KR101816841B1 - A piezoelectric fiber, a preparation method thereof, and textile, clothing and a wearable piezoelectric sensor using the fiber - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a piezoelectric fiber yarn, a method of manufacturing the same, and a fabric, an apparel product, and a coated piezoelectric sensor using the same. More particularly, A piezoelectric material layer coated on a surface of the core conductive fiber yarn; And a conductive polymer layer coated on the surface of the piezoelectric material layer, whereby the fiber material itself can be used for signal detection without attaching electrodes, a method of manufacturing the same, and a fabric, an apparel product, Sensor.

Description

TECHNICAL FIELD The present invention relates to a piezoelectric fiber yarn, a method of manufacturing the same, and a fabric, an apparel product, and a coated piezoelectric sensor using the same,

The present invention relates to a piezoelectric fiber yarn, a method of manufacturing the same, and a fabric, an apparel product, and a coated piezoelectric sensor using the same.

The term "piezoelectricity" refers to the phenomenon of causing dielectric polarization by applying mechanical strain. The first piezoelectric effect is also referred to as a reverse piezoelectric effect, or a phenomenon in which an electric field is applied to cause distortion, is called a second piezoelectric effect. The latter is electrical distortion, but the inverse piezoelectric effect is a linear function of electric field E, sometimes distinguishing it from pure electrical distortion proportional to E².

The principle of the piezoelectric is divided into ferroelectric due to the crystal structure and a case where the symmetry of the crystal structure is lost. First, the ferroelectric principle due to the crystal structure is as follows. There is also a ferroelectric material in the electric property, just as there is a ferromagnetic material in relation to the magnetic properties of the material. This is a property that polarization is applied when a strong external electric field is applied and polarization is maintained even if an external electric field is removed. That is, it maintains its polarized state because of the specificity of the crystal structure. The ferroelectric material is also a piezoelectric material. This is because the electrical polarity changes when the shape of the material changes due to mechanical pressure. For example, when compressed, the number of molecules having a dipole moment per unit volume is increased, so that the polarity increases. Next, when the symmetry of the crystal structure disappears, the principle is as follows. Quartz (SiO ₂ ), a piezoelectric material that exists naturally, is a case in which there is a ferroelectric substance that is polarized when a pressure is applied even if it is not a ferroelectric substance. The crystal structure in the normal state is symmetrical and electrically neutral, but when pressure is applied, the shape of the crystal structure changes and dipole moments are generated and thus polarized.

On the other hand, smart wear is a new concept of futuristic garment that combines new technologies and breaks the concept of traditional clothes. SmartWare is a futuristic garment that is out of the traditional textile and garment concept by combining new technology such as information technology (IT), biotechnology (BT), micro nano scale production technology and environment friendly material (ET). New concepts such as semiconductor chips, sensors, and digital devices have been introduced, such as miniaturization and ultra-light weight, which combine the functionality of textile materials that react to external stimuli and self-reactions, and the mechanical functions of garments and fabrics themselves. Wearable computers, digital garments, and the like.

Depending on the component, it is divided into inactive smartware, responsive smartware, and intelligent smartware. Inactive SmartWare is smartware with the ability to detect information about the wearer environment and acts only as a detector. The responsive smartware is smartware that senses stimuli from the external environment and reacts to stimuli, and acts as both a detector and an actuator. Intelligent SmartWare is smartwares that play a role by selecting appropriate behaviors according to a given situation.

Depending on the functional characteristics, it is divided into early stage and late stage. The initial stage of smartware is inactive smartware with embedded electronic elements such as sensors for monitoring vital signs, micro MP3, and GPS (Global Positioning System). Late stage smartware refers to intelligent smartware that can sense stimuli from clothing environment and external environment, process information, and act appropriately.

Smartwares, first developed for military purposes in the United States in the mid-1990s, have been used for a variety of purposes, including sportswear, hospital uniforms, sudden infant suits, uniforms, fire fighting suits, work clothes and space suits. Currently, active research is being conducted not only in the United States but also in Europe and Japan. Smartwares consist of convergence technologies in each field rather than original technology development.

Conventionally, techniques for applying smart materials using a piezoelectric material include a piezoelectric sensing unit including a piezoelectric polyvinylidene fluoride (PVDF) film and electrodes formed on both sides of the film, Although smartware development has been attempted, such smartwares have a limitation in applying to actual clothing products, such as the need to form separate electrodes on both sides of PVDF film, This results in inconvenience due to lack of flexibility. Therefore, it is required to develop a piezoelectric wearable product that is more comfortable to wear and easy to apply.

Under these circumstances, the inventors of the present invention have found that when a fiber yarn used for weaving clothes is made into a conductive fiber yarn and formed into a core fiber yarn and a piezoelectric layer and a conductive polymer layer are sequentially formed thereon, It is possible to detect an electric signal due to pressure, and the present invention has been completed.

Accordingly, an object of the present invention is to provide a piezoelectric fiber yarn which can be used for signal detection without attaching an electrode, and a method for producing the same.

Another object of the present invention is to provide a piezoelectric fabric woven with the piezoelectric fiber yarn, a piezoelectric garment product manufactured using the piezoelectric fabric, and a coated piezoelectric sensor fabricated using the piezoelectric fiber yarn.

A first aspect of the present invention relates to a core-conductive fiber yarn; A piezoelectric layer formed on a surface of the core conductive fiber yarn; And a conductive polymer layer formed on a surface of the piezoelectric layer.

A second aspect of the present invention is a method for manufacturing a core conductive fiber yarn, comprising the steps of: (1) forming a piezoelectric layer on a surface of a core conductive fiber yarn; And a step of forming a conductive polymer layer on the surface of the piezoelectric layer (step 2).

A third aspect of the present invention provides a piezoelectric fabric woven with the piezoelectric fiber yarn.

A fourth aspect of the present invention provides a piezoelectric garment product made using the piezoelectric fabric.

A fifth aspect of the present invention provides a coated piezoelectric sensor manufactured using the piezoelectric fiber yarn.

Hereinafter, the present invention will be described in detail.

Conventionally, a technique of applying a piezoelectric material to smartware includes attaching a piezoelectric film to two electrodes of a film and then attaching the piezoelectric film to clothes to detect EMG, ECG, respiration conduction, and thigh muscle movement signals. However, A separate electrode is required for detection of wear and tear of the wearable device.

The present invention provides a conductive fiber yarn in the form of a fiber yarn for use in weaving clothes and forming the conductive fiber yarn as a core fiber yarn to thereby form a piezoelectric layer and a conductive polymer layer, It can be applied for detecting electric signals. In addition, by using piezo-electric fiber yarn itself, it is more flexible than film-type sensor, and it is possible to manufacture wearable device integrated with fiber by making it fit to wearable device. Accordingly, by using the piezoelectric fiber yarn according to the present invention, it is possible to provide a clothes product and a coated piezoelectric sensor having excellent activity.

The piezoelectric fiber yarn of the present invention comprises a core conductive fiber yarn; A piezoelectric layer formed on a surface of the core conductive fiber yarn; And a conductive polymer layer formed on the surface of the piezoelectric layer.

The structure of the piezoelectric fiber yarn according to one embodiment of the present invention using PVDF as the material of the piezoelectric layer is as shown in Fig. In FIG. 1, an electric signal due to the piezoelectric phenomenon occurring in the piezoelectric layer formed of PVDF can be easily detected by using the inner core conductive fiber yarn and the outer conductive polymer layer as electrodes.

The term "core conductive fiber yarn" used in the present invention means to form a core portion of the piezoelectric fiber yarn of the present invention as an actual structure having electrical conductivity. The core conductive fiber yarn may preferably have a resistance per 1 cm of short fibers of 10 ¹² Ω or less, more preferably 10 ¹² Ω to 10 ¹⁵ Ω per 1 cm of short fibers.

In the present invention, the diameter of the core conductive fiber yarn may preferably be 8 [mu] m to 50 [mu] m.

In the present invention, the core conductive fiber yarn has flexibility and is advantageous for application to a wearable device due to the ease of weaving.

In the present invention, the core conductive fiber yarn may have a conductive layer formed on the surface or inside of the fiber yarn. That is, the core conductive fiber yarn may have a conductive layer formed on the surface of the fiber yarn or a conductive layer formed inside the fiber yarn. In addition, the core conductive fiber yarn may be one in which conductive particles are dispersed in a fiber yarn.

In the present invention, the fiber yarn may be made of a synthetic polymer, a natural polymer, or a mixed polymer thereof, and the conductive layer or the conductive particles may be carbon or metal. Specifically, a carbon material such as carbon nanotubes or a metal selected from the group consisting of Ag, Au, Pt, Cu, Ti, Al, V, Cr, Mn, Fe, Co and Ni.

In one embodiment, the core conductive fiber yarn may be formed by forming a conductive layer by coating a conductive material on the surface of a synthetic fiber or a fiber material made of a natural polymer. The conductive layer may be formed as a single layer or may be laminated with different kinds of conductive layers. In another embodiment, the core conductive fiber yarns may be formed from a resin composition in which conductive particles are evenly dispersed in the synthetic polymer. Specifically, in one embodiment of the present invention, the conductive fiber yarn was obtained from CK International (Canada).

The term "piezoelectric layer" used in the present invention means a layer exhibiting piezoelectric characteristics. The piezoelectric layer may be made of a single crystal, a polycrystalline ceramic, a polymeric material, a thin film material, or a composite material obtained by compounding a polycrystalline material and a polymeric material.

Specifically, as the single crystal piezoelectric material, α-AlPO ₄ , α-SiO ₂ , LiTaO ₃ , LiNbO ₃ , Pb ₅ -Ge ₃ O ₁₁ , Tb ₂ (MoO ₄ ) ₃ , Li ₂ B ₄ O ₇ , CdS, ZnO _{, Bi 12 SiO 20, Bi 12} GeO 20, PZN-PT [Pb (Zn 2/3 Nb 1/3) O 3 -PbTiO 3], PMN-PT [Pb (Mg 2/3 Nb 1/3) O 3 -PbTiO ₃ ], triglycine sulfate (TGS), and the like. Examples of the polycrystalline piezoelectric material include lead zirconate titanate, PbZrO ₃ -PbTiO ₃ , PT (PbTiO ₃ ), PZT- (PZT-Complex Perovskite) system, and BaTiO ₃ . Examples of the thin film piezoelectric material include ZnO, CdS, and AlN. Examples of the piezoelectric material include polyvinylidene fluoride (PVDF), poly (vinylidene fluoride-co-trifluroethylene [ poly (vinylidene fluoride-co-tetrafluoroethylene), P (VDF-TeFE)], and the like, Examples of the composite piezoelectric material include PZT-PVDF, PZT-silicone rubber (PZT-silicone rubber), PZT-epoxy (PZT-Epoxy), and PZT-foamed urethane. These materials may be used alone or as a mixture thereof.

The quartz crystal (α-SiO ₂ ) widely used as a single crystal piezoelectric material is used as an oscillator element that generates a signal frequency because the bandwidth of the resonant frequency is narrow and the temperature coefficient is very small. It is disadvantageous in that the price is high and the electromechanical coupling coefficient is small Which limits the application area. LiNbO ₃ and LiTaO ₃ single crystal piezoelectric materials and ZnO thin film piezoelectric materials have been applied as SAW (Surface Acoustic Wave) filters. Thin film piezoelectric materials such as AlN and ZnO have been studied in the newly developed FBAR (Film Bulk Acoustic wave Resonator) bandpass filter material. PZT ceramics, which is a polycrystalline piezoelectric material, is most widely applied to ultrasonic vibrators, filters, resonators, ignition devices and sensors because of its excellent processability and various piezoelectric characteristics and low cost. Polymer piezoelectric materials and PZT composite piezoelectric materials are mainly applied to various keyboards, underwater acoustic parts, and medical transducers because they are easy to process into sheet form due to the characteristics of materials.

In one embodiment of the present invention, PVDF was used as a piezoelectric material. PVDF, one of the polymer piezoelectric materials, exhibits piezoelectric effects several times larger than quartz. Unlike ceramics, which exhibit piezoelectric effects due to the crystal structure of the material, PVDF exhibits piezoelectric effects when elongated chains of molecules interact with each other by attracting and repelling each other when an electric field is applied. In addition, PVDF is not only resistant to corrosion, but also has superior material properties such as thermal stability and chemical resistance.

In the present invention, the thickness of the piezoelectric layer may preferably be 1 nm to 900 占 퐉, more preferably 10 nm to 100 占 퐉, and still more preferably 10 nm to 10 占 퐉. If the thickness of the piezoelectric layer is less than 1 nm, the control of the piezoelectric layer coating process may be difficult or the piezoelectric characteristics may be deteriorated. If the thickness exceeds 900 탆, the thickness of the fiber yarn may become too thick.

The term "conductive polymer" used in the present invention refers to an organic polymer having conductivity capable of conducting electricity, and the conductive polymer may have the same conductivity as a metal or exhibit a semiconductor characteristic.

The conductive polymer has a conjugation structure in which CC bonds and C═C bonds are alternately present, and the conductivity is varied depending on the type of monomer, polymerization method, degree of doping, and type of dopant . In addition, the conductive polymer has electric conductivity and can be formed into a dispersion solution, and is easy to be coated or mixed with other materials by using the conductive polymer, and the film can be manufactured by various methods. Since the conductive polymer is an organic material, it is lighter in weight, less expensive, and has a very simple process so that it can replace the existing metal compound-based electrode material and can be used as a transparent electrode.

In the present invention, the conductive polymer may be at least one selected from the group consisting of polyacetylene, polypyrrole, polythiophene, poly (3-alkyl-thiophene), polyphenylene sulfide, polyphenylene vinylene, polythienylene vinylene, Isocyanatethene, isothianaphthene, polylaurene, polyfuran and polyaniline, but is not limited thereto.

In addition, the conductive polymer may be doped with a suitable impurity. As in the case of semiconductors, these polymers can be made either n-type (free electron dominant) or p-type (i.e., hole dominant) depending on the type of impurity. Unlike semiconductors, however, these impurities do not change the polymeric atom and lattice position or exist as a substitute. Examples of the doping material include, but are not limited to, bromine, iodine, and AsF ₅ .

In the present invention, the thickness of the conductive polymer layer may be 1 nm to 900 占 퐉, more preferably 10 nm to 100 占 퐉, and still more preferably 10 nm to 10 占 퐉. If the thickness of the conductive polymer layer is less than 1 nm, control of the conductive polymer layer coating process may be difficult or electrode characteristics exhibited by the conductive polymer layer may be deteriorated. If the thickness exceeds 900 탆, the thickness of the fiber layer may become too thick.

According to another aspect of the present invention, there is provided a method of manufacturing a piezoelectric fiber yarn, comprising the steps of: (1) forming a piezoelectric layer on a surface of a core conductive fiber yarn; And forming a conductive polymer layer on the surface of the piezoelectric layer (step 2).

The step 1 is a step of forming a piezoelectric layer that exhibits piezoelectric characteristics on the surface of the core conductive fiber yarn.

The core conductive fiber yarn and the kind of the piezoelectric material and the thickness of the piezoelectric layer are the same as those described in the piezoelectric fiber yarn.

Step 2 is a step of forming a conductive polymer layer on the surface of the piezoelectric layer, which exhibits an electrode characteristic.

The kind of the conductive polymer and the thickness of the conductive polymer layer are the same as those described in the piezoelectric fiber yarn.

In the present invention, the step 1) and the step 2) may be carried out by a spray coating method or a dip coating method.

The present invention also provides a piezoelectric fabric woven with the piezoelectric fiber yarn.

The present invention also provides a piezoelectric garment product made using the above-described piezoelectric fabric.

In the present invention, when the piezoelectric characteristic is exhibited in the piezoelectric layer according to the movement of the body by using the piezoelectric fabric, the core conductive fiber yarn and the conductive polymer layer function as an electrode, so that an electric signal can be detected Thereby providing a piezoelectric garment product (see Figs. 2 and 3).

The change in the pressure due to the movement of the body changes the surface charge on the surface of the piezoelectric fiber yarn and the changed surface charge can be transmitted to the input device through the current-voltage conversion device and the amp circuit.

The present invention also provides a coated piezoelectric sensor manufactured using the piezoelectric fiber yarn.

The piezoelectric material coated on the core conductive fiber yarn, that is, the piezoelectric layer has piezoelectricity by the movement of the body, and the electrodes on the inner and outer surfaces of the piezoelectric layer can detect the surface charge change value of the piezoelectric layer, .

In the present invention, the coated piezoelectric sensor may be a body-worn type or a body-attached type. That is, the coated type piezoelectric sensor may include both a form to be worn in a garment form and a form to be attached to a body.

In the present invention, the coated piezoelectric sensor may be one that senses an electromyogram, an electrocardiogram, a breathing conduction, or a thigh muscle motion signal.

As one embodiment, it can be applied to a smart fiber device as a sensor for measuring motion signals of muscles as shown in Fig.

As another embodiment, it can be applied to a smart fiber device as a sensor for measuring electrocardiogram as shown in Fig.

The present invention can provide a piezoelectric fiber yarn which can be used for signal detection without coating an additional electrode by coating the piezoelectric thin film on the fiber itself used for weaving clothes. Further, according to the present invention, by using the piezoelectric fiber yarn, it is possible to provide a clothes product and a covered piezoelectric sensor which do not require a separate electrode and are excellent in activity.

1 schematically shows a structure of a piezoelectric fiber yarn according to an embodiment of the present invention using PVDF as a piezoelectric material.
Fig. 2 schematically shows an embodiment applied to a smart fiber device as a sensor for measuring muscle motion signals. Fig.
Fig. 3 schematically shows an embodiment applied to a smart fiber device as a sensor for measuring electrocardiogram.
4 is a result of scanning electron microscopy (SEM) of the cross-sectional shape of the piezoelectric fiber yarn of the present invention.
5 is a schematic view illustrating a process of fabricating a piezoelectric device using the piezoelectric fiber yarn of the present invention and examining its piezoelectric characteristics.
6 shows the results of piezoelectric property measurement of a piezoelectric device using the piezoelectric fiber yarn of the present invention.

Hereinafter, the present invention will be described in more detail with reference to Examples. These embodiments are only for describing the present invention more specifically, and the scope of the present invention is not limited by these examples.

Example  1: Piezoelectricity of the present invention Fiber yarn  Produce

A conductive fiber yarn was used as a core part from CK International (Canada), and the piezoelectric fiber yarn of the present invention was produced using PVDF (number average molecular weight: 534,000) as a piezoelectric material and polyacetylene (number average molecular weight: 74,000) as a conductive polymer Respectively.

First, 1 wt% of PVDF was added to 100 ml of N-methyl-2-pyrrolidone (NMP) and stirred, followed by ultrasonic treatment to prepare a PVDF solution. The PVDF solution was spray coated on the core conductive fiber yarn and heated to 210 ° C to remove the NMP to obtain a conductive fiber yarn coated with the PVDF layer.

1 wt% of polyacetylene was added to 100 ml of toluene under nitrogen gas and stirred, followed by ultrasonic treatment to prepare a polyacetylene solution. The polyacetylene solution was spray coated on the PVDF layer-coated conductive fiber yarn and heated at a temperature of 150 ° C to remove toluene to obtain the piezoelectric fiber yarn of the present invention.

Example  2: Piezoelectricity of the present invention Fiber yarn  Manufacture of used fabrics

The piezoelectric fiber yarn prepared in Example 1 was woven to produce a piezoelectric fabric.

Experimental Example  1: Piezoelectricity of the present invention Textile  Investigation of physical and chemical properties

The sectional shape of the piezoelectric fiber yarn of the present invention prepared in Example 1 was examined by a scanning electron microscope (SEM), and the results are shown in FIG.

4, it can be seen that the piezoelectric material layer and the conductive polymer layer are formed on the surface of the core conductive fiber yarn, so that the piezoelectric fiber yarn of the present invention has a multilayer structure.

Experimental Example  2: Piezoelectricity of the present invention Fiber yarn  Piezoelectric Device  Investigation of piezoelectric properties

A piezoelectric device was fabricated as shown in FIG. 5 using the piezoelectric fiber yarn of the present invention manufactured in Example 1, and its piezoelectric characteristics were examined.

Specifically, the piezoelectric device is formed by coating a piezoelectric fiber sheet on a conductive fiber substrate and coating a conductive thin film on the surface of the piezoelectric fiber sheet.

The results are shown in Fig.

6, it can be confirmed that the piezoelectric device using the piezoelectric fiber yarn of the present invention can exhibit piezoelectric characteristics. FT-IR analysis confirmed a peak at 1273 cm <" ¹ > for the beta phase with piezoelectric polymer properties.

Claims (17)

Core conductive fiber yarns;
A piezoelectric layer formed on a surface of the core conductive fiber yarn; And
And a conductive polymer layer formed on the surface of the piezoelectric layer by a dip coating method,
Wherein the conductive polymer is polyacetylene, and the thickness of the conductive polymer layer is 1 nm to 100 m.
The piezoelectric fiber yarn according to claim 1, wherein the core conductive fiber yarn has a resistance per 1 cm of short fibers of 10 ¹² Ω to 10 ¹⁵ Ω.
The piezoelectric fiber yarn according to claim 1, wherein the core conductive fiber yarn is characterized in that a conductive layer is formed on the surface or inside of the fiber yarn, or conductive particles are dispersed in the fiber yarn.
The piezoelectric fiber yarn according to claim 3, wherein the fiber yarn is made of a synthetic polymer, a natural polymer, or a mixed polymer thereof.
The piezoelectric fiber yarn according to claim 3, wherein the conductive layer or conductive particles are carbon or metal.
6. The piezoelectric fiber yarn according to claim 5, wherein the metal is selected from the group consisting of Ag, Au, Pt, Cu, Ti, Al, V, Cr, Mn, Fe, Co and Ni.
The method of claim 1, wherein the piezoelectric layer is _{α-AlPO 4, α-SiO} 2, LiTaO 3, LiNbO 3, Pb 5 -Ge 3 O 11, Tb 2 (MoO 4) 3, Li 2 B 4 O 7, CdS Pb (Zn _2/3 Nb _1/3 ) O ₃ -PbTiO ₃ ], PMN-PT [Pb (Mg _2/3 Nb _1/3 )], ZnO, Bi ₁₂ SiO ₂₀ , Bi ₁₂ GeO ₂₀ , PZN- O ₃ -PbTiO _3], tree glycine sulfate (triglycine sulfate, TGS), PZT (lead zirconate titanate, PbZrO 3 -PbTiO 3), PT (PbTiO 3), PZT- composite perovskite (PZT-complex perovskite), _{BaTiO 3, ZnO, CdS, AlN} , polyvinylidene fluoride (polyvinylidene fluoride, PVDF), poly (vinylidene fluoride-co-ethylene-trifluoromethyl [poly (vinylidene fluoride-co- trifluoroethylene), P (VDF-TrFE Polyvinylidene fluoride-co-tetrafluoroethylene, P (VDF-TeFE)], PZT-PVDF, PZT-silicone rubber, PZT-Epoxy, PZT-foamed urethane, or a mixture thereof.
The piezoelectric fiber yarn according to claim 1, wherein the piezoelectric layer has a thickness of 1 nm to 900 占 퐉.
delete delete 9. A method for producing a piezoelectric fiber yarn according to any one of claims 1 to 8, comprising the steps of:
Forming a piezoelectric layer on the surface of the core conductive fiber yarn (step 1); And
And forming a conductive polymer layer on the surface of the piezoelectric layer (step 2).
delete 9. A piezoelectric fabric woven with the piezoelectric fiber yarn of any one of claims 1-8.
A piezoelectric garment product made using the piezoelectric fabric of claim 13.
A coated piezoelectric sensor manufactured by using the piezoelectric fiber yarn of any one of claims 1 to 8.
The coating type piezoelectric sensor according to claim 15, wherein the coated type piezoelectric sensor is a body wearing type or a body type.
16. The coated piezoelectric sensor according to claim 15, wherein the coated piezoelectric sensor senses an EMG, electrocardiogram, respiratory conduction, or thigh muscle motion signal.

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