KR102026011B1 - Fiber-based sensors and method of manufacturing the same - Google Patents

Abstract

The present invention relates to a fibrous sensor and a method of manufacturing the same. The fibrous sensor according to an embodiment of the present invention comprises a stretchable fiber and a conductive fiber made of metal nanoparticles formed inside the stretchable fiber; And a conductive stretch fiber comprising a conductive polymer formed on the surface of the conductive fiber, wherein the conductive stretch fiber is made of a first conductive stretch fiber and a second conductive stretch fiber, and the conductive stretch fiber is a surface structure formed on the surface. And a twisted structure in which the first conductive stretched fiber and the second conductive stretched fiber are twisted with each other, and the first conductive stretched fiber and the second conductive stretched fiber each have a single resistance in the fiber. And the first conductive stretchable fiber and the second conductive stretchable fiber form mutual resistance therebetween.

Description

FIBER-BASED SENSORS AND METHOD OF MANUFACTURING THE SAME

The present invention relates to a fibrous sensor and a method for manufacturing the same, and more particularly, a high-performance fibrous sensor and a method for manufacturing the same that can clearly detect and detect various types of external stimuli such as vertical pressure, bending force, tensile force and shear force. It is about.

Recently, the demand and interest of wearable devices have been steadily increasing, and various types of products have been released.

The wearable device has a large share in order of wrist type (42%), clothing type (35%), earring type (21%), and shoe type (20%), followed by the clothing type wearable device. It has a 19% share and is gradually expanding (Source: 2014 'North American Consumer Technographics survey).

Among the components of the clothing type wearable device, the fiber type sensor element takes up a large portion, and various related researches and technology developments are in progress as high mechanical and chemical properties such as high elasticity, flexibility, physicochemical durability, and high sensitivity are required.

As a technology related to the existing fibrous sensor, a 'fiber-type temperature sensor manufacturing method' (Korean Registered Patent No. 10-1654025, Gumi Electronics & Information Technology Institute), 'Optical fiber vibration sensor and vibration measuring method using the same' (Korean Registered Patent No. 10-1612258, Pukyong National University Industry-University Cooperation Group), 'Optical fiber pressure sensor and pressure measuring method using the same' (Korea Patent No. 10-1653908, Pukyong National University Industry-Academic Cooperation Group) and other technologies using optical fibers are mainly developed.

However, due to the characteristics of the optical fiber, a photoelectric conversion device is required, and there are disadvantages in creating a communication failure and electromagnetic waves. In addition, it is difficult to connect and expand, so it is difficult to apply the actual clothing in one piece.

Representative fiber pressure sensor technology, 'conductive nanofibers and its manufacturing method, and conductive nanofiber-based pressure sensor and its manufacturing method' (Korea Patent No. 10-1541461, Yonsei University Industry-Academic Cooperation Foundation) A fibrous pressure sensor technology based on conductive fibers coated with a polymer and forming a large amount of metal nanoparticles inside the polymer has been proposed.

The pressure sensor precisely measured the micro pressure corresponding to 8 mg by an electrostatic method in which the conductive fibers coated with the dielectric material were cross-arranged, and showed repeated durability of 10 ⁵ cycles or more. In addition, the pressure sensor responds to other types of stimuli such as stretching and bending in addition to the pressure stimulation in the vertical direction. However, the pressure sensor has a limitation in that it is difficult to accurately determine what type of stimulus is given only by the resulting signal.

This problem is a limitation of most conventional pressure sensors including film types in addition to the fibrous sensor. The development of a fibrous sensor that can detect and detect various types of stimuli such as vertical pressure, bending force, tensile force, and shear force can be detected. need.

An object of the present invention is to form a fiber having high elasticity and high conductivity by forming a metal nanoparticles having excellent conductivity in the stretchable fiber excellent in elasticity.

It is also an object of the present invention to provide a technique for coating a conductive polymer (particularly a pressure sensitive polymer) on the surface of a fiber having high elasticity and high conductivity, and forming various surface structures on the surface.

In addition, an object of the present invention is to form a fibrous sensor having a higher sensitivity than the fibrous sensor having no surface structure by forming the surface structure on the surface of the conductive stretched fiber.

In addition, an object of the present invention is to produce a fibrous sensor that can twist the conductive stretched fiber formed with the surface structure twisted to determine the external stimulus such as vertical pressure, bending force, tensile force and shear force clearly.

The fibrous sensor according to an embodiment of the present invention comprises a stretchable fiber and a conductive fiber made of metal nanoparticles formed inside the stretchable fiber; And a conductive stretch fiber comprising a conductive polymer formed on the surface of the conductive fiber, wherein the conductive stretch fiber is made of a first conductive stretch fiber and a second conductive stretch fiber, and the conductive stretch fiber is a surface structure formed on the surface. And a twisted structure in which the first conductive stretched fiber and the second conductive stretched fiber are twisted with each other, and the first conductive stretched fiber and the second conductive stretched fiber each have a single resistance in the fiber. And the first conductive stretchable fiber and the second conductive stretchable fiber form mutual resistance therebetween.

The conductive fiber may have a hierarchical structure in which a plurality of stretchable fibers are arranged in parallel with each other.

According to an embodiment of the present invention, the surface structure may be a buckling structure.

According to another embodiment of the present invention, the surface structure may be a microstructure.

The microstructure may have any one shape selected from the group consisting of a cylinder, a square column, a hexagonal column, a cone, and a hemisphere.

The fibrous sensor may distinguish a type of external stimulus according to a change value of the single resistance and the mutual resistance.

The external magnetic pole may be at least one force selected from the group consisting of normal pressure, bending force, stretching force and shearing force.

The stretchable fiber may include any one selected from the group consisting of polyurethane, styrene-butadiene-styrene (SBS), styrene butadiene rubber (SBR), and polydimethylsiloxane (PDMS).

The metal nanoparticles may be any one selected from the group consisting of silver nanoparticles, gold nanoparticles, copper nanoparticles, and platinum nanoparticles.

The conductive polymer may be made of a pressure sensitive polymer.

The conductive polymer may include carbon black, silver nanowires, and polyurethane.

Method of manufacturing a fibrous sensor according to an embodiment of the present invention comprises the steps of forming a conductive fiber consisting of stretchable fibers and metal nanoparticles formed in the stretchable fibers; Coating a conductive polymer on the surface of the conductive fiber to form conductive stretch fiber, and forming a surface structure on the surface of the conductive stretch fiber; And twisting the two conductive stretch fibers with each other to form a twisted structure.

According to an embodiment of the present invention, the step of forming a conductive stretch fiber by coating a conductive polymer on the surface of the conductive fiber, and forming a surface structure on the surface of the conductive stretch fiber, extending the conductive fiber in the longitudinal direction ; Coating a conductive polymer on the surface of the stretched conductive fiber; And restoring the conductive fiber coated with the conductive polymer to its original state to form a buckling structure.

According to another embodiment of the present invention, the step of forming a conductive stretch fiber by coating a conductive polymer on the surface of the conductive fiber, and forming a surface structure on the surface of the conductive stretch fiber coating the conductive polymer on the surface of the conductive fiber Doing; And forming a microstructure by imprinting the conductive fiber coated with the conductive polymer using a mold having a pattern of the microstructure formed thereon.

Forming the conductive fiber made of the stretchable fiber and the metal nanoparticles formed in the stretchable fiber may include absorbing the metal nanoparticles in the stretchable fiber.

Coating the conductive polymer may include flowing a conductive polymer-containing solution along a length direction of the conductive fiber.

In order to develop a wearable device or a clothing-integrated device for effective motion sensing, it is necessary to distinguish and distinguish various stimuli such as bending force (bending), tensile force (stretching) and shear force as well as vertical pressure in the vertical direction. . However, most of the conventionally invented sensors have been developed to be limited to one stimulus, and there are limitations in the determination and detection of various external stimuli. High-performance fibrous sensor according to an embodiment of the present invention can overcome the limitations of these conventional sensors.

The high-performance fibrous sensor according to the embodiment of the present invention has a high elasticity (flexibility) based on the elastic fibers, high conductivity based on the metal nanoparticles and the conductive polymer, and due to the surface structure and the twist structure formed on the surface It has high signal sensitivity by maximizing the change of the sensor's resistance to external stimulus.

In addition, the high-performance fibrous sensor according to the embodiment of the present invention is a contact resistance method, measuring a change in the mutual resistance (mutual resistance) between the single resistance (single resistance) and different fibers of a single fiber, respectively, as well as the vertical pressure In addition, various types of external stimuli such as bending force, tensile force and shear force can be clearly identified, detected, and measured.

In addition, since the high-performance fibrous sensor according to the embodiment of the present invention minimizes noise by using a contact resistance method and does not require a separate conversion device, clothes are manufactured by manufacturing in a fiber form using existing garment weaving technology. It can be easily applied to shoes, gloves and hats, so it can be conveniently applied as a clothing-integrated wearable sensor.

1 is a view showing the configuration of a fibrous sensor according to an embodiment of the present invention.
2 is a view for explaining the configuration of the resistance of the fibrous sensor according to an embodiment of the present invention.
3 is a view showing a response when various stimuli are applied to the fibrous sensor according to an embodiment of the present invention.
Figure 4 is a graph showing the response when the vertical pressure is applied to the fibrous sensor according to an embodiment of the present invention.
Figure 5 is a graph showing the response when the bending force is applied to the fibrous sensor according to an embodiment of the present invention.
Figure 6 is a graph showing the response when the tensile force is applied to the fibrous sensor according to an embodiment of the present invention.
Figure 7 is a graph showing the response when the 40% tensile force is applied to the fibrous sensor according to an embodiment of the present invention.
8 is a flowchart of a method of manufacturing a fibrous sensor according to an embodiment of the present invention.
9 is a view for explaining a method of forming a buckle structure according to an embodiment of the present invention.
10 is a view for explaining a method of forming a microstructure according to an embodiment of the present invention.
11 is an electron micrograph of a fibrous sensor having a buckle structure constructed in accordance with an embodiment of the present invention.
12 is an electron micrograph of a fibrous sensor having a cylindrical microstructure manufactured according to an embodiment of the present invention.
13 is an electron micrograph of a fibrous sensor having a conical microstructure manufactured according to an embodiment of the present invention.
14 and 15 are tables and graphs showing the change in conductivity and the shape of the microstructure when the content of the conductive polymer is changed according to the embodiment of the present invention.
16 to 18 are graphs showing the degree of sensitivity improvement of a fibrous sensor having a microstructure manufactured according to an embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings and the contents described in the accompanying drawings, but the present invention is not limited or limited to the embodiments.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

As used herein, the terms "comprise", "have" or "include" are intended to indicate that there is a feature, number, step, action, component, part, or combination thereof described in the specification, It should be understood that it does not exclude in advance the possibility of the presence or addition of one or more other features or numbers, steps, actions, components, parts or combinations thereof.

In addition, as used herein, "embodiments", "examples", "sides", "examples", and the like are any aspect or design described as being better or advantageous than other aspects or designs. It should not be interpreted.

In addition, the term "or" as used herein means an inclusive OR "inclusive or" rather than an exclusive OR "exclusive or". That is, unless stated otherwise or unclear from the context, the expression "x uses a or b" means any one of natural inclusive permutations.

Also, the singular forms “a” or “an”, as used herein, should be construed generally to mean “one or more” unless the context clearly indicates otherwise or in the singular form. do.

Also, when a part of a film, layer, region, component or the like is said to be "on" or "on" another part, it is not only when it is directly above another part, but also another film, layer, area in between. It also includes the case where components, etc. are intervened.

In addition, although terms such as “first” or “second” may be used herein to describe various components, the components should not be limited by the terms. The terms are only for the purpose of distinguishing one component from another, for example, without departing from the scope of the claims according to the inventive concept, the first component may be named as a second component, Similarly, the second component may also be referred to as the first component.

Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art. Terms such as those defined in the commonly used dictionaries should be construed as having meanings consistent with the meanings in the context of the related art, and are not construed in ideal or excessively formal meanings unless expressly defined herein. Do not.

Hereinafter, with reference to the drawings will be described a specific embodiment of the present invention; However, the spirit of the present invention is not limited to such an embodiment, and the spirit of the present invention may be proposed differently by the addition, change, deletion, etc. of the elements constituting the embodiment, but this is also included in the spirit of the present invention. Will be.

1 is a view showing the configuration of a fibrous sensor according to an embodiment of the present invention.

Referring to FIG. 1, the fibrous sensor includes conductive stretchable fiber 100.

The conductive stretchable fiber 100 may be formed of the first conductive stretchable fiber 110 and the second conductive stretchable fiber 120. In addition, although the conductive stretch fiber is not shown in the drawings, for example, it may be composed of a plurality of third, fourth or more conductive stretch fibers.

The conductive stretchable fiber 100 has a twist structure. Specifically, the conductive stretchable fiber 100 may have a twist structure in which the first conductive stretchable fiber 110 and the second conductive stretchable fiber 120 are twisted with each other. In addition, although the conductive stretch fibers are not shown in the drawings, for example, when the third, fourth or more plurality of conductive stretch fibers are formed, the plurality of conductive stretch fibers may have a twisted structure in which twists are twisted with each other. have.

The twist structure is a sensor that distinguishes external stimuli by causing a change in electrical resistance to external stimuli when measuring the electrical resistance of each of the first conductive stretched fiber 110 and the second conductive stretched fiber 120 and the two fibers. Allows you to implement At this time, the twisted structure in which the two fibers are twisted is a sensor structure that maximizes contact between the two fibers, which are one-dimensional structures.

The conductive stretchable fiber 100 having a twisted structure may have a thickness of 70 μm to 350 μm depending on the number of deniers of the stretchable fiber, and a thickness of 100 μm to 200 μm may be preferable for implementing the sensor. When the thickness of the conductive stretchable fiber 100 having a twisted structure is less than 100 μm, it is difficult to form a surface structure for developing a sensor. In addition, when the thickness of the conductive stretched fiber 100 of the twisted structure exceeds 200 μm, it may be difficult when the conductive stretched fiber is woven into a commercial fabric for later application of the sensor.

The conductive stretchable fiber 100 has a surface structure formed on the surface through the coating and structure forming step of the conductive polymer.

The surface structure may be formed on the surface of the conductive stretchable fiber 100 to maximize the change in resistance of the sensor to external stimuli, thereby improving signal sensitivity of the sensor.

Specifically, the surface structure serves as a spacer to increase the mutual resistance of the first conductive stretched fiber 110 and the second conductive stretched fiber 120 when the sensor is implemented by twisting the conductive stretched fiber 100. In addition, the contact surface area increases when an external stimulus is applied, thereby greatly reducing the mutual resistance, thereby allowing the sensor to have high signal sensitivity (see FIG. 15).

According to an embodiment of the present invention, the surface structure may be a buckling structure or a microstructure.

The buckling structure refers to a structure having a fine wavy shape in which fine convex portions and concave portions are formed on the surface by applying compressive stress to the coated conductive polymer using the elastic force of the conductive stretchable fiber 100 (FIG. 9 (c)). And FIG. 11).

The buckling structure can be three-dimensionally formed by a buckling structure forming method. The method of forming the buckling structure will be described later with reference to FIG. 9.

The buckling structure can adjust the wavelength and amplitude of the convex and concave portions of the shape of the buckled surface according to the coating thickness of the conductive polymer and the degree of extension of the conductive stretchable fiber 100.

The fine structure refers to a fine convex and concave structure formed on the surface of the conductive stretchable fiber 100, and the convex portion includes protrusions extending to the surface of the material, and the concave portion of the material And grooves extending on the surface thereof (see FIGS. 12 and 13).

The microstructure may have various shapes such as, for example, columnar shapes such as cylinders, square columns, or hexagonal columns, horn shapes such as cones, square pyramids, or triangular pyramids, or hemispheres.

The microstructures can be formed three-dimensionally by an imprinting method. A method of forming a microstructure using an imprinting method will be described later with reference to FIG. 10.

The conductive stretchable fiber 100 means a fiber having both conductivity and stretchability, and the conductive stretchable fiber 100 includes a conductive fiber and a conductive polymer.

Conductive fibers include stretchable fibers and metal nanoparticles.

Stretchable fibers refers to stretchable fibers, including polyurethane, styrene-butadiene-styrene (SBS), styrene butadiene rubber (SBR), polydimethylsiloxane (PDMS), or silicone-based rubber materials can do.

In particular, the elastic fibers may comprise polyurethane, which is based on high elasticity (500% to 700%), low modulus of elasticity and high elastic recovery (95% to 99%), high to chemicals. Its mechanical and chemical properties are very good for developing conductive stretchable fibers such as stability.

Metal nanoparticles (NWs) refer to nanoscale nanoparticles made of a conductive metal material, and are formed inside the stretchable fiber. Specifically, the metal nanoparticles are absorbed in the stretchable fibers, and a plurality of metal nanoparticles may be randomly distributed on the inside and the surface of the stretchable fibers.

The plurality of metal nanoparticles may have an average diameter of, for example, 0.1 nm to 200 nm, but is not limited thereto.

The content of the plurality of metal nanoparticles may be adjusted according to the degree of absorption into the stretchable fiber. The plurality of metal nanoparticles may be included in a large amount in the stretchable fiber in an amount of 60 wt% to 90 wt%, but in order to form the surface structure, it is preferable to utilize the stretchable (elastic) property of the stretchable fiber (elastic fiber). Accordingly, when implementing conductive stretch fibers having a surface structure that ensures sufficient electrical conductivity and elastic force, it is effective to use conductive fibers containing about 60% by weight of metal nanoparticles.

The metal nanoparticles may be silver (Ag) nanoparticles, gold (Au) nanoparticles, copper nanoparticles (Cu), or platinum (Pt) nanoparticles. The conductive fiber may have a hierarchical structure. Specifically, the conductive fiber may have a hierarchical structure in which a plurality of stretchable fibers are arranged in parallel to each other in the longitudinal direction. Here, the plurality of stretchable fibers may be composed of one strand by joining each of the stretchable fibers to each other. The conductive fibers may be, for example, 2 to 100, but is not limited thereto.

Electrically conductive polymers are formed by coating the surface of the conductive fiber.

The conductive polymer refers to a polymer having conductivity, and by forming a conductive polymer having a different electrical conductivity from the conductive fiber on the surface of the conductive fiber, it is possible to improve the ability to distinguish between the single resistance and the mutual resistance when used as a sensor.

Conductive polymers may be made of pressure sensitive polymers capable of changing electrical properties in response to external pressure. The pressure sensitive polymer mixes a conductive material with a rubber-like polymer material, so that when the external pressure is applied, the gap between the conductive materials decreases and the conductivity increases. The pressure sensitive polymer may further include a material having a lower conductivity than metal nanoparticles, and may include carbon black, carbon nanotubes (CNT), silver nanowires (Ag NWs), polyurethanes, and combinations thereof. Can be.

According to an embodiment of the invention, the conductive polymer may include carbon black, silver nanowires and polyurethane.

The conductive stretchable fiber 100 according to the embodiment of the present invention has a high stretch (flexibility) based on the stretchable fiber, has a high conductivity based on the metal nanoparticles and the conductive polymer, and has a surface structure and a twist structure formed on the surface. It can be used as a fibrous sensor that has a high signal sensitivity to discriminate, detect and measure external stimuli such as vertical pressure, bending force (flexion), tensile force (stretch) and / or shear force.

2 is a view for explaining the configuration of the resistance of the fibrous sensor according to an embodiment of the present invention.

Referring to FIG. 2, conductive twisted fibers having a twisted structure composed of first conductive stretched fibers and second conductive stretched fibers each form a single resistance in a single fiber. Further, the first conductive stretchable fiber and the second conductive stretchable fiber form mutual resistance by contact with each other.

Since the single resistance and the mutual resistance change in accordance with the type of external stimulus, the type of the external stimulus can be distinguished according to the change value (pattern) of the single resistance and the mutual resistance.

Specifically, a single resistance can be obtained by measuring the change in resistance of a single fiber, which can respond to strain stimulation based on the electrical connection of metal nanoparticles in the conductive fiber. In addition, mutual resistance can be obtained by measuring the change in contact resistance between two fibers and can respond to normal pressure stimulation in the vertical direction.

Therefore, by measuring these two resistance signals simultaneously, it is possible to determine what type of external stimulus is applied. Specifically, the external magnetic pole may be normal pressure, bending force, stretching force, shearing force, or the like.

High-performance fibrous sensor according to an embodiment of the present invention is a contact resistance method, by measuring the variation of the single resistance (single resistance) and the mutual resistance between the different fibers of the single fiber, respectively, as well as the vertical pressure and bending force Various types of external stimuli such as (bending), tensile (stretching) and shearing forces can be clearly identified, detected and measured.

 In addition, the fibrous sensor of the contact resistance method according to an embodiment of the present invention is manufactured in the form of fibers using existing garment weaving technology because it minimizes noise and does not require a separate conversion device using the contact resistance method. Therefore, it can be easily applied to clothes, shoes, gloves and hats, so that it can be conveniently applied as an integrated clothing wearable sensor.

3 is a view showing a response when various stimuli are applied to the fibrous sensor according to an embodiment of the present invention.

Referring to FIG. 3, the fibrous sensor according to an embodiment of the present invention is based on the form of two resultant signals of single resistance and mutual resistance, and the stimulus to be applied is any form of stimulus. Perceptual distinction can be distinguished.

Specifically, the fibrous sensor according to the embodiment of the present invention may have various types of external stimuli such as normal pressure, bending force, stretching force and shearing force. This can be distinguished by a change in resistance.

In addition, the fibrous sensor according to the embodiment of the present invention not only has a high sensitivity based on the surface structure, but also a quantitative analysis can be performed because the amount of change in the resulting signal varies depending on the intensity of the applied stimulus. .

Hereinafter, the resistance change of the fibrous sensor according to each external stimulus will be described in detail with reference to FIGS. 4 to 7.

Figure 4 is a graph showing the response when the vertical pressure is applied to the fibrous sensor according to an embodiment of the present invention.

Referring to FIG. 4, when normal pressure in the vertical direction is applied to the fibrous sensor according to an embodiment of the present invention, the single resistance sensitive to strain stimulation is not changed, but the vertical pressure is not changed. Mutual resistance sensitive to the stimulus decreased with each stimulus, and the decrease in the mutual resistance value was proportional to the intensity of the applied stimulus.

Specifically, the fibrous sensor according to the embodiment of the present invention was able to stably operate at a vertical pressure of 10 kPa up to 1,000 kPa, could detect 10 kPa without difficulty, and also detects a difference of 10 kPa units. Could.

Figure 5 is a graph showing the response when the bending force is applied to the fibrous sensor according to an embodiment of the present invention.

Referring to FIG. 5, when a bending force is applied to a fibrous sensor according to an embodiment of the present invention, a single resistance increases as a stimulus is applied, and mutual resistance Decreased. This can be analyzed by the fact that the bending force is a combination of the vertical pressure and strain stimulus is applied to the two stimulus at the same time.

Specifically, the fibrous sensor according to the embodiment of the present invention was able to operate stably for a bending force from 20 ° up to 180 °, in the case of mutual resistance may not be large difference in the value at a large angle, This could be solved through the application of surface structures.

Figure 6 is a graph showing the response when the tensile force is applied to the fibrous sensor according to an embodiment of the present invention.

Referring to FIG. 6, when a stretching force is applied to a fibrous sensor according to an embodiment of the present invention, a single resistance and mutual resistance simultaneously increase as a stimulus is applied. . This may be attributed to the fact that the electrical resistance of the conductive fibers and conductive polymer materials constituting the fibrous sensor increases rapidly when strain stimulation is applied.

Specifically, the fibrous sensor according to the embodiment of the present invention could operate stably for a tensile force of 10% to up to 60%.

Figure 7 is a graph showing the response when the 40% tensile force is applied to the fibrous sensor according to an embodiment of the present invention.

Referring to FIG. 7, it can be seen that mutual resistance (mutual resistance) exhibits a characteristic response when a tensile force and a restoring force are sequentially applied to a fibrous sensor according to an embodiment of the present invention. .

Specifically, in the fibrous sensor according to the embodiment of the present invention, when other stimuli such as vertical pressure and bending force are generally applied, the change in mutual resistance only occurs in the same direction, while when a tensile force is applied, the stimulus is applied. It can be seen that the resistance tends to decrease and then increase. In addition, it was confirmed that the resistance tends to decrease and then increase in the restoration process of returning the increased sensor.

  The characteristic signal of the fibrous sensor for the tensile force can be analyzed that when the tensile force is applied, the conductive elastic fibers of the twisted structure are forced in the direction of the central axis, and each conductive elastic fiber is subjected to strain stimulation. have. In the low-strain region where the stretching stimulus begins, the resistance decreases as the contact area between the two conductive stretch fibers increases, but as the stimulus grows beyond a certain area, the resistance of the conductive fiber and the conductive polymer itself is increased. This rapid increase can be analyzed to increase the overall mutual resistance.

Based on these results, the fibrous sensor according to the embodiment of the present invention can be determined using the characteristic response of the mutual resistance as well as the signal form of the single resistance and mutual resistance when a tensile force is applied.

Hereinafter, a method of manufacturing a fibrous sensor according to an embodiment of the present invention will be described with reference to FIG. 8.

8 is a flowchart of a method of manufacturing a fibrous sensor according to an embodiment of the present invention.

Referring to Figure 8, the manufacturing method of the fibrous sensor according to an embodiment of the present invention to form a conductive fiber made of a stretchable fiber and metal nanoparticles formed inside the stretchable fiber (S110), the surface of the stretchable fiber Forming a conductive stretch fiber by coating a conductive polymer, and forming a surface structure on the surface of the conductive stretch fiber (S120) and twisting the two conductive stretch fibers with each other to form a twisted structure (S130). It includes.

Hereinafter, each step of the manufacturing method of the fibrous sensor according to the embodiment of the present invention will be described in detail.

Step S110 is to form a conductive fiber made of a stretchable fiber and metal nanoparticles formed inside the stretchable fiber.

Specifically, step S110 may form a conductive fiber by absorbing the metal nanoparticles inside the stretchable fiber.

According to the embodiment, the elastic fibers are placed in the metal ion-containing solution containing the metal ions, and then taken out after a predetermined time to remove the residual solvent to absorb the metal ions inside the elastic fibers. Subsequently, when the metal ions absorbed into the stretchable fiber are reduced using a reducing agent or the like, the metal nanoparticles may be absorbed into the stretchable fiber, thereby forming conductive fibers in which the metal nanoparticles are absorbed into the stretchable fiber.

Step S120 is to form a conductive stretch fiber by coating a conductive polymer on the surface of the conductive fiber formed in step S110, and to form a surface structure on the surface of the conductive stretch fiber.

According to the embodiment, the method of coating the conductive polymer on the surface of the conductive fiber in step S120 by flowing the conductive polymer-containing solution along the longitudinal direction of the conductive fiber, or using a method of simply contacting the conductive polymer-containing solution to the conductive fiber The conductive polymer may be coated on the surface of the conductive fiber.

According to an embodiment, the buckling structure or the microstructure may be formed as the surface structure in step S120. Hereinafter, a method of forming a buckling structure will be described with reference to FIG. 9, and a method of forming a microstructure will be described with reference to FIG. 10.

9 is a view for explaining a method of forming a buckle structure according to an embodiment of the present invention.

Referring to FIG. 9, the step of forming the conductive stretched fiber 210 having the buckle structure formed thereon (see S120 of FIG. 8) may include (a) stretching the conductive fiber 211 in the longitudinal direction, and (b) Coating the conductive polymer 212 on the surface of the stretched conductive fiber 211 and (c) restoring the conductive fiber coated with the conductive polymer to its original state to form the buckle structure 213. have.

In the step (a), the length of the conductive fiber 211 is stretched by about 200% to 400% of the original length. If the elongation is lower than 200%, sufficient compressive stress may not be applied to the conductive polymer, so that the buckling structure may not be formed. When the elongation is higher than 400%, an compressive stress is excessively applied to the conductive polymer to be coated, so that the compressive stress remains even when the buckling structure is formed, thereby causing an undesirable effect such as twisting the conductive fiber.

In the step (b), the coating thickness of the conductive polymer 212 may be adjusted according to the number of coating of the conductive polymer 212. At this time, the coating thickness can be adjusted to adjust the wavelength and amplitude of the convex portion and the concave portion of the buckle structure.

In the step (c), the conductive fiber coated with the conductive polymer is restored to its original state to form the buckle structure 213. In this case, heat may be applied to the conductive fibers to help restore the conductive fibers.

10 is a view for explaining a method of forming a microstructure according to an embodiment of the present invention.

Referring to FIG. 10, the step of forming the conductive stretched fiber 310 having a microstructure formed on the surface thereof (see S120 of FIG. 8) may include (a) preparing the conductive fiber 311 and (b) conductive fiber 311. Coating the conductive polymer 312 on the surface of the c) and (c) imprinting conductive fibers 311 coated with the conductive polymer using a mold having a microstructured pattern to form a fine structure 313. It may include.

According to an embodiment, the conductive fibers coated with the conductive polymer to be patterned are disposed between the molds having the cylindrical engraved pattern, and heat and pressure are applied to melt the conductive polymer coated on the surface of the conductive fibers to flow into the mold. By removing heat, hardening the conductive polymer and removing the pressure, a conductive stretched fiber having a microstructure formed on its surface can be produced.

The imprinting method uses a property of the elastic fiber that returns to its original shape when the pressure is removed even though it is temporarily deformed when the pressure is applied. The cross section of the elastic fiber may be elliptical, depending on the property of the elastic fiber. In addition, the heating temperature and pressure during imprinting may vary depending on the glass transition temperature of the stretchable fiber.

Referring back to FIG. 8, step S130 is to twist the two conductive stretchable fibers prepared in step S120 with each other to form a twisted structure.

Hereinafter, an electron micrograph of a fibrous sensor having various surface structures manufactured according to an embodiment of the present invention will be described in detail with reference to FIGS. 11 to 13.

11 is an electron micrograph of a fibrous sensor having a buckle structure constructed in accordance with an embodiment of the present invention.

Referring to FIG. 11, a fibrous sensor having a buckling structure manufactured according to an embodiment of the present invention may include a conductive fiber made of polyurethane (elastic fiber) and silver nanoparticles (metal nanoparticles) and a surface of the conductive fiber. It is based on conductive stretch fibers coated with a composite material (conductive polymer) of carbon black, silver nanowires and polyurethane, and has a buckle structure formed on the surface of the conductive stretch fiber (see (a)). The two conductive stretched fibers are twisted with each other to form a twisted structure, it was confirmed that consisting of a single string (see (b)).

12 is an electron micrograph of a fibrous sensor having a cylindrical microstructure manufactured according to an embodiment of the present invention.

Referring to FIG. 12, a fibrous sensor having a cylindrical microstructure manufactured according to an embodiment of the present invention includes a conductive fiber made of polyurethane (elastic fiber) and silver nanoparticles (metal nanoparticles) and the conductive fiber. It is based on conductive stretch fibers coated with a composite material (conductive polymer) of carbon black, silver nanowires and polyurethane on the surface, and has a cylindrical microstructure on the surface of the conductive stretch fiber (see (a)). In addition, the two conductive stretched fibers in which the cylindrical microstructures were formed were twisted together to form a twisted structure, and were formed in a single string form (see (b)).

13 is an electron micrograph of a fibrous sensor having a conical microstructure manufactured according to an embodiment of the present invention.

Referring to FIG. 13, the fibrous sensor manufactured according to the embodiment of the present invention has a conical shape (30 μm in diameter and 30 μm in height) as well as a cylindrical fine structure (see FIG. 12) on the surface of the conductive stretchable fiber. It was confirmed that the structure can be formed (see (a) and (b)).

14 and 15 are tables and graphs showing the change in conductivity and the shape of the microstructure when the content (composition) of the conductive polymer is changed according to the embodiment of the present invention.

Referring to FIG. 14, the fibrous sensor manufactured according to the embodiment of the present invention is a conductive fiber made of polyurethane (elastic fiber) and silver nanoparticles (metal nanoparticles) and carbon black (CB) on the surface of the conductive fiber. Based on the conductive stretch fiber coated with a composite material (conductive polymer) of silver nanowires (Ag NWs) and polyurethane (PU), a microstructure is formed on the surface of the conductive stretch fiber.

Herein, the content (composition) of polyurethane (PU) carbon black (CB) and silver nanowires (Ag NWs), which are the constituent materials thereof, was adjusted as shown in FIG. 14.

The fibrous sensor manufactured according to the embodiment of the present invention has an electrical conductivity (conductivity) as the ratio of the conductive material (carbon black (CB) + silver nanowire (Ag NWs)) to the polyurethane (PU) increases. Was confirmed to increase. However, when the ratio of the conductive material is higher than the specific ratio, it was confirmed that aggregation of the microstructures occurred on the surface, which hindered the formation of the microstructures.

Referring to Figure 15, it can be seen that there is an optimization interval ((CB + Ag NWs) / PU = about 0.6 ~ 0.9) for the content ratio of the conductive material to the polyurethane.

16 to 18 are graphs showing the degree of sensitivity improvement of a fibrous sensor having a microstructure manufactured according to an embodiment of the present invention. Specifically, FIG. 16 illustrates a change in resistance when normal pressure is applied to a fibrous sensor having a microstructure manufactured according to an embodiment of the present invention, and FIG. 17 is manufactured according to an embodiment of the present invention. FIG. 18 shows a change in resistance when a bending force is applied to a fibrous sensor having a microstructure, and FIG. 18 shows a stretching force to be applied to a fibrous sensor having a microstructure manufactured according to an embodiment of the present invention. The resistance change in the case is shown.

16 to 18, when vertical pressure, bending force, and tensile force are respectively applied to a fibrous sensor pattern having a microstructure manufactured according to an embodiment of the present invention, the microstructure is not formed (Non -pattern), it was confirmed that the sensitivity of the fibrous sensor was improved.

As described above, the present invention has been described by way of limited embodiments and drawings, but the present invention is not limited to the above embodiments, and those skilled in the art to which the present invention pertains various modifications and variations from such descriptions. This is possible. Therefore, the scope of the present invention should not be limited to the described embodiments, but should be determined not only by the claims below but also by the equivalents of the claims.

Claims (16)

Conductive fibers comprising elastic fibers and metal nanoparticles formed in the elastic fibers; And
Conductive polymer formed on the surface of the conductive fiber
Conductive stretch fiber comprising a,
The conductive stretch fiber is made of a first conductive stretch fiber and a second conductive stretch fiber including a surface structure formed based on the conductive polymer formed on the surface,
The first conductive stretchable fiber and the second conductive stretchable fiber have a twist structure twisted in a twisted state in contact with each other,
And the first conductive stretchable fiber and the second conductive stretchable fiber each form a single resistance in the fiber, and the first conductive stretchable fiber and the second conductive stretchable fiber form mutual resistance therebetween.
The method of claim 1,
The fiber type sensor
And a type of external stimulus according to the change value of the single resistance and the mutual resistance.
The method of claim 1,
The conductive fiber
Fibrous sensor, characterized in that the elastic fibers are made of a plurality of hierarchical structure arranged in parallel to each other.
The method of claim 1,
The surface structure is
Fibrous sensor, characterized in that the buckling structure.
The method of claim 1,
The surface structure is
Fibrous sensor, characterized in that the fine structure.
The method of claim 5,
The microstructure is
A fibrous sensor, characterized in that it has any one shape selected from the group consisting of a cylinder, a square column, a hexagonal column, a cone and a hemisphere.
The method of claim 2,
The external stimulus is
At least one force selected from the group consisting of vertical pressure, bending force, tensile force and shear force.
The method of claim 1,
The stretchable fiber
A fibrous sensor comprising any one selected from the group consisting of polyurethane, styrene-butadiene-styrene (SBS), styrene butadiene rubber (SBR), and polydimethylsiloxane (PDMS).
The method of claim 1,
The metal nanoparticles are
Fibrous sensor, characterized in that any one selected from the group consisting of silver nanoparticles, gold nanoparticles, copper nanoparticles and platinum nanoparticles.
The method of claim 1,
The conductive polymer
A fibrous sensor comprising a pressure sensitive polymer.
The method of claim 1,
The conductive polymer
A fibrous sensor comprising carbon black, silver nanowires and polyurethane.
Forming a conductive fiber made of a stretchable fiber and metal nanoparticles formed inside the stretchable fiber;
Coating a conductive polymer on the surface of the conductive fiber to form conductive stretch fiber, and forming a surface structure on the surface of the conductive stretch fiber; And
Twisting the two conductive stretch fibers together to form a twisted structure
Method of manufacturing a fibrous sensor comprising a.
The method of claim 12,
Coating a conductive polymer on the surface of the conductive fiber to form conductive stretch fiber, and forming a surface structure on the surface of the conductive stretch fiber
Stretching the conductive fiber in a longitudinal direction;
Coating a conductive polymer on the surface of the stretched conductive fiber; And
Restoring the conductive fiber coated with the conductive polymer to its original state to form a buckling structure
Method of manufacturing a fibrous sensor comprising a.
The method of claim 12,
Coating a conductive polymer on the surface of the conductive fiber to form conductive stretch fiber, and forming a surface structure on the surface of the conductive stretch fiber
Coating a conductive polymer on a surface of the conductive fiber; And
Forming a microstructure by imprinting the conductive fiber coated with the conductive polymer using a mold having a microstructure pattern formed thereon
Method of manufacturing a fibrous sensor comprising a.
The method of claim 12,
Forming the conductive fiber made of the stretchable fiber and metal nanoparticles formed inside the stretchable fiber
The method of manufacturing a fibrous sensor comprising the step of absorbing the metal nanoparticles in the elastic fiber.
The method of claim 12,
Coating the conductive polymer
A method of manufacturing a fibrous sensor comprising flowing a conductive polymer-containing solution along a longitudinal direction of the conductive fiber.

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