Multilayer coaxial piezoelectric sensing fiber and method of making same, flexible wearable fabric

Abstract

The application belongs to the technical field of piezoelectric materials, and particularly relates to a multilayer coaxial piezoelectric sensing fiber and a preparation method thereof, and a flexible wearable fabric, which comprises the following steps: step S1, core layer spinning solution and shell layer spinning solution are respectively prepared; step S2, the core layer spinning solution and the shell layer spinning solution are placed on a wet spinning device, and are sequentially solidified, drawn and wound to obtain a composite fiber with a core sheath structure; step S3, the composite fiber is immersed in a reducing agent solution, a large number of composite piezoelectric layers are formed on the surface by stacking, and a multilayer coaxial conductive fiber is obtained; step S4, the conductive fiber is placed in silicon oil, the core layer of the fiber is used as an inner electrode, a silver layer on the surface of the fiber is used as an outer electrode, corona polarization treatment is performed on the composite piezoelectric layer in the middle, and a self-power generation sensing fiber is obtained; and step S5, after polydimethylsiloxane main agent and a curing agent are blended, packaging treatment is performed, and the self-power generation sensing fiber is obtained.

Description

Technical Field

[0001] This invention belongs to the field of piezoelectric material technology, specifically relating to a multilayer coaxial piezoelectric sensing fiber and its preparation method, and a flexible wearable fabric. Background Technology

[0002] Piezoelectric materials are novel smart materials that can convert mechanical energy into electrical energy and can be used as highly sensitive sensors. Lead zirconate titanate (PZT) piezoelectric ceramics, compared to barium titanate and zinc oxide, have higher piezoelectric constants and electromechanical coupling coefficients, and are widely used in the manufacture of electronic devices such as transducers, hydrophones, transformers, and loudspeakers. Traditional piezoelectric ceramics are mostly manufactured using dry pressing, casting, and roll forming. Due to the high brittleness of ceramics, they cannot meet the requirements for flexible sensing materials. Composite piezoelectric thin film materials obtained by combining piezoelectric ceramics with polymers possess both high piezoelectric constants and good flexibility, making them an effective means of preparing flexible sensing materials. However, the addition of a large amount of piezoelectric ceramics reduces the processability of the composite material, and dispersion and polarization are difficult. Therefore, the development of high-performance piezoelectric fiber sensing materials based on piezoelectric ceramics is quite challenging.

[0003] Therefore, overcoming the challenges of processing and polarizing high-performance piezoelectric sensing fibers, and developing highly breathable piezoelectric fabrics based on these fibers, are technical problems that urgently need to be solved in this field.

[0004] It should be noted that the information disclosed in this background section is only for understanding the background technology of the present application concept, and therefore, the above description is not considered to constitute prior art information. Summary of the Invention

[0005] This disclosure provides at least one multilayer coaxial piezoelectric sensing fiber and its preparation method, as well as a flexible wearable fabric.

[0006] In a first aspect, embodiments of this disclosure provide a method for preparing multilayer coaxial piezoelectric sensing fibers, comprising the following steps: Step S1, preparing a core spinning solution and a shell spinning solution respectively, i.e., weighing polyurethane and silane coupling agent and adding them to N,N-dimethylformamide and stirring to dissolve, adding liquid metal after complete dissolution, and ultrasonically dispersing them into micro-nano particles, the dispersion process being carried out in an ice bath, and obtaining a core spinning solution after complete dispersion; weighing lead zirconate titanate and adding it to N,N-dimethylformamide and ultrasonically dispersing, the dispersion process being carried out in an ice bath, then stirring the dispersed lead zirconate titanate suspension, while simultaneously adding polyurethane and silver precursor to the suspension, continuing to stir until completely dissolved, obtaining a shell spinning solution; Step S2, placing the core spinning solution and shell spinning solution on a wet spinning device, and sequentially extruding them through a metering pump and coaxial needle into a coagulation bath for solidification, stretching, and winding, obtaining a composite fiber with a core-sheath structure; Step S3, immersing the composite fiber in a reducing agent solution, so that the Ag in the silver precursor... + The silver gradually migrates to the fiber surface and reacts fully with the reducing agent to generate nano-silver, which accumulates on the surface to form a composite piezoelectric layer. After washing away the excess reducing agent, a multilayer coaxial conductive fiber is obtained. In step S4, the conductive fiber is placed in silicone oil, with the core layer of the fiber as the inner electrode and the silver layer on the fiber surface as the outer electrode. The composite piezoelectric layer in the middle is subjected to corona polarization treatment to obtain a self-generating sensing fiber. In step S5, polydimethylsiloxane main agent and curing agent are mixed and used as coating material. The polarized sensing fiber is encapsulated by dip coating to obtain a self-generating sensing fiber.

[0007] In one optional embodiment, in step S1, the mass ratio of liquid metal to polyurethane in the core spinning solution is (2-4):1; the mass ratio of polyurethane to N,N-dimethylformamide is 1:(5-10); and the mass ratio of silane coupling agent to polyurethane is (1-2):100.

[0008] In one optional embodiment, in step S1, the mass ratio of lead zirconate titanate to polyurethane in the shell spinning solution is (0.7-1.5):1; the mass ratio of polyurethane to N,N-dimethylformamide is 1:(4-8); and the mass ratio of silver precursor to polyurethane is (0.5-1.5):1.

[0009] In one optional embodiment, the ultrasonic dispersion power for preparing the core spinning solution in step S1 is 600-900W, the duration is 10-30min, and the ambient temperature for ultrasonic dispersion is below 4℃; the ultrasonic dispersion power for preparing the shell spinning solution is 800-1100W, the duration is 20-40min, and the ambient temperature for ultrasonic dispersion is below 4℃.

[0010] In one optional embodiment, the silane coupling agent in step S1 comprises any one or more combinations of amino, epoxy, thio, isonitrile ester, and ureosilane; the silver precursor comprises any one or more combinations of silver nitrate, silver acetate, silver trifluoroacetate, and silver citrate.

[0011] In one optional embodiment, the ratio of the extrusion speeds of the core spinning solution and the shell spinning solution in step S2 is (0.5-2):1.

[0012] In one optional embodiment, the reducing agent in step S3 includes any one or more combinations of formaldehyde, glyoxal, ethylenediamine, glucose, potassium sodium tartrate, sodium citrate, hydrazine hydrate, vitamin C, sodium borohydride, and ascorbic acid; and the concentration of the reducing agent is 0.05-0.3 mol / L.

[0013] In one optional embodiment, the polarization voltage in step S4 is 6-15 kV / mm, the polarization temperature is 80-140℃, and the polarization time is 2-10h.

[0014] Secondly, embodiments of this disclosure also provide a multilayer coaxial piezoelectric sensing fiber prepared by the method described above, comprising: an inner electrode, a composite piezoelectric layer, and an outer electrode arranged sequentially from the inside to the outside; wherein the inner electrode comprises a liquid metal composite, the composite piezoelectric layer comprises a piezoelectric ceramic composite, and the outer electrode comprises silver nanoparticles.

[0015] Thirdly, this disclosure also provides a flexible wearable fabric, which is processed from the multilayer coaxial piezoelectric sensing fibers as described above; wherein the processing method includes any one or more combinations of knitting, weaving, braiding and embroidery.

[0016] The beneficial effects of this invention are that the multilayer coaxial piezoelectric sensing fiber and its preparation method, as well as the flexible wearable fabric, directly prepare piezoelectric sensing fibers using a coaxial wet spinning method, overcoming the problem of air impermeability in multilayer film structure piezoelectric sensors. At the same time, the fiberized liquid metal composite is used as the inner electrode of the core layer, and silver ions migrate in the composite system to form the outer electrode of the shell layer using an in-situ reduction method. After polarization treatment, the fiber can be used as a self-generating sensor, with stronger and more stable piezoelectric sensing signal output, and has a wider range of applications after being processed into flexible wearable fabric.

[0017] Other features and advantages of the invention will be set forth in the following description, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention are realized and obtained through the structures particularly pointed out in the description and the drawings.

[0018] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, preferred embodiments are described below in detail with reference to the accompanying drawings. Attached Figure Description

[0019] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0020] Figure 1 A 2000x magnification microstructure diagram of a cross-section of a PZT composite piezoelectric layer of multilayer coaxial piezoelectric sensing fiber provided for embodiments of this disclosure;

[0021] Figure 2 This is a 25,000x magnification microstructure diagram of a cross-section of a PZT composite piezoelectric layer of multilayer coaxial piezoelectric sensing fiber, provided as an embodiment of this disclosure. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0023] As used herein, the phrases “in one embodiment,” “according to one embodiment,” “in some embodiments,” etc., generally refer to the fact that a particular feature, structure, or characteristic following the phrase can be included in at least one embodiment of this disclosure. Therefore, a particular feature, structure, or characteristic can be included in more than one embodiment of this disclosure, such that these phrases do not necessarily refer to the same embodiment. As used herein, the terms “example,” “exemplary,” etc., are used to “serve as an example, instance, or illustration.” Any implementation, aspect, or design described herein as “example” or “exemplary” is not necessarily to be construed as preferred or superior to other implementations, aspects, or designs. Rather, the use of the terms “example,” “exemplary,” etc., is intended to present concepts in a specific manner.

[0024] In this document, exemplary embodiments of the present disclosure will be described in more detail with reference to the accompanying drawings. As used herein, expressions such as “at least one of…” modify the entire list of elements when following a list of elements, rather than individual elements in the list. For example, the expression “at least one of a, b, and c” should be understood to include only a, only b, only c, both a and b, both a and c, both b and c, or all of a, b, and c.

[0025] The terminology used herein is for the purpose of describing specific exemplary configurations only and is not intended to be limiting. As used herein, the singular articles “a,” “an,” and “the” may also be intended to include plural forms unless otherwise clearly stated herein. The terms “comprising,” “including,” and “having” are inclusive and thus specify the presence of features, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, steps, operations, elements, components, and / or combinations thereof. The method steps, processes, and operations described herein should not be construed as requiring them to be performed in the specific order discussed or shown, unless specifically identified as such. Additional or alternative steps may be employed.

[0026] Most of the piezoelectric sensing materials in the currently published patents are multilayer film materials, which do not possess the breathability and moisture permeability required for flexible wearables. Meanwhile, the currently disclosed piezoelectric sensing fibers mostly use self-polarizing piezoelectric materials (such as zinc oxide, barium titanate, and polyvinylidene fluoride).

[0027] Specifically, piezoelectric polymers (such as polyvinylidene fluoride) are used as the matrix, and the fibers are formed by electrospinning. Inorganic piezoelectric powders (such as zinc oxide and barium titanate) are added to enhance the piezoelectric effect. However, because the piezoelectric effect of self-polarized piezoelectric materials is weak and they are prone to depolarization, the resulting piezoelectric fibers generally have weak signal output intensity, limiting their applications.

[0028] Furthermore, all of these piezoelectric sensing fibers require additional electrodes to be connected before they can be used. Patent number CN 116716680A discloses a coaxial wet-spun multifunctional fiber, its preparation method, and its application. It prepares a two-dimensional titanium carbide / polyvinyl alcohol@aramid nanofiber aerogel fiber with a core-sheath structure in a one-step process. However, when this fiber is used as a sensing fiber, it still requires additional electrodes and does not have self-generating power.

[0029] The shortcomings of the above solutions are the result of the inventor's practical experience and careful research. Therefore, the discovery process of the above problems and the solutions proposed in this disclosure below should be considered as the inventor's contribution to this disclosure.

[0030] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0031] The following detailed description of some embodiments of the present invention is provided in conjunction with the accompanying drawings. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0032] This disclosure provides a method for preparing multilayer coaxial piezoelectric sensing fibers, comprising the following steps: Step S1, preparing core layer spinning solution and shell layer spinning solution respectively, i.e., weighing polyurethane and silane coupling agent and adding them to N,N-dimethylformamide and stirring to dissolve. After complete dissolution, liquid metal is added and ultrasonically dispersed into micro / nano particles. The dispersion process is carried out in an ice bath. After complete dispersion, the core layer spinning solution is obtained; weighing lead zirconate titanate and adding it to N,N-dimethylformamide and ultrasonically dispersing it. The dispersion process is carried out in an ice bath. The process is carried out in a bath. Then, a uniformly dispersed lead zirconate titanate suspension is placed on a stirrer and rapidly stirred. Simultaneously, polyurethane and the silver precursor are added to the suspension, and stirring continues until completely dissolved to obtain a shell spinning solution. In step S2, the core spinning solution and shell spinning solution are placed on a wet spinning apparatus and sequentially extruded through a metering pump and coaxial needle into a coagulation bath for solidification, drawing, and winding to obtain a composite fiber with a core-sheath structure. In step S3, the composite fiber is impregnated in a reducing agent solution to allow the Ag in the silver precursor to... + The silver gradually migrates to the fiber surface and reacts fully with the reducing agent to generate nano-silver, which accumulates on the surface to form a composite piezoelectric layer. After washing away the excess reducing agent, a multilayer coaxial conductive fiber is obtained. In step S4, the conductive fiber is placed in silicone oil, with the core layer of the fiber as the inner electrode and the silver layer on the fiber surface as the outer electrode. The composite piezoelectric layer in the middle is subjected to corona polarization treatment to obtain a self-generating sensing fiber. In step S5, polydimethylsiloxane main agent and curing agent are mixed and used as coating material. The polarized sensing fiber is encapsulated by dip coating to obtain a self-generating sensing fiber.

[0033] In some embodiments, specifically, in step S1, the mass ratio of liquid metal to polyurethane in the core spinning solution is (2-4):1; the mass ratio of polyurethane to N,N-dimethylformamide is 1:(5-10); and the mass ratio of silane coupling agent to polyurethane is (1-2):100.

[0034] In some embodiments, specifically, in step S1, the mass ratio of lead zirconate titanate to polyurethane in the shell spinning solution is (0.7-1.5):1; the mass ratio of polyurethane to N,N-dimethylformamide is 1:(4-8); and the mass ratio of silver precursor to polyurethane is (0.5-1.5):1.

[0035] In some embodiments, specifically, in step S1, the ultrasonic dispersion power for preparing the core spinning solution is 600-900W, the duration is 10-30min, and the ambient temperature for ultrasonic dispersion is below 4℃; the ultrasonic dispersion power for preparing the shell spinning solution is 800-1100W, the duration is 20-40min, and the ambient temperature for ultrasonic dispersion is below 4℃.

[0036] In some embodiments, specifically, the silane coupling agent in step S1 includes any one or more combinations of amino, epoxy, thio, isocyanate, and ureosilanes; the silver precursor includes any one or more combinations of silver nitrate, silver acetate, silver trifluoroacetate, and silver citrate.

[0037] In some embodiments, specifically, the ratio of the extrusion speeds of the core spinning solution and the shell spinning solution in step S2 is (0.5-2):1.

[0038] In some embodiments, specifically, the reducing agent in step S3 includes any one or more combinations of formaldehyde, glyoxal, ethylenediamine, glucose, potassium sodium tartrate, sodium citrate, hydrazine hydrate, vitamin C, sodium borohydride, and ascorbic acid; and the concentration of the reducing agent is 0.05-0.3 mol / L.

[0039] In some embodiments, specifically, in step S4, the polarization voltage is 6-15 kV / mm, the polarization temperature is 80-140℃, and the polarization time is 2-10h.

[0040] This disclosure also provides a multilayer coaxial piezoelectric sensing fiber prepared by the method described above, comprising: an inner electrode, a composite piezoelectric layer, and an outer electrode arranged from the inside out; wherein the inner electrode comprises a liquid metal composite, the composite piezoelectric layer comprises a piezoelectric ceramic composite, and the outer electrode comprises silver nanoparticles.

[0041] In some embodiments, specifically, the sensitivity range of the multilayer coaxial piezoelectric sensing fiber is 24.53-37.84 V / N, the average response time is no more than 58 ms, the air permeability is 110-160 mm / s, and the moisture permeability is 8500-9500 g / m²·24h.

[0042] This disclosure also provides a flexible wearable fabric, which is processed from the multilayer coaxial piezoelectric sensing fibers as described above; wherein the processing method includes any one or more combinations of knitting, weaving, braiding and embroidery.

[0043] Example 1

[0044] Step S1: Prepare the core spinning solution and the shell spinning solution respectively, i.e.

[0045] Weigh 100 parts of polyurethane and 1 part of silane coupling agent KH570 and add them to 800 parts of N,N-dimethylformamide and stir to dissolve. After complete dissolution, add 250 parts of liquid metal and disperse with 1000W ultrasonic for 15 minutes to disperse into micro-nano particles. The dispersion process is carried out in an ice bath at 0℃. After complete dispersion, the core layer spinning solution is obtained.

[0046] Weigh 120 parts of lead zirconate titanate and add it to 700 parts of N,N-dimethylformamide for ultrasonic dispersion. Use 1000W ultrasonic dispersion for 20 minutes. The dispersion process is carried out in an ice bath at 0℃. Then, place the uniformly dispersed lead zirconate titanate suspension on a stirrer and stir rapidly. At the same time, add 100 parts of polyurethane and 100 parts of silver trifluoroacetate to the suspension and continue stirring until completely dissolved to obtain the shell spinning solution.

[0047] Step S2: The core spinning solution and the shell spinning solution are placed on a wet spinning device and extruded sequentially into a coagulation bath via a metering pump and a coaxial needle for solidification, stretching, and winding. The extrusion speeds of the core spinning solution and the shell spinning solution are 5 m / min and 4 m / min, respectively, to obtain a composite fiber with a core-sheath structure.

[0048] Step S3: Impregnate the composite fiber in a reducing agent ascorbic acid solution to allow the Ag in the silver precursor to... + Gradually migrate to the fiber surface and react fully with the reducing agent to generate nano-silver, which accumulates in large quantities on the surface to form a composite piezoelectric layer. After washing away the excess reducing agent, a multi-layer coaxial conductive fiber is obtained.

[0049] Step S4: The conductive fiber is placed in silicone oil, with the core layer of the fiber as the inner electrode and the silver layer on the surface of the fiber as the outer electrode. The composite piezoelectric layer in the middle is subjected to corona polarization treatment. The polarization treatment voltage is 25kV, the temperature is 150℃, and the time is 6h to obtain the self-generating sensing fiber.

[0050] Step S5: The polydimethylsiloxane main agent and curing agent are blended and used as a coating material. The polarized sensing fibers are then encapsulated using a dip-coating method to obtain the desired result. Figure 1 and Figure 2 The self-generating sensing fiber shown.

[0051] Example 2

[0052] Step S1: Prepare the core spinning solution and the shell spinning solution respectively, i.e.

[0053] Weigh 100 parts of polyurethane and 1 part of silane coupling agent KH550 and add them to 800 parts of N,N-dimethylformamide and stir to dissolve. After complete dissolution, add 200 parts of liquid metal and disperse using ultrasonication at 800W for 15 minutes to disperse into micro-nano particles. The dispersion process is carried out in an ice bath at 8℃. After complete dispersion, the core layer spinning solution is obtained.

[0054] Weigh 100 parts of lead zirconate titanate and add it to 700 parts of N,N-dimethylformamide for ultrasonic dispersion. Use 800W ultrasonic dispersion for 20 minutes. The dispersion process is carried out in an ice bath at 8°C. Then, place the uniformly dispersed lead zirconate titanate suspension on a stirrer and stir rapidly. At the same time, add 100 parts of polyurethane and 100 parts of silver nitrate to the suspension and continue stirring until completely dissolved to obtain the shell spinning solution.

[0055] Step S2: The core spinning solution and the shell spinning solution are placed on a wet spinning device and extruded sequentially into a coagulation bath via a metering pump and a coaxial needle for solidification, stretching, and winding. The extrusion speeds of the core spinning solution and the shell spinning solution are 5 m / min and 3 m / min, respectively, to obtain a composite fiber with a core-sheath structure.

[0056] Step S3: The composite fiber is impregnated in a reducing agent sodium borohydride solution to allow the Ag in the silver precursor to... + Gradually migrate to the fiber surface and react fully with the reducing agent to generate nano-silver, which accumulates in large quantities on the surface to form a composite piezoelectric layer. After washing away the excess reducing agent, a multi-layer coaxial conductive fiber is obtained.

[0057] Step S4: The conductive fiber is placed in silicone oil, with the core layer of the fiber as the inner electrode and the silver layer on the surface of the fiber as the outer electrode. The composite piezoelectric layer in the middle is subjected to corona polarization treatment. The polarization treatment voltage is 23kV, the temperature is 170℃, and the time is 6h to obtain the self-generating sensing fiber.

[0058] Step S5: After the polydimethylsiloxane main agent and curing agent are blended, the mixture is used as a coating material to encapsulate the polarized sensing fiber by dip coating to obtain the self-generating sensing fiber.

[0059] Example 3

[0060] Step S1: Prepare the core spinning solution and the shell spinning solution respectively, i.e.

[0061] Weigh 100 parts of polyurethane and 1 part of silane coupling agent KH570 and add them to 800 parts of N,N-dimethylformamide and stir to dissolve. After complete dissolution, add liquid metal and disperse using 1000W ultrasonication for 15 minutes to disperse into micro-nano particles. The dispersion process is carried out in an ice bath at 0℃. After complete dispersion, the core layer spinning solution is obtained.

[0062] Weigh 150 parts of lead zirconate titanate and add it to 700 parts of N,N-dimethylformamide for ultrasonic dispersion. Use 1200W ultrasonic dispersion for 20 minutes. The dispersion process is carried out in an ice bath at 0℃. Then, place the uniformly dispersed lead zirconate titanate suspension on a stirrer and stir rapidly. At the same time, add 100 parts of polyurethane and 150 parts of silver trifluoroacetate to the suspension and continue stirring until completely dissolved to obtain the shell spinning solution.

[0063] Step S2: The core spinning solution and the shell spinning solution are placed on a wet spinning device and extruded sequentially into a coagulation bath via a metering pump and a coaxial needle for solidification, stretching, and winding. The extrusion speeds of the core spinning solution and the shell spinning solution are 5 m / min and 4 m / min, respectively, to obtain a composite fiber with a core-sheath structure.

[0064] Step S3: The composite fiber is impregnated in a reducing agent hydrazine hydrate solution to allow the Ag in the silver precursor to... + Gradually migrate to the fiber surface and react fully with the reducing agent to generate nano-silver, which accumulates in large quantities on the surface to form a composite piezoelectric layer. After washing away the excess reducing agent, a multi-layer coaxial conductive fiber is obtained.

[0065] Step S4: The conductive fiber is placed in silicone oil, with the core layer of the fiber as the inner electrode and the silver layer on the surface of the fiber as the outer electrode. The composite piezoelectric layer in the middle is subjected to corona polarization treatment. The polarization treatment voltage is 25kV, the temperature is 160℃, and the time is 8h to obtain the self-generating sensing fiber.

[0066] Step S5: After the polydimethylsiloxane main agent and curing agent are blended, the mixture is used as a coating material to encapsulate the polarized sensing fiber by dip coating to obtain the self-generating sensing fiber.

[0067] Comparative Example 1

[0068] The material composition is the same as in Example 1, except that the electrospinning + hot pressing + multilayer composite process provided by the published patent CN118756432A is used.

[0069] Comparative Example 2

[0070] The material composition is the same as in Example 1, except that the electrospinning + ZnO + multilayer composite process provided by the published patent CN113654577A is used.

[0071] Comparative Example 3

[0072] The material composition is the same as in Example 1, except that the electrospinning piezoelectric ceramic + multilayer composite process provided by the published patent CN108827502A is used.

[0073] Comparative Example 4

[0074] The material composition is the same as in Example 1, except that the three-dimensional weaving method provided by the published patent CN219568187U is used.

[0075] Comparative Example 5

[0076] The material composition is the same as in Example 1, except that the template-assisted + sol-gel method provided in the published literature "Science Advances" DOI: 10.1126 / sciadv.abf0795 is used.

[0077] Specifically, the material composition used in Comparative Examples 1-5 is the same as that in Example 1, and the performance parameters are those of the preferred examples.

[0078] Specifically, the molding methods and properties of the sensing fibers in Examples 1-3 and Comparative Examples 1-5 are shown in Table 1 below.

[0079]

[0080] Specifically, piezoelectric sensing fibers are directly prepared using coaxial wet spinning and then processed into wearable fabrics. This overcomes the problem of air impermeability in multilayer composite film structure piezoelectric sensors provided in Comparative Examples 1-4, and meets the requirements for long-term wear of sensors in practical applications.

[0081] Specifically, the coaxial spinning-co-in-situ reduction technology enables the simple and rapid molding of multi-layer coaxial piezoelectric fibers with internal and external electrode layers, making continuous production possible.

[0082] Specifically, by achieving self-generating power sensing performance of fibers through piezoelectric polarization treatment, the output of piezoelectric sensing signals is stronger and more stable, enhancing their durability in practical applications.

[0083] In summary, this multilayer coaxial piezoelectric sensing fiber and its preparation method, along with the flexible wearable fabric, directly prepares piezoelectric sensing fibers using coaxial wet spinning, overcoming the air-impermeability problem of multilayer film structure piezoelectric sensors. Simultaneously, by utilizing a fibrous liquid metal composite as the inner electrode of the core layer, and combining it with an in-situ reduction method to migrate silver ions in the composite system to form the outer electrode of the shell layer, the fiber, after polarization treatment, can be used as a self-generating sensor. The piezoelectric sensing signal output is stronger and more stable, and after being processed into flexible wearable fabric, it has a wider range of applications.

[0084] Based on the above-described preferred embodiments of the present invention, and through the foregoing description, those skilled in the art can make various changes and modifications without departing from the inventive concept. The technical scope of this invention is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. A method for preparing multilayer coaxial piezoelectric sensing fibers, characterized in that, Includes the following steps: Step S1: Prepare the core spinning solution and the shell spinning solution respectively, i.e. Weigh out polyurethane and silane coupling agent and add them to N,N-dimethylformamide and stir to dissolve. After complete dissolution, add liquid metal and disperse it into micro-nano particles by ultrasonication. The dispersion process is carried out in an ice bath. After complete dispersion, the core layer spinning solution is obtained. Lead zirconate titanate was weighed and added to N,N-dimethylformamide for ultrasonic dispersion. The dispersion process was carried out in an ice bath. Then, the dispersed lead zirconate titanate suspension was stirred, and polyurethane and silver precursor were added to the suspension. Stirring was continued until completely dissolved to obtain the shell spinning solution. Step S2: The core spinning solution and the shell spinning solution are placed on a wet spinning device and extruded into a coagulation bath for solidification, stretching, and winding in sequence through a metering pump and a coaxial needle to obtain a composite fiber with a core-sheath structure. Step S3: Impregnate the composite fiber in a reducing agent solution to allow the Ag in the silver precursor to... + Gradually migrate to the fiber surface and react fully with the reducing agent to generate nano-silver, which accumulates in large quantities on the surface to form a composite piezoelectric layer. After washing away the excess reducing agent, a multi-layer coaxial conductive fiber is obtained. Step S4: The conductive fiber is placed in silicone oil, with the core layer of the fiber as the inner electrode and the silver layer on the surface of the fiber as the outer electrode. The composite piezoelectric layer in the middle is subjected to corona polarization treatment to obtain a self-generating sensing fiber. Step S5: After the polydimethylsiloxane main agent and curing agent are blended, the mixture is used as a coating material to encapsulate the polarized sensing fiber by dip coating to obtain the self-generating sensing fiber.

2. The preparation method according to claim 1, characterized in that, In step S1, the core spinning solution is prepared... The mass ratio of liquid metal to polyurethane is (2-4):1; The mass ratio of polyurethane to N,N-dimethylformamide is 1:(5-10). The mass ratio of silane coupling agent to polyurethane is (1-2):

100.

3. The preparation method according to claim 1, characterized in that, In step S1, the shell spinning solution is prepared... The mass ratio of lead zirconate titanate to polyurethane is (0.7-1.5):1; The mass ratio of polyurethane to N,N-dimethylformamide is 1:(4-8). The mass ratio of silver precursor to polyurethane is (0.5-1.5):

1.

4. The preparation method according to claim 1, characterized in that, In step S1 The ultrasonic dispersion power for preparing the core spinning solution is 600-900W, and the duration is 10-30min; and the ambient temperature for ultrasonic dispersion is below 4℃. The ultrasonic dispersion power for preparing the shell spinning solution is 800-1100W, and the duration is 20-40min; and the ambient temperature for ultrasonic dispersion is below 4℃.

5. The preparation method according to claim 1, characterized in that, In step S1 The silane coupling agent includes any one or more combinations of amino, epoxy, thio, isocyanate, and ureosilanes; The silver precursor includes any one or more combinations of silver nitrate, silver acetate, silver trifluoroacetate, and silver citrate.

6. The preparation method according to claim 1, characterized in that, In step S2 The ratio of the extrusion speed of the core spinning solution to that of the shell spinning solution is (0.5-2):

1.

7. The preparation method according to claim 1, characterized in that, In step S3 The reducing agent includes any one or more combinations of formaldehyde, glyoxal, ethylenediamine, glucose, potassium sodium tartrate, sodium citrate, hydrazine hydrate, sodium borohydride, and ascorbic acid; and The concentration of the reducing agent is 0.05-0.3 mol / L.

8. The preparation method according to claim 1, characterized in that, In step S4 The polarization voltage is 6-15 kV / mm, the polarization temperature is 80-140℃, and the polarization time is 2-10h.

9. A multilayer coaxial piezoelectric sensing fiber prepared by the method described in any one of claims 1-8, characterized in that, include: From the inside out, the structure consists of an inner electrode, a composite piezoelectric layer, and an outer electrode; among which... The inner electrode comprises a liquid metal composite, the composite piezoelectric layer comprises a piezoelectric ceramic composite, and the outer electrode comprises silver nanoparticles.

10. A flexible wearable fabric, characterized in that, It is manufactured using the multilayer coaxial piezoelectric sensing fiber as described in claim 9; wherein The processing method includes any one or more combinations of knitting, weaving, braiding, and embroidery.

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