catalysis, bacteria undergo sufficient levels of oxidative stress, leading to membrane damage. Once the membrane is damaged, toxic substances such as aldehydes and oxides are produced within the bacteria. These products act as second reaction messengers and develop into potential sources of damage to internal proteins, DNA, and other nucleophiles, leading to the death of Staphylococcus aureus and Escherichia coli.

[0072] The response time of the antibacterial and unidirectional moisture-wicking piezoelectric sensing fabric (sensor) prepared in Example 1 was tested using weights and an electrochemical workstation. The sensor and the electrochemical workstation were connected in series. The IT test program was selected in the electrochemical workstation program, and the weights were placed on the sensor. The response time of the sensor to the weights was recorded when the pressure was 3 kPa. The results showed that the response time was 0.3 s and the recovery time was only 0.4 s. The fast response speed and short recovery time to the initial position after being compressed ensured that the strain of the sensor was basically the same under continuous pressure and the output voltage remained unchanged, indicating good piezoelectric performance.

[0073] like Figure 12The diagram illustrates the effect of applying the antibacterial and unidirectional moisture-wicking piezoelectric sensing fabric to an insole in this embodiment. Based on the main pressure distribution areas of the human foot, piezoelectric sensing fabric is placed at the first metatarsal bone (circled), the left side of the foot, the right side of the arch, the left side of the heel, and the right side of the heel, representing the main monitoring areas for human movement. The insole, made of the antibacterial and unidirectional moisture-wicking piezoelectric sensing fabric, serves as a piezoelectric sensor module. During walking, the sole of the foot presses against the fabric, generating a piezoelectric signal through the piezoelectric yarns, which is then transmitted to the external circuit via conductive yarns. The input voltage signal is amplified by an operational amplifier LMV358, transmitted to the analog-to-digital converter of the microcontroller for analysis and processing, and finally transmitted to the terminal to monitor human movement. An Arduino is selected as the microcontroller (MCU), whose main functions are to control the system power supply, detect piezoelectric signals, and enable the level conversion chip. The MCU circuit is powered by a 3.3V battery, and the filtering circuit uses capacitors of different capacitance values ​​to reduce power ripple, ensuring stable chip operation and excellent electromagnetic compatibility. An 8MHz crystal oscillator provides a high-speed clock for chip operation. The chip is reset at a high level, using a typical RC reset circuit. The reset time can be configured according to the RC value. These components constitute the minimum system of the MCU. The MCU mainly controls the system power supply, controls the status of the power indicator light, and detects the battery voltage and the electrical signal of the piezoelectric sensing fabric. The piezoelectric fabric is made into insoles and placed on the soles of shoes. As the piezoelectric fabric is stepped on or squeezed during walking, the energy changes generated by the piezoelectric fabric are detected, allowing for the timely removal of sweat produced by the human body and achieving a bactericidal effect.

[0074] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

[0075] Any aspects not covered in this invention are applicable to existing technologies.

Claims

1. An antibacterial and unidirectional moisture-wicking piezoelectric sensing fabric, wherein the piezoelectric sensing fabric has a triaxial orthogonal structure, consisting of multiple layers of warp and weft yarns and Z yarns wound in an S-shape and fixed along the thickness direction of the fabric; the piezoelectric sensing fabric comprises, in the thickness direction, a hydrophobic layer, a piezoelectric material layer, and a hydrophilic layer, characterized in that: The hydrophobic layer is made of polyester yarn; The hydrophilic layer is made of cotton yarn; The piezoelectric material layer includes a piezoelectric layer in the middle and sensing layers on the upper and lower sides of the piezoelectric layer; the piezoelectric layer is made of nanofiber coated yarn, which is polyvinylidene fluoride-zinc oxide nanofiber coated yarn prepared by conjugated electrospinning process; the sensing layer adjacent to the hydrophobic layer is made of conductive yarn and polyester yarn alternately arranged, and the sensing layer adjacent to the hydrophilic layer is made of conductive yarn and cotton yarn alternately arranged. The conductive yarn is prepared by adding polyvinylidene fluoride with a molecular weight of 1,100,000 to 1,200,000 to a mixture of N,N dimethylformamide and acetone at a mass ratio of 6-8:1-4, to obtain a mass fraction... An 8%–10% polymer solution is stirred and mixed until transparent. Then, 10%–20% of zinc oxide nanoparticles (based on the mass of polyvinylidene fluoride) are added and ultrasonically dispersed to obtain a spinning solution. Using silver-plated nylon yarn as the core yarn, the spinning solution is processed into polyvinylidene fluoride-zinc oxide nanofiber coated yarn through a conjugate electrospinning process. The polyvinylidene fluoride-zinc oxide nanofiber coated yarn is then coated onto the silver-plated nylon yarn through a two-dimensional weaving process to obtain a conductive yarn. During the two-dimensional weaving process, the polyvinylidene fluoride-zinc oxide nanofiber coated yarn, which serves as the core yarn, is straightened under the control of a tensioner, and 8–14 silver-plated nylon yarns are wound around the core yarn using a two-dimensional weaving machine.

2. The antibacterial and unidirectional moisture-wicking piezoelectric sensing fabric according to claim 1, characterized in that: The Z-yarn is Coolmax yarn, and the Z-yarn is arranged in a Z-shape along the warp direction; the cotton yarn is composed of multiple fine cotton yarns.

3. The antibacterial and unidirectional moisture-wicking piezoelectric sensing fabric according to claim 1, characterized in that: The density of the warp yarns and the Z yarns is 5-8 yarns / cm, and the density of the weft yarns is 7-10 yarns / cm.

4. The antibacterial and unidirectional moisture-wicking piezoelectric sensing fabric according to claim 1, characterized in that: The sensing layer adjacent to the hydrophobic layer is made of conductive yarn and polyester yarn arranged alternately in a 1:1 ratio; the sensing layer adjacent to the hydrophilic layer is made of conductive yarn and cotton yarn arranged alternately in a 1:1 ratio.

5. The antibacterial and unidirectional moisture-wicking piezoelectric sensing fabric according to claim 1, characterized in that: The piezoelectric sensing fabric has nine or more layers, which is an odd number. When the piezoelectric sensing fabric has nine layers, it includes five weft layers and four warp layers. The first weft layer, the first warp layer, and the second weft layer are all polyester yarns, forming the hydrophobic layer. The second warp layer consists of conductive yarns spaced between polyester yarns, forming a sensing layer adjacent to the hydrophobic layer. The third weft layer and the third warp layer are nanofiber-coated yarns, forming the piezoelectric layer. The fourth weft layer consists of conductive yarns spaced between cotton yarns, forming a sensing layer adjacent to the hydrophilic layer. The fourth warp layer and the fifth weft layer are cotton yarns, forming the hydrophilic layer. When the piezoelectric sensing fabric has an odd number of layers (more than nine), it is based on a nine-layer structure, with the addition of the number of polyester yarn layers in the hydrophobic layer and the number of cotton yarn layers in the hydrophilic layer.

6. The method for preparing the antibacterial and unidirectional moisture-wicking piezoelectric sensing fabric according to any one of claims 1-5, characterized in that, Includes the following steps: S1. Preparation of spinning solution: Polyvinylidene fluoride and zinc oxide nanoparticles are added to a mixture of N,N dimethylformamide and acetone to prepare a spinning solution. S2. Preparation of nanofiber coated yarn: Using silver-plated nylon yarn as the core yarn, the spinning solution of S1 is processed into polyvinylidene fluoride-zinc oxide nanofiber coated yarn through conjugate electrospinning process. S3. Preparation of conductive yarn: Using silver-plated nylon yarn as the core yarn, the spinning solution of S1 is processed into polyvinylidene fluoride-zinc oxide nanofiber coated yarn through conjugate electrospinning process. The polyvinylidene fluoride-zinc oxide nanofiber coated yarn is then coated with silver-plated nylon yarn through a two-dimensional weaving process to obtain conductive yarn; S4. Polyester yarn, nanofiber coated yarn prepared in S2, conductive yarn prepared in S3, cotton yarn and Z yarn are woven on a fully automatic rapier loom to obtain the antibacterial and unidirectional moisture-wicking piezoelectric sensing fabric.

7. The method for preparing the antibacterial and unidirectional moisture-wicking piezoelectric sensing fabric according to claim 6, characterized in that: In step S1, polyvinylidene fluoride with a molecular weight of 1,100,000 to 1,200,000 is added to a mixture of N,N dimethylformamide and acetone in a mass ratio of 6 to 8:1 to 4 to obtain a polymer solution with a mass fraction of 8% to 10%. The mixture is stirred until it becomes transparent, and then zinc oxide nanoparticles accounting for 10% to 20% of the mass of polyvinylidene fluoride are added and ultrasonically dispersed to obtain a spinning solution.

8. The method for preparing the antibacterial and unidirectional moisture-wicking piezoelectric sensing fabric according to claim 6, characterized in that: In step S2, the conjugate electrospinning power supply voltage is -5KV to 5KV, and the spinning solution extrusion rate is 0.3 ml•h. -1 ~0.9ml•h -1 The spinning needle spacing is 10cm~15cm, the collecting roller diameter is 15mm~16mm, the funnel speed is 300~400rpm, the ambient temperature is 22℃~28℃, and the ambient humidity is 40%~60%.

9. The method for preparing the antibacterial and unidirectional moisture-wicking piezoelectric sensing fabric according to claim 8, characterized in that: In S3, the conjugate electrospinning process conditions are the same as in S2; during the two-dimensional weaving process, the polyvinylidene fluoride-zinc oxide nanofiber coated yarn, which serves as the core yarn, is straightened by the control of a tensioner, and 8 to 14 silver-plated nylon yarns are wound around the core yarn by a two-dimensional weaving machine.

10. Use of an antibacterial and unidirectional moisture-wicking piezoelectric sensing fabric, wherein the piezoelectric sensing fabric is the antibacterial and unidirectional moisture-wicking piezoelectric sensing fabric according to any one of claims 1-5, or the antibacterial and unidirectional moisture-wicking piezoelectric sensing fabric prepared by the preparation method according to any one of claims 6-8, characterized in that: Application in shoe insoles.

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