Multistage spiral entanglement interlocking piezoelectric sensing elastic yarn and preparation method and application thereof

Abstract

The invention discloses a multistage spiral entangled interlocking piezoelectric sensing elastic yarn which is characterized in that spandex is used as an elastic matrix yarn core, a silver-plated filament spirally wraps the spandex to serve as an electrode, and meanwhile, electrostatic spinning PVDF nanofiber and electrostatic spraying ZnO particles wrap the outer layer of the silver-plated filament to form a piezoelectric layer; the obtained yarn has a spiral structure, a core shell structure and an entanglement interlocking structure, has high elasticity and high voltage output performance, and is stable in structure.

Description

Technical Field

[0001] The present invention relates to intelligent wearable textile materials, and in particular to multi-stage spirally entangled interlocking piezoelectric sensing stretch yarns, and a preparation method and application thereof. Background Art

[0002] Wearable electronic devices are garnering significant attention amid the rapid rise of smart textiles. However, these devices are constrained by battery limitations in terms of flexibility, miniaturization, lightweighting, and integration. To address this challenge, piezoelectric sensors based on the self-powered effect have become a research focus. These sensors can convert minute body movements (such as stretching, twisting, bending, and pushing) into electrical energy, sensing the movements of various body parts in the form of electrical signals.

[0003] Membrane- or sheet-like piezoelectric sensors are often difficult to integrate into fabrics and cannot meet the basic wearability requirements of fabrics, such as elasticity, deformation, and breathability, limiting their application in smart wearable textiles. One-dimensional yarns are the basic units that make up fabrics and typically have high mechanical strength and flexibility. They can withstand various types of mechanical bending, twisting, and stretching. Elastic yarns can also be attached to various irregular surfaces and produce large deformations with body movement. Yarn-like piezoelectric sensors can also be integrated through weaving technology. Therefore, it is of great significance to develop elastic and weavable piezoelectric sensing yarns to provide a flexible power source for smart wearable textiles.

[0004] Chinese patent application 202211372876X discloses a flexible piezoelectric fiber comprising a metal-plated yarn, a nano-piezoelectric fiber layer, and a conductive layer. The nano-piezoelectric fiber layer covers the metal-plated yarn to form a core-spun yarn structure, and the conductive layer covers the core-spun yarn structure. Specifically, PVDF-based piezoelectric polymer powder is dissolved in a solvent mixture of DMF and acetone, and inorganic nanoparticles are added to obtain a polymer solution. The polymer solution is electrospun to form a nano-piezoelectric fiber layer that covers the surface of the metal-plated yarn to obtain a core-spun yarn structure. The conductive layer is then coated on the outer layer of the core-spun yarn structure to obtain a flexible piezoelectric fiber. This flexible piezoelectric fiber has good conformability to irregularly shaped surfaces and stable piezoelectric activity, but it has weak power generation performance and poor elasticity.

[0005] As mentioned above, the development of piezoelectric sensing yarns with elasticity, weavability, high piezoelectricity and structural stability has become an urgent problem to be solved. Summary of the Invention

[0006] In order to solve the above problems, the inventors conducted intensive research and used spandex as an elastic matrix, spirally wrapped silver-plated filaments on the outside of the spandex as electrodes, and simultaneously electrospun PVDF nanofibers and electrostatically sprayed ZnO particles were coated on the outer layer of the silver-plated filaments to form a piezoelectric layer. The resulting yarn has a spiral structure, a core-shell structure, and an entangled interlocking structure, has high elasticity and high-voltage electrical output performance, and is structurally stable, thus completing the present invention.

[0007] The object of the present invention is to provide a multi-stage spirally entangled interlocking piezoelectric sensing stretch yarn, comprising a spandex yarn core, the outer spiral of the yarn core being coated with silver-plated filaments, the outer surface of the silver-plated filaments being electrostatically spun to form PVDF nanofibers, and ZnO nanoparticles loaded therein being formed by electrostatic spraying between the PVDF nanofibers. The yarn has a spiral structure, a core-shell structure and an entangled interlocking structure.

[0008] Another object of the present invention is to provide a method for preparing a multi-stage spirally entangled interlocking piezoelectric sensing stretch yarn, comprising the following steps:

[0009] (1) Pre-stretching the spandex and fixing it on a yarn winding machine;

[0010] (2) When the spandex is rotated along the axial direction, the silver-plated filament is wrapped around the spandex to obtain an elastic electrode with a spirally wrapped structure;

[0011] (3) preparing nano zinc oxide aqueous dispersion;

[0012] (4) dissolving PVDF powder in acetone and N,N-dimethylformamide solvent to obtain PVDF electrospinning solution;

[0013] (5) using the spandex / silver-plated filament elastic electrode obtained in step (2) as a receiving substrate, rotating it axially while maintaining the pre-stretching force, and electrospinning with the PVDF electrospinning solution of step (4), while electrospinning with the nano zinc oxide aqueous dispersion of step (3), with the needles between the electrospinning and electrospinning being connected by a copper wire; and

[0014] Optional (6) remove the yarn, remove the pre-stretching force, and let it air dry.

[0015] The present invention has the following beneficial effects:

[0016] (1) The present invention pre-stretches the elastic spandex and winds a silver-plated filament thereon to form an electrode with high elasticity and a tight spiral winding structure; under the high-speed rotation of the electrode, the electrospun PVDF nanofiber is tightly wrapped around the outer layer of the electrode. When the pre-stretching force is removed, the entire yarn will retract, and under the influence of the spiral winding structure of the silver-plated filament, the PVDF nanofiber will also produce a spiral winding structure. Therefore, the entire piezoelectric yarn prepared has a multi-level spiral structure, which gives it excellent elasticity;

[0017] (2) The present invention adopts a method of simultaneously performing electrostatic spraying and electrostatic spinning to load ZnO nanoparticles with piezoelectric properties into the PVDF nanofiber layer, which can improve the power generation of the piezoelectric layer and solve the problem of easy shedding and delamination of micro-nanoparticles during use. The obtained yarn has a tangled interlocking structure, which gives it good structural stability.

[0018] (3) The present invention simultaneously uses electrospinning and electrostatic spraying to prepare the piezoelectric layer. During the electrospinning process, the high-voltage electric field exerts a stretching and polarizing effect on the PVDF nanofibers, promoting the formation of their β phase, thereby avoiding the need for additional stretching or polarization processing. The ZnO nanopiezoelectric particles are evenly distributed in the piezoelectric layer by electrostatic spraying. The synergistic piezoelectric effect of the PVDF nanofibers and the ZnO nanopiezoelectric particles gives the entire yarn excellent piezoelectric properties.

[0019] (4) Electrostatic spraying requires the use of an electrostatic field to evenly spray the micro-nanoparticle dispersion. In the present invention, the electrostatic spinning needle is connected to a high-voltage power supply, and the electrostatic spinning needle and the electrostatic spray needle are connected with a copper wire, which is equivalent to applying the same voltage to the electrostatic spray, so that the electrostatic spray can proceed smoothly, with the characteristics of convenience, speed, uniform spraying and large spray volume. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 Shown is a preparation method of a multi-stage spirally entangled interlocking piezoelectric sensing stretch yarn and a schematic diagram of the structure of the multi-stage spirally entangled interlocking piezoelectric sensing stretch yarn;

[0021] Figure 2 A scanning electron microscope photograph of the multi-stage spirally entangled interlocking piezoelectric sensing stretch yarn prepared in Example 1 is shown;

[0022] Figure 3 A scanning electron microscope image of PVDF nanofibers in the multi-stage spirally entangled interlocking piezoelectric sensing stretch yarn prepared in Example 1 is shown;

[0023] Figure 4 The diameter distribution of PVDF nanofibers in the multi-stage spirally entangled interlocking piezoelectric sensing stretch yarn prepared in Example 1 is shown;

[0024] Figure 5 The XRD spectra of the raw material PVDF powder and the PVDF nanofibers in the multi-stage spirally entangled interlocking piezoelectric sensing stretch yarn prepared in Example 1 are shown;

[0025] Figure 6 The figure shows the Fourier transform infrared spectra (FTIR) of the raw material PVDF powder and the PVDF nanofibers in the multi-stage spiral entangled interlocking piezoelectric sensing stretch yarn prepared in Example 1;

[0026] Figure 7 The tensile curve of the multi-stage spirally entangled interlocking piezoelectric sensing stretch yarn prepared in Example 1 is shown;

[0027] Figure 8 The open circuit voltage of the spandex / silver-plated filament / PVDF nanofiber / ZnO nanoparticle multi-stage spirally entangled interlocked piezoelectric sensing stretch yarn prepared in Example 1 is shown, where (a) is the output voltage of the 45 mm long yarn, and (b) is the output voltage of the 90 mm long yarn;

[0028] Figure 9 The open circuit voltage of the spandex / silver-plated filament / PVDF nanofiber multi-stage spiral entangled interlocked piezoelectric sensing stretch yarn prepared in Comparative Example 1 is shown, wherein the yarn length is 45 mm;

[0029] Figure 10 The following illustrates an example of applying the multi-stage spirally entangled interlocking piezoelectric sensing stretch yarn prepared in Example 1 to human motion monitoring.

[0030] Figure 11 Shown are the longitudinal SEM photograph (a) of the yarn obtained when the PVDF electrospinning solution concentration is 8% and the longitudinal photograph (b) of the PVDF nanofiber;

[0031] Figure 12 Shown are the longitudinal SEM photos (a) of the yarn obtained when the PVDF electrospinning solution concentration is 10% and the longitudinal photos (b) of the PVDF nanofibers;

[0032] Figure 13 Shown are the longitudinal SEM photograph (a) of the yarn obtained when the PVDF electrospinning solution concentration is 14% and the longitudinal photograph (b) of the PVDF nanofiber;

[0033] Figure 14 Shown are the longitudinal SEM photograph (a) of the yarn obtained when the PVDF electrospinning solution concentration is 16% and the longitudinal photograph (b) of the PVDF nanofibers 14% and 16% in Example 3;

[0034] Figure 15Shown are the longitudinal SEM photograph (a) of the yarn obtained when the spinning voltage is 11 kV and the longitudinal photograph (b) of the PVDF nanofiber in Example 4;

[0035] Figure 16 Shown are the longitudinal SEM photograph (a) of the yarn obtained when the spinning voltage is 13 kV and the longitudinal photograph (b) of the PVDF nanofiber;

[0036] Figure 17 Shown are the longitudinal SEM photograph (a) of the yarn obtained when the spinning voltage is 17 kV and the longitudinal photograph (b) of the PVDF nanofiber in Example 4;

[0037] Figure 18 Shown are the longitudinal SEM photograph (a) of the yarn obtained when the spinning voltage is 19 kV and the longitudinal photograph (b) of the PVDF nanofiber;

[0038] Figure 19 The longitudinal SEM photograph (a) of the yarn obtained when the receiving distance is 6 cm and the longitudinal photograph (b) of the PVDF nanofiber are shown;

[0039] Figure 20 Shown are the longitudinal SEM photograph (a) of the yarn obtained when the receiving distance is 8 cm and the longitudinal photograph (b) of the PVDF nanofiber;

[0040] Figure 21 The longitudinal SEM photograph (a) of the yarn obtained when the receiving distance is 12 cm and the longitudinal photograph (b) of the PVDF nanofiber are shown;

[0041] Figure 22 The longitudinal SEM photograph (a) of the yarn obtained when the receiving distance is 14 cm and the longitudinal photograph (b) of the PVDF nanofiber are shown;

[0042] Figure 23 Photos showing the distribution of ZnO nanoparticles obtained in Example 6, wherein (a) is when the ZnO dispersion concentration is 5%, (b) is when the ZnO dispersion concentration is 10%, and (c) is when the ZnO dispersion concentration is 15%; DETAILED DESCRIPTION

[0043] The present invention will be described in further detail below with reference to the accompanying drawings and examples, through which the features and advantages of the present invention will become more clearly understood.

[0044] In the present invention, the multi-stage spirally entangled interlocking piezoelectric sensing stretch yarn has a spiral structure, such as Figure 2 As shown in (a), it is formed by silver-plated filaments and PVDF nanofibers wrapped around the yarn core in a spiral shape.

[0045] The multi-stage spirally entangled interlocking piezoelectric sensing stretch yarn has a core-shell structure, such as Figure 2 As shown in (b), the yarn includes a spandex yarn core, a silver-plated filament layer, a PVDF nanofiber layer, and a zinc oxide nanoparticle layer from the inside to the outside, thus forming a multi-level core-shell structure.

[0046] The multi-stage spiral entangled interlocking piezoelectric sensing stretch yarn has an entangled interlocking structure, such as Figure 2 As shown, the silver-plated filaments in the yarn and the PVDF nanofibers and zinc oxide nanoparticle layers coated thereon, as well as the PVDF nanofibers and zinc oxide nanoparticles, are entangled and locked with each other, especially the PVDF nanofibers and zinc oxide nanoparticles are entangled and locked with each other, forming a stable and high-performance piezoelectric layer.

[0047] The multi-stage spirally entangled interlocking piezoelectric sensing stretch yarn has a spirally wrapped core-shell structure with elastic spandex as the core. First, the silver-plated filament is spirally wrapped around the outer layer of spandex, and secondly, the PVDF nanofiber is spirally wrapped around the outer layer of the silver-plated filament. When the yarn is stretched by external force, the tightly wound spiral structure can give the yarn excellent elasticity like a spring.

[0048] The piezoelectric layer of the multi-stage spirally entangled interlocking piezoelectric sensing stretch yarn of the present invention is composed of PVDF nanofibers and ZnO piezoelectric particles. The synergistic effect of the two piezoelectric materials enables the yarn to have high piezoelectric performance and high piezoelectric output voltage.

[0049] During electrospinning, the high-voltage electric field exerts a tensile and polarizing effect on the fiber, which can promote the formation of the β phase in PVDF, avoiding the need for additional tensile or polarization processing. Increasing the content of the β crystal can effectively enhance the piezoelectric effect of PVDF.

[0050] In this method, ZnO nanoparticles are evenly loaded between PVDF nanofibers through electrostatic spraying to enhance piezoelectric performance. Compared to directly adding zinc oxide particles to the PVDF spinning solution, this method overcomes the problem of limited addition and the impact on fiber formation, and achieves higher piezoelectric performance. Compared to surface coating methods that physically adsorb or coat functional micro-nanoparticles onto the fiber surface, this method solves the problem of micro-nanoparticles easily falling off and delaminating during use.

[0051] In a preferred embodiment, in step (1), the pre-stretching rate of the spandex is 50-150%, more preferably about 100%.

[0052] The spandex used in the present invention is preferably spandex filaments, and the spandex filaments are 1120D.

[0053] In a preferred embodiment, in step (2), the silver-plated filament is nylon silver-plated filament, that is, silver is plated on nylon, such as nylon silver-plated filaments of various specifications such as 40D, 75D, and 100D.

[0054] For the silver-plated filament used in the present invention, the diameter is preferably 75D.

[0055] In step (3) of the present invention, as for the nano zinc oxide, zinc oxide particles with a particle size of nanometer level can be used, and there is no particular limitation on this.

[0056] In a preferred embodiment, in step (3), the concentration of the obtained nano zinc oxide aqueous dispersion is 10%.

[0057] In a preferred embodiment, in step (4), the solvent is selected from acetone and N,N-dimethylformamide, and the concentration of the PVDF electrospinning solution is 12%.

[0058] In a preferred embodiment, in step (5), the spinning voltage is 15 kV and the receiving distance is 10 cm.

[0059] In a preferred embodiment, in step (5), the needles between the electrostatic spraying and the electrostatic spinning are connected by copper wire.

[0060] Example 1

[0061] (1) The spacing of the yarn winding machine is adjusted to 20 cm, and the two ends of the 10 cm long spandex are fixed on the yarn winding machine. At this time, the pre-stretching rate of the spandex is 100%;

[0062] (2) Cut a 75 cm silver-plated filament (nylon silver-plated filament, 75D), fix one end of it to one end of the spandex, and start the yarn winding machine at a speed of 200 r / min to evenly wrap the silver-plated filament around the spandex to prepare an elastic electrode with a spirally wrapped structure;

[0063] (3) Take 3 g of 20% nano zinc oxide aqueous dispersion (ZnO diameter is less than or equal to 50 nm), add 3 g of deionized water to dilute to a concentration of 10%, and ultrasonicate for 30 minutes;

[0064] (4) 1 g of PVDF powder was placed in a conical flask, 1.48 g of acetone and 5.84 g of N,N-dimethylformamide were added, and the flask was sealed. The mixture was stirred on a magnetic stirrer for 10 h to obtain a PVDF electrospinning solution with a concentration of 12%;

[0065] (5) Using the silver-plated filament / spandex yarn obtained in step (2) as a receiving matrix, 4.0 ml of the spinning solution in step (4) was extracted for electrospinning, the spinning voltage was controlled to be 15 kV, the receiving distance was 10 cm, and the spinning speed was 0.5 mL / h; at the same time, 4.0 ml of the zinc oxide dispersion in step (3) was extracted for electrostatic spraying, and the needles between the electrostatic spraying and the electrostatic spinning were connected by a copper wire; electrospinning and electrostatic spraying were carried out simultaneously for 2 hours;

[0066] (6) The yarn is removed from the receiving device, the pre-stretching force is removed, and the yarn is left to air-dry at room temperature for 12 hours to obtain a multi-stage spirally entangled interlocking piezoelectric sensing stretch yarn.

[0067] The morphology of the piezoelectric sensing yarn is as follows Figure 2 As shown. Figure 2 (a) It can be seen that the prepared yarn has a uniform spiral winding structure in the longitudinal direction; Figure 2 (c) shows PVDF nanofibers and ZnO nanoparticles. Since electrostatic spraying and electrospinning are carried out simultaneously, most of the ZnO nanoparticles are loaded inside the PVDF fiber layer, and only a small amount of nanoparticles are on the surface of the PVDF fiber. Figure 2 (b) shows a cross section of the yarn, showing its multi-layer core-shell structure.

[0068] The morphology of PVDF nanofibers is as follows Figure 3 As shown, the diameter distribution is Figure 4 As shown in the figure, the nanofibers are straight and smooth, evenly distributed, and have a diameter of about 600 nm.

[0069] from Figure 5 The XRD curve of the PVDF powder shows three strong diffraction peaks at 2θ of 19°, 20.6°, and 27.3°, corresponding to the (020), (110), and (021) crystal planes of α-phase PVDF, respectively. This indicates that most of the crystalline forms in the PVDF polymer exist in the α-phase. When PVDF is electrospun into nanofibers, the α-phase crystallization peak almost disappears. A strong diffraction peak appears at 21.9° in the XRD curve of the PVDF nanofibers, which is the β-phase crystallization peak. This indicates that the electrospinning process can significantly promote the generation of the β-phase.

[0070] The FTIR spectrum of the yarn is as follows Figure 6 As shown. It can be seen that PVDF powder has a -1 、796cm -1 , 976cm -1 、1065cm -1 There is an obvious α-phase characteristic peak at 838 cm -1 、1275cm -1There are two obvious β-phase crystallization peaks, which further proves the transformation of α-phase to β-phase in electrospun PVDF nanofibers, indicating that the electrospinning process promotes the generation of β-phase.

[0071] The tensile curve of the yarn is as follows Figure 7 As shown in the figure, it can be seen that its elongation at break is close to 500%, indicating that it has high elasticity.

[0072] Figure 8 The output voltage of the yarn at 1N and 0.5Hz is 1.8V when the yarn length is 45mm. As the yarn length increases, the output voltage also increases. When the yarn length is 90mm, the output voltage reaches 15V, showing high power generation performance.

[0073] Example 2

[0074] The piezoelectric sensing yarn prepared in Example 1 was applied to force-to-electricity conversion and motion monitoring. When the wearer exercises, the yarn is subjected to pressure or tension, which converts the force into an electrical signal for monitoring physiological indicators such as heart rate and movement amplitude. The results are as follows: Figure 10 shown.

[0075] Example 3

[0076] The multi-stage spirally entangled interlocking piezoelectric sensing stretch yarn was prepared in the same manner as in Example 1, except that the concentrations of the PVDF electrospinning solution were different, namely 8%, 10%, 14% and 16%, respectively.

[0077] The longitudinal SEM images of the yarn and the longitudinal images of the PVDF nanofibers are shown in Figure 11 、 Figure 12 、 Figure 13 and Figure 14 middle.

[0078] turn out:

[0079] (1) When the PVDF concentration is 8%, the PVDF fibers are coated on the outer layer of the silver-plated filaments, but the fibers are adhered, agglomerated, and messy, and the yarn does not form an obvious spiral wrapping structure. This may be because the spinning solution concentration is too low and the fibers cannot be well formed;

[0080] (2) When the PVDF spinning solution concentration was increased to 10%, the morphology of the PVDF fiber improved, but no obvious spiral wrapping structure was formed;

[0081] (3) When the PVDF spinning solution concentration increases to 12%, the PVDF fiber morphology is better, the diameter distribution is more uniform, there is no adhesion and beading phenomenon, and a very uniform and regular spiral interlocking structure is formed;

[0082] (4) When the PVDF concentration was further increased to 14%, very few PVDF fibers were spun. When the concentration was 16%, almost no PVDF fibers were spun. This may be because the spinning solution was too viscous and the electrostatic field force was not enough to stretch the fibers.

[0083] Example 4

[0084] The multi-stage spirally entangled interlocking piezoelectric sensing stretch yarn was prepared in the same manner as in Example 1, with the only difference being the spinning voltages of 11 kV, 13 kV, 17 kV, and 19 kV, respectively.

[0085] The longitudinal SEM images of the yarn and the longitudinal images of the PVDF nanofibers are shown in Figure 15 、 Figure 16 、 Figure 17 and Figure 18 middle.

[0086] turn out:

[0087] (1) When the spinning voltage is 11 kV, the electrostatic field between the spinneret and the receiving device is weak due to the low spinning voltage, and there is insufficient tensile force. Therefore, the PVDF spinning solution does not form fibers, and only a small amount of droplets are sprayed outside the silver-plated filaments.

[0088] (2) As the voltage increases to 13 kV, PVDF nanofibers gradually form and fibers with good morphology can be continuously spun, but no spiral wrapping structure is formed;

[0089] (3) When the voltage is increased to 15 kV, spinning is smooth and the filaments are continuous, there is no beading or adhesion between the fibers, the fiber morphology is good, and a uniform spirally wrapped interlocking structure is formed;

[0090] (4) When the spinning voltage was further increased to 17 kV and 19 kV, the spinning became intermittent and the fibers showed severe adhesion. This may be because, on the one hand, increasing the voltage would increase the force to overcome the inward contraction of the droplet surface, resulting in an unstable spinning process. On the other hand, the larger spinning voltage led to an electrostatic field strength, and the Taylor cone was subjected to excessive tension, causing the fiber to break during the stretching process, and even a large amount of spinning liquid was directly ejected.

[0091] Example 5

[0092] The multi-stage spirally entangled interlocking piezoelectric sensing stretch yarn was prepared in the same manner as in Example 1, with the only difference being that the receiving distances were different, namely 6 cm, 8 cm, 12 cm and 14 cm.

[0093] The longitudinal SEM images of the yarn and the longitudinal images of the PVDF nanofibers are shown in Figure 19 、 Figure 20 、 Figure 21 and Figure 22 middle.

[0094] turn out:

[0095] (1) When the receiving distance is small, the PVDF fibers not only have adhesion but also have a large area of ​​non-fibrous stacking. This may be because the short distance does not provide sufficient time for the polymer droplets to be stretched from the needle to the receiving device. More PVDF spinning solution is not fully stretched or is directly sprayed onto the receiving device in the form of droplets.

[0096] (2) Increasing the receiving distance to 10 cm provides sufficient time for the polymer droplet to be stretched from the needle to the receiving device. On the one hand, the Taylor cone can be fully stretched into fibers. On the other hand, more solvent can be evaporated, reducing the residual solvent on the fiber surface. As a result, the fibers are straight, smooth, and evenly distributed, and are tightly wrapped in the outer layer of the silver-plated filament, forming a regular spiral wrapping structure in the natural state.

[0097] (2) When the receiving distance continues to increase to 12 cm and 14 cm, it can be found that the adhesion between fibers gradually increases, and a regular spirally wrapped interlocking structure cannot be formed. This may be because when the applied voltage remains unchanged, the electric field strength decreases with the increase of the receiving distance, resulting in some fibers not being fully stretched and sticking to each other.

[0098] Example 6

[0099] Zinc oxide electrostatic spraying was performed in the same manner as in Example 1, wherein the concentrations of the ZnO dispersion were 5% and 15%, respectively.

[0100] The distribution of nanoparticles in the obtained zinc oxide dispersion is as follows: Figure 23 shown.

[0101] turn out:

[0102] (1) When the concentration of ZnO dispersion is 5% and 10%, the distribution of ZnO nanoparticles sprayed by electrostatic spraying is relatively uniform;

[0103] (2) When the concentration of the ZnO dispersion is 15%, the high concentration causes the spray needle to be clogged, so very few nanoparticles are sprayed out.

[0104] Comparative Example 1

[0105] The multi-stage spirally entangled interlocking piezoelectric sensing stretch yarn was prepared in the same manner as in Example 1, except that only electrospinning was performed without electrostatic spraying of the zinc oxide dispersion.

[0106] The open circuit voltage of the obtained yarn (45 mm) is as follows Figure 9 As shown, the maximum value is 0.9V.

[0107] The maximum output voltage of the yarn (45 mm) in Example 1 is 1.8 V, which is twice that of the yarn in Comparative Example 1, indicating that the piezoelectric properties of the yarn are significantly improved by applying ZnO piezoelectric nanoparticles loaded in the spirally wrapped PVDF fiber by the electrostatic spraying method.

[0108] The present invention has been described in detail above with reference to specific embodiments and / or exemplary examples and the accompanying drawings. However, these descriptions should not be construed as limiting the present invention. Those skilled in the art will appreciate that various equivalent substitutions, modifications, or improvements may be made to the technical solutions and implementations of the present invention without departing from the spirit and scope of the present invention, all of which fall within the scope of the present invention. The scope of protection of the present invention shall be determined by the appended claims.

Claims

1. A multi-stage spirally entangled interlocking piezoelectric sensing stretch yarn comprising a spandex yarn core, an outer spiral of the yarn core being coated with silver-plated filaments, an outer spiral of the silver-plated filaments being coated with PVDF nanofibers formed by electrostatic spinning, and ZnO nanoparticles formed therein by electrostatic spraying being loaded between the PVDF nanofibers.

2. The multi-stage spirally entangled interlocking piezoelectric sensing stretch yarn according to claim 1, wherein the yarn has a spiral structure, a core-shell structure and an entangled interlocking structure.

3. The multi-stage spirally entangled interlocking piezoelectric sensing stretch yarn according to claim 1, wherein: The spandex yarn core has pre-tensile stress when coated with PVDF nanofiber.

4. A method for preparing a multi-stage spirally entangled interlocking piezoelectric sensing stretch yarn, comprising the following steps: (1) Pre-stretching the spandex and fixing it on a yarn winding machine; (2) When the spandex is rotated along the axial direction, the silver-plated filament is wrapped around the spandex to obtain an elastic electrode with a spirally wrapped structure; (3) preparing nano zinc oxide aqueous dispersion; (4) dissolving PVDF powder in a solvent to obtain a PVDF electrospinning solution; (5) using the spandex / silver-plated filament elastic electrode obtained in step (2) as a receiving substrate, rotating it axially while maintaining the pre-stretching force, and electrospinning with the PVDF electrospinning solution of step (4), while electrospinning with the nano zinc oxide aqueous dispersion of step (3), with the needles between the electrospinning and electrospinning being connected by a copper wire; and Optional (6) remove the yarn, remove the pre-stretching force, and let it air dry.

5. The method according to claim 4, wherein: In step (1), the pre-stretching rate of the spandex is 50-150%.

6. The method of claim 4, wherein: In step (2), the silver-plated filament is nylon silver-plated filament.

7. The method of claim 4, wherein: In step (3), the concentration of the nano zinc oxide aqueous dispersion is 10%.

8. The method of claim 4, wherein: In step (4), the solvent is selected from acetone and N,N-dimethylformamide, The concentration of PVDF electrospinning solution was 12%.

9. The method of claim 4, wherein: In step (5), the spinning voltage is 15 kV and the receiving distance is 10 cm.

10. The method of claim 4, wherein: In step (6), the mixture is allowed to stand at room temperature.

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