KR102208377B1 - Fiber cposite and preparing method of the same - Google Patents

Abstract

The present invention is stretchable (Strechable) fiber; A conductive elastic polymer layer coated on the stretchable fiber; A polymer bead disposed on the elastic fiber or the elastic polymer layer; And It relates to a fiber composite for a strain sensor comprising a conductive elastic polymer layer coating the polymer beads and a method for manufacturing the same, by coating conductive particles, polymer beads and elastic polymers on the surface of the stretchable fiber using simple mixing and coating, It can provide excellent durability, recovery, repeatability, and strain with high sensitivity.

Description

Fiber composite and its manufacturing method {FIBER CPOSITE AND PREPARING METHOD OF THE SAME}

The present invention relates to a fiber composite and a method of manufacturing the same, and more particularly, to a fiber composite for a strain sensor.

In the wearable device market, which has recently attracted attention, research on wearable fiber sensors is being actively conducted, and studies on lifestyle care through monitoring of body motions as well as special fields such as firefighting and military use are also being conducted. Be in the spotlight. In the case of a fibrous strain sensor used in this field, it is important to maintain elasticity and sensitivity in strong strains and to have high sensitivity in small strains.

However, the conductive fiber used in the conventional fibrous strain sensor has a problem that is difficult to apply to actual clothing because it is difficult to expect flexibility and comfort. In addition, in the case of the conventional conductive fiber used in the strain sensor, there is a disadvantage in that expensive materials are used, the manufacturing cost is high, and it is not easy to manufacture in mass production, and thus the generalization of smart wear using the conventional conductive fiber is limited. Research and development have been conducted to solve these problems, but there are still difficulties in practical application. Therefore, there is a strong demand for developing a fiber implementation technology that simultaneously has low cost, use of harmless materials, high durability, and excellent sensing sensitivity.

An object of the present invention is to provide a fiber composite for a strain sensor having at the same time low cost, use of harmless materials, high durability, and excellent sensing sensitivity.

Another object of the present invention is to provide a method of manufacturing the strain sensor fiber composite.

The present invention, stretchable (Stretchable) fiber; A first conductive elastic polymer layer coated on the stretchable fiber; A polymer bead disposed on the first conductive elastic polymer layer; And it provides a fiber composite for a strain sensor comprising the polymer beads and a second conductive elastic polymer layer coating the first conductive elastic polymer layer.

The strain sensor is a sensor that detects a mechanical change of an object to be measured and detects it with an electric signal.

The polymer bead is present in a solid state by curing at least one polymer material, and has a spherical independent shape having a diameter of between 100 μm and 200 μm. However, the present invention is not necessarily limited thereto.

Elasticity means the property of an object to stretch and shrink.

In one embodiment, the first and second conductive elastic polymer layers may include conductive particles dispersed in an elastic polymer.

In one embodiment, the conductive particles may include at least one of carbon black, carbon nanotubes (CNTs), and graphene.

In one embodiment, the polymer beads may have a diameter between 100 μm and 200 μm.

In one embodiment, the polymer beads may be cured polymer beads.

In one embodiment, the first and second elastic polymers and the polymer beads are each independently of each other, natural rubber, nitrile rubber, acrylonitrile-butadiene rubber, and styrene. Butadiene rubber, chloroprene rubber, butyl rubber, isoprene-isobutylene rubber, ethylene propylene rubber, chlorosulphonated polyethylene rubber polyethylene rubber), acrylic rubber, fluoro rubber, polysulfide rubber, silicone rubber, butadiene rubber, isoprene rubber, urethane rubber (urethane rubber), polyurethane (polyurethane), PDMS (polydimethylsiloxane), polyolefin thermoplastic elaster (TPE), polystyrene TPE (polystyrene TPE), polyvinyl chloride TPE (polyvinyl chloride TPE), polyester TPE ( polyester TPE), polyurethane TPE (polyurethane TPE), and polyamide TPE (polyamide TPE).

In one embodiment, the first and second elastic polymers may be polyurethane.

In one embodiment, the polymer beads may be PDMS beads.

In one embodiment, the elastic fiber material may be a polyurethane-based fiber.

In one embodiment, the stretchable fiber is a stretchable fiber coated with polyvinyl alcohol (PVA), and the first and second conductive elastic polymer layers are polymers comprising polyurethane in which carbon black is dispersed. Layer, and the polymer beads may be PDMS beads.

The present invention, an organic solvent; An elastic polymer dissolved in the organic solvent; Polymer beads insoluble in the organic solvent; And it provides a polymer solution mixed with conductive particles, comprising coating on the surface of a stretchable fiber material, a method of manufacturing a fiber composite for a strain sensor.

The organic solvent is a liquid organic material capable of dissolving an elastic polymer.

In one embodiment, the polymer solution may further include a dispersant.

In one embodiment, the dispersant may be P3HT (poly(3-hexylthiophene)).

In one embodiment, the elastic polymer may be polyurethane.

In one embodiment, the polymer beads may be cured PDMS beads.

In one embodiment, the organic solvent may include at least one of chloroform, dimethylformamide (DMF), toluene, dimethyl sulfoxide (DMSO), and N-methylpyrrolidone (NMP).

In one embodiment, the material forming the conductive particles may include at least one of carbon black, carbon nanotubes (CNTs), and graphene.

In one embodiment, the polymer solution may be a solution of carbon black, cured PDMS beads, polyurethane, and an organic solvent.

In one embodiment, the strain fiber may be a PVA coated fiber.

The fiber composite of the present invention is manufactured through a simple manufacturing method, and a conductive material and an elastic polymer are disposed on the surface of a fiber material having elasticity or elasticity, so that it is relatively excellent in durability and conductivity and is stable. Therefore, in the case of a strain sensor manufactured using this, durability, recovery, repeatability, and sensitivity are excellent, and also exhibit a fast sensing speed.

1 is a view for explaining a fiber composite for a strain sensor of the present invention.
2 is a view for explaining a method of manufacturing a polymer bead of the present invention.
3 is a view for explaining a method of manufacturing a polymer solution of the present invention.
4 is a view for explaining a method of manufacturing a fiber composite for a strain sensor of the present invention.
5 is a view showing an SEM image for surface analysis of the strain sensor fiber composite manufactured according to an embodiment of the present invention. 5A is a view showing a surface image before applying strain to a fiber composite for a strain sensor manufactured according to an embodiment of the present invention. (b) is a diagram showing a surface image after applying strain to a fiber composite for a strain sensor manufactured according to an embodiment of the present invention. (C) is an image of a strain sensor including a fiber composite for a strain sensor manufactured according to an embodiment of the present invention.
6 is a diagram showing a graph of a response rate and resistance change according to strain of a sensor including a fiber composite for a strain sensor manufactured according to an embodiment of the present invention.
7 is a diagram showing a graph for evaluating the stability of a sensor including a fiber composite for a strain sensor manufactured according to an embodiment of the present invention.
8 is a view showing a surface image for a comparative analysis of the surface of the strain sensor fiber composite according to the PVA coating.
9 is a view showing an SEM image for comparative analysis of the surface of a fiber composite according to the presence or absence of PVA coating and the addition of PDMS. 9A and 9B are images showing the surfaces of each of the fiber composites prepared according to the presence or absence of PVA coating when the polymer beads are not included. (c) and (d) are images showing the surface of each of the fiber composites prepared according to the presence or absence of PVA coating when 5 wt% of polymer beads are included.
10 is a view showing an image of a fiber composite for a strain sensor according to whether or not PU is added.
11 is a diagram showing an optical microscope (OM) image for comparative analysis of the surface of a fiber composite with or without PU addition.
12 is a view showing an SEM image for comparative analysis of the surface of a fiber composite with or without PU addition.
13 is a view showing a graph for evaluating the mechanical properties of the strain sensor fiber composite with or without polymer beads.
14 is a view for comparing the reaction rate of a sensor manufactured using a fiber composite according to the addition ratio of the polymer beads.
15 shows surface SEM images of fiber composites prepared according to the polymer bead ratio of the present invention.
16 is a view showing a graph for evaluating the performance of the strain sensor according to the addition ratio of the polymer beads. FIG. 16A is a graph showing resistance according to strain of the strain sensor according to the addition ratio of polymer beads. (b) is a graph showing the gauge factor according to the strain of the sensor according to the addition ratio of polymer beads.
17 is a diagram for evaluating the performance of the strain sensor according to the polymer beads.
18 is a diagram for evaluating the performance of the strain sensor according to the weight of carbon black. 18A is a graph showing the conductivity of the strain sensor according to the weight of carbon black. 18B is a graph showing the stability of the strain sensor according to the weight of carbon black. 18C is a graph showing the resistance change of the strain sensor according to the weight of carbon black.
19 is a view for evaluating the performance after applying a strain of 300% of the sensor according to the addition ratio of the dispersant.
20 is a diagram showing pulse measurement of a strain sensor including a fiber composite manufactured according to an embodiment of the present invention.

The terms used in the present application are only used to describe specific embodiments and are not intended to limit the present invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In the present application, terms such as "comprise" or "have" are intended to designate the existence of features, steps, actions, components, parts, or a combination thereof described in the specification, but one or more other features or steps It is to be understood that it does not preclude the possibility of addition or presence of, operations, components, parts, or combinations thereof.

Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which the present invention belongs. Terms as defined in a commonly used dictionary should be interpreted as having a meaning consistent with the meaning in the context of the related technology, and should not be interpreted as an ideal or excessively formal meaning unless explicitly defined in this application. Does not.

The present invention relates to a fiber composite for a strain sensor and a method for manufacturing the same, and first, a fiber composite for a strain sensor manufactured according to the manufacturing method of the present invention will be described with reference to FIG. 1.

Referring to Figure 1, the fiber composite of the present invention is stretchable (Strechable) fiber; A first conductive elastic polymer layer coated on the stretchable fiber; A polymer bead disposed on the first conductive elastic polymer layer; And a second conductive elastic polymer layer coating the polymer beads and the first conductive elastic polymer.

Referring to (i) of FIG. 1, the stretchable fiber of the present invention may be a polyurethane-based fiber as a fiber having properties that can be stretched and contracted, or spandex, a synthetic fiber made of an elastic yarn of polyurethane fiber. However, the present invention is not limited thereto, and may be a fiber that can be stably restored to its original shape when stretched and contracted. In addition, the elastic fiber may be an elastic fiber coated with polyvinyl alcohol (hereinafter referred to as PVA). The coating of the PVA may be used to increase adhesion to the conductive elastic polymer layer, and specifically, the OH end group of the PVA increases the adhesion to the conductive elastic polymer layer due to hydrogen bonding with the -OH end group of the conductive particles. It can have the effect of becoming.

Referring to (ii) and (iii) of FIG. 1, it can be seen that the first conductive elastic polymer layer coated on the elastic fiber or the elastic fiber coated with PVA is present in the fiber composite of the present invention. Polymer beads are present on the first conductive elastic polymer layer, and the polymer beads may be coated with a second conductive elastic polymer layer.

The first and second conductive elastic polymer layers may include conductive particles dispersed in an elastic polymer. The conductive particles may include at least one of carbon black, carbon nanotubes, and graphene. Preferably, the conductive particles may be carbon black. When using carbon black as the conductive particles, it is preferable to add 70 wt% of carbon black. Due to the conductive particles, the fiber composite of the present invention can have excellent conductivity, which also affects the strain sensor.

The polymer beads are present in a solid state by curing at least one polymer material, and have a spherical independent shape having a diameter between 100 μm and 200 μm. Preferably, the polymer beads may be PDMS beads. However, the present invention is not necessarily limited thereto.

The fiber composite of the present invention may have an uneven surface due to the polymer beads, and when used as a strain sensor, the fiber composite of the present invention is stable without dropping of the polymer beads due to the elastic polymer layer or the elastic fiber even when the strain is changed. It can be restored to its original form. This effect can appear because the polymer beads are coated with a conductive elastic polymer layer.

A method of manufacturing a fiber composite for a strain sensor according to the present invention will be described with reference to FIGS. 2, 3 and 4.

First, the polymer beads of the present invention exist in a solid state by curing at least one polymer material, and have a spherical independent shape having a diameter between 100 μm and 200 μm. Referring to FIG. 2, (a) explaining the method of manufacturing a polymer bead of the present invention, a polymeric material emulsion is prepared by dissolving PVA in a polymeric material solution and tertiary distilled water, and using a membrane emulsification device. And, it can be prepared by curing the prepared polymer emulsion using an oven. As an additional step, the cured polymer beads may be washed with water and ethanol and then dried to prepare them. At this time, (b) referring to the micrograph of the prepared polymer beads, the polymer beads exist in the form of independent spherical particles. The polymer beads may have a diameter of 100 to 200 μm, but are not limited thereto.

Referring to FIG. 3, when the method for preparing the polymer solution of the present invention is described, first, a step of dissolving an elastic polymer in an organic solvent may be performed. The organic solvent is a liquid organic material capable of dissolving an elastic polymer and is referred to as chloroform, dimethylformamide (hereinafter referred to as DMF), toluene, and dimethyl sulfoxide (hereinafter referred to as DMSO). ) And methylpyrrolidone (NMP) may be any one selected, preferably, may be chloroform. However, it is not necessarily limited thereto. The solution in which the elastic polymer is dissolved may be further mixed with a dispersant. Then, the step of mixing and dispersing the conductive particles and the step of mixing and dispersing the polymer beads in the solution in which the conductive particles are mixed are sequentially performed to prepare the polymer solution of the present invention. In this case, the polymer beads may be present in the polymer solution while maintaining the state of the beads in the polymer solution while not being dissolved in the organic solvent.

Referring to Figure 4, using the cured polymer beads and the polymer solution prepared as described above will be described a method of manufacturing a fiber composite for a strain sensor of the present invention. The manufacturing method may include PVA coating a solution of PVA on the stretchable fiber and impregnating the PVA-coated fiber with a polymer solution. After the coating, it may further include a step of drying. In the present invention, the coating may be performed using a dip-coating method, but is not limited thereto.

Hereinafter, through specific examples and comparative examples, the fiber composite for a strain sensor of the present invention and a method of manufacturing the same will be described in more detail.

Example 1: Preparation of fiber composite for strain sensor

1-1. Preparation of polymer beads

Sylgard 184 silicone elastomer kit (Dow corning, USA) Part A and Part B were mixed at a mass percent ratio of 6:4 to prepare 4 mL of a mixed solution, and 5 wt% of PVA was added to 80 mL of tertiary distilled water. After preparing the dissolved solution, a PDMS emulsion was prepared using the mixed solution and the solution through an SPG membrane emulsification device. Put the emulsion in an oven, cure under an atmosphere of 70°C, wash the cured particles with water and ethanol, and dry them to prepare PDMS polymer beads according to Example 1(1-1) of the present invention. I did.

1-2. Preparation of polymer solution

After 0.74 g of polyurethane was added to 20 g of chloroform as an organic solvent, a solution in which the polyurethane was dissolved was prepared through sonication for 30 minutes, and P3HT (Poly(3- hexylthiophene)) was added and sonication was performed for 5 minutes to prepare an intermediate solution. After adding 1.26 g of carbon black as conductive particles to the intermediate solution and using sonication for 10 minutes, 5 wt% of the PDMS polymer beads prepared according to Example 1 above were added and sonication was performed for 10 minutes. A polymer solution according to Example 1 (1-2) of the invention was prepared.

1-3. Fabrication of fiber composites for strain sensors

After coating the spandex-in polyurethane fiber with a 1 wt% PVA solution through a dip-coating method, the PVA-coated fiber was impregnated with the polymer solution according to Example 1 (1-2) of the present invention, and then for 5 minutes. After manufacturing using sonication, a drying process was performed to prepare a fiber composite for a strain sensor according to Example 1 of the present invention.

Comparative Example 1

Except for the step of coating a 1 wt% PVA solution on the spandex-in polyurethane fiber through a dip-coating method, the same process as the fabrication of the strain sensor fiber composite according to Example 1 of the present invention was performed, and the present invention A fiber composite for a strain sensor according to Comparative Example 1 was prepared.

Comparative Example 2

In the preparation of the polymer solution, except for the addition of 0.74 g polyurethane (PU), the same process as the preparation of the fiber composite for a strain sensor according to Example 1 of the present invention was performed, and Comparative Example 2 of the present invention A fiber composite for the strain sensor was prepared according to the above.

Experimental Example 1: Surface analysis of fiber composite for strain sensor

In order to analyze the surface of the fiber composite prepared according to Example 1 of the present invention, a surface image was obtained using a SEM (Scanning Electron Microscope). Fig. 5 shows the obtained surface image.

5 is an image showing the surface of the fiber composite for a strain sensor according to Example 1 of the present invention using a scanning electron microscope (SEM).

Referring to Figure 5, (a) the surface of the fiber composite, it can be confirmed that a polymer bead and a conductive elastic polymer layer are uniformly coated on the elastic fiber on the elastic fiber, and the curved surface due to the polymer bead is confirmed. I can. (b) After applying the strain, the surface of the fiber composite can be confirmed to be stretched well without dropping of the polymer beads, and the appearance of the polymer beads separated by a distance from the surface of the fiber composite before applying the strain. (c) is a view of a strain sensor manufactured using a fiber composite. The sensor, in which an electrode is additionally attached and connected through a copper tape and a conductive paste, can electrically specify a minute strain change. 5, it can be seen that the fiber composite of the present invention is stably restored to its original shape even with a change in strain.

Experimental Example 2: Performance evaluation of strain sensor

In order to perform performance evaluation on the strain sensor including the fiber composite manufactured according to an embodiment of the present invention, a strain of 10%, 50%, 100% and 200% was applied, and the measured reaction rate and resistance change were measured. I did. The results are shown in FIG. 6.

Referring to FIG. 6, when strains of the same size are repeatedly performed on the sensor, it can be seen that the sensor exhibits a fast response speed and a sensitive resistance change.

Subsequently, in order to evaluate the stability of the strain sensor including the fiber composite manufactured according to an embodiment of the present invention, resistance was measured while repeatedly performing a strain of 20% on the sensor 5000 times, and strain through the measured resistance The stability of the sensor was evaluated. The results are shown in FIG. 7.

Referring to FIG. 7, it can be seen that even when a strain of 20% is repeatedly performed 5000 times, the sensor including the fiber composite manufactured according to an embodiment of the present invention maintains stability.

Experimental Example 3: Comparative evaluation of fiber composites for strain sensors according to PVA coating

In order to analyze the surface of the strain sensor fiber composite according to the PVA coating, using the strain sensor fiber composite prepared according to an Example and Comparative Example 1 of the present invention, after applying a strain of 100% to each of the fiber composite Each surface image was obtained when it was restored to its original state. The image was obtained using OM (Optical Microscope) (Olympus BX51, Olympus, Japan), and the results are shown in FIG. 8.

Referring to FIG. 8, in the case of the fiber composite manufactured without PVA coating treatment, it can be seen that the surface of the fiber composite is not smooth and foreign substances have fallen off the surface. On the other hand, in the case of the fiber composite prepared by PVA coating treatment, it can be seen that the surface has a smooth surface. Through this, it can be expected that the PVA coating has an effect of improving adhesion so that the elastic polymer layer can be well maintained on the stretchable fiber.

In order to check the adhesion with the conductive elastic polymer layer according to the previously described PVA coating in more detail, a fiber composite for strain sensor according to the presence or absence of PVA coating and PDMS was prepared, and after applying strain to each fiber composite, it returned to its original state. When turned, an image of the surface of each fiber composite was obtained using a SEM (Scanning Electron Microscope). The results are shown in FIG. 9.

Referring to Figure 9 (a) and (b), comparing the surface of the fiber composite without PDMS according to the presence or absence of PVA coating, in the case of the fiber composite manufactured without the PVA coating treatment of (a), elasticity It can be seen that the elastic polymer layer coated on the fiber was not maintained and fell, and the surface of the fiber composite was uneven. On the other hand, in the case of the fiber composite manufactured by the PVA coating treatment of (b), it can be seen that the coating is well maintained with a smooth surface, so that the elastic polymer layer is stably present on the surface. Through this, it can be seen that the PVA coating exhibits an effect that the elastic polymer layer can be well maintained on the elastic fiber regardless of the presence or absence of the polymer beads.

Referring to (c) and (d) of Figure 9, comparing the surface of the fiber composite containing 5 wt% PDMS according to the presence or absence of PVA coating, (c) of the fiber composite prepared without the PVA coating treatment In this case, it can be confirmed that the polymer beads are partially separated on the elastic fiber, and the conductive elastic polymer layer is also partially separated on the elastic fiber. On the other hand, (d) in the case of the fiber composite manufactured by PVA coating treatment, it can be seen that the polymer beads are stably fixed on the PVA-coated elastic fiber, and the conductive elastic polymer layer is also stably on the PVA-coated elastic fiber. You can check the fixed appearance.

Accordingly, it can be seen that the PVA coating in the present invention not only improves adhesion so that the elastic polymer layer is well maintained on the stretchable fiber, but also has the effect of allowing the polymer bead to be well adhered to the stretchable fiber.

Experimental Example 4: Comparative evaluation of fiber composites for strain sensors according to polyurethane (PU)

In order to compare the fiber composite for a strain sensor with or without polyurethane, the fiber composite for a strain sensor prepared according to an Example and Comparative Example 2 of the present invention was compared and analyzed. The comparative analysis will be described with reference to FIG. 10.

Referring to Figure 10, in the case of the fiber composite (left) that does not contain polyurethane according to Comparative Example 2, it can be seen that black particles are separated around the fiber composite, which is actually carbon when the fiber composite is held by hand. It can be seen that the elastic polymer layer is unstable due to the black staining on the hand. On the other hand, in the case of the fiber composite containing polyurethane (right), it can be seen that the coating is well done without the appearance of particles falling around the fiber composite. 10, in the case of manufacturing a fiber composite without polyurethane, it can be expected that the polyurethane serves to hold the carbon black and PDMS polymer beads.

Subsequently, in order to compare the surfaces of the fiber composites for strain sensors prepared according to an Example and Comparative Example 2 of the present invention, the surface of each fiber composite was measured with an OM (Optical Microscope) (Olympus BX51, Olympus, Japan). And the results are shown in FIG. 11.

Referring to FIG. 11, it can be seen that all surfaces according to the presence or absence of polyurethane have a smooth appearance.

Accordingly, for a more detailed surface analysis, surface images of the fiber composite for strain sensors prepared according to an Example and Comparative Example 2 of the present invention were obtained using a SEM (Scanning Electron Microscope), and the results are shown in 12.

Referring to FIG. 12, first, when analyzing the surface of the fiber composite for strain sensor prepared according to Comparative Example 2, the fiber composite (PU 30%) containing polyurethane has a conductive elastic polymer layer in a net form due to polyurethane. It can be seen that the polymer beads PDMS and carbon black are fixed so that they do not fall off the surface. In comparison, it can be seen that the surface of the fiber composite that does not contain polyurethane (PU 0%) cannot fix the carbon black and PDMS polymer beads, and the surface is very unstable. Through this, it can be expected that the polyurethane plays a role of helping to form the conductive elastic polymer layer in the form of a net, thereby fixing PDMS and carbon black.

Experimental Example 5: Evaluation of fiber composite for strain sensor and sensor performance according to polymer beads

First, evaluation of the fiber composite for a strain sensor and a sensor including the same according to the presence or absence of polymer beads was performed. PDMS was used as the polymer beads.

In order to evaluate the strain sensor fiber composite with or without polymer beads, the stress according to the strain applied to the strain sensor fiber composite fabricated with or without PDMS was measured. The results are shown in FIG. 13.

Referring to FIG. 13, compared to the fiber composite without PDMS, it can be seen that the graph of the fiber composite containing PDMS shows a similar appearance.Through this, even if the polymer bead particles are included, the mechanical properties of the conventional fiber composite It can be seen that it is maintained without inhibiting.

In addition, performance evaluation was performed by measuring the sensitivity of the strain sensor prepared using the fiber composite according to the presence or absence of polymer beads. The results are shown in Fig. 14.

Referring to FIG. 14, it can be seen that the strain sensor (red) including PDMS has a sensor sensitivity that is up to 13 times higher than that of the strain sensor (black) that does not include PDMS. Through this, it can be seen that the strain sensor manufactured using the fiber composite to which the polymer beads are added has high sensitivity.

Subsequently, the fiber composite prepared according to the ratio of the polymer beads of the present invention and the sensor including the same were evaluated. The polymer beads used in the above evaluation were PDMS, and the results are shown in FIGS. 15 to 17.

15 shows SEM images of fiber composites prepared according to the polymer bead ratio of the present invention.

Referring to FIG. 15, it can be seen that the polymer beads are separated from each other on the surface of the fiber composite to which 1 wt% and 3 wt% of PDMS are added, and the surface to which the polymer beads are not attached exists. Compared with 1 wt% of PDMS, it can be seen that the surface of the fiber composite to which 3 wt% of PDMS is added has more polymer beads attached to each other.

On the other hand, in the case of the surface of the fiber composite to which 5 wt% of PDMS is added, polymer beads are attached to most of the surface of the fiber composite, and it can be seen that the polymer beads are very close to each other. In addition, it can be seen that the surface to which the polymer beads are not attached is hardly visible.

Likewise, in the case of the surface of the fiber composite to which 7 wt% and 10 wt% of PDMS were added, polymer beads were attached to most of the surface of the fiber composite, and it was confirmed that the polymer beads were very closely attached to each other. I can.

Referring to FIGS. 16A and 16B, in the case of a strain sensor including 0 wt% PDMS and a strain sensor including 1 wt% PDMS, changes in resistance and gauge factor according to strain are You can see that there are few. On the other hand, in the case of a strain sensor including 3 wt% PDMS and a strain sensor including 5 wt% PDMS, it can be seen that the resistance and gauge factor change as the strain increases, and 3 wt% PDMS is Compared with the included strain sensor, it can be seen that the strain sensor including 5 wt% PDMS has a greater change in resistance and gauge factor according to strain.

Through this, it can be confirmed that the sensitivity of the strain sensor increases as the ratio of the added PDMS increases, and it can be confirmed that the sensitivity of the sensor to which 5 wt% of PDMS is added is the highest.

In addition, referring to FIG. 17, when comparing a sensor to which 5 wt% of PDMS is added and a sensor to which 0 wt% of PDMS is added, a sensor to which 5 wt% of PDMS is added exhibits a more sensitive reaction in the same strain. You can see what it represents.

Experimental Example 6: Evaluation of the performance of the strain sensor according to the conductive particles

In an embodiment of the present invention, a fiber composite for a strain sensor having a different weight% (wt%) to which carbon black is added by using carbon black as a conductive particle was prepared, and the strain sensor including the prepared fiber composite Conductivity, stability and resistance were measured to perform the above performance evaluation, and the results are shown in FIG. 18.

Referring to (a) of FIG. 18, in the case of the strain sensor to which 20, 40, and 60 wt% of carbon black is added, it can be seen that the conductivity slightly changes. On the other hand, in the case of the strain sensor to which 70 and 80 wt% of carbon black is added, it can be seen that the conductivity is greatly increased. Through this, when 60 wt% or more of carbon black is added, it can be expected to have high conductivity characteristics and to affect the performance of the strain sensor due to this result.

Referring to (b) of FIG. 18, compared to the strain sensor to which 20, 40, and 60 wt% of carbon black is added, the strain sensor to which 70 and 80 wt% of carbon black is added changes the gauge rate according to the strain. You can see that is large. When comparing the strain sensor to which 70 and 80 wt% of carbon black is added, it can be seen that the change in the gauge ratio of the strain sensor to which 80 wt% of carbon black is added is larger. Through this, it can be seen that when 80 wt% of carbon black is used, stability is rapidly deteriorated.

Referring to FIG. 18C, in the case of the strain sensor to which 80 wt% of carbon black was added, it can be seen that a change in resistance did not appear in a strain of about 90% or more. In the case of the strain sensor to which 20 and 40 wt% of carbon black was added, it can be seen that the change in resistance was smaller than that of the case where 60 and 70 wt% of carbon black were added.

As a result, it can be seen that in the case of a sensor manufactured using 70 wt% of carbon black as conductive particles, the stability and conductivity of the sensor, that is, the stability and sensitivity of the sensor, are simultaneously excellent.

Experimental Example 7: Evaluation of sensor performance according to dispersant

In an embodiment of the present invention, a fiber composite having a different weight% (wt%) to which P3HT is added was prepared using P3HT as a dispersant, and a strain sensor was manufactured using the prepared fiber composite. After applying a strain of 300% to the manufactured strain sensor, performance evaluation of the sensor according to Experimental Example 3 of the present invention was performed through the analysis of the relative resistance when it was returned to its original state. The results are shown in Fig. 19.

Referring to FIG. 19, it can be seen that the sensor (red) containing 5 wt% of P3HT exhibits the best recovery. Therefore, when using P3HT as a dispersing agent, it may be preferable to add 3 to 7 wt%. More preferably, it can be prepared by adding 5 wt% of P3HT, and it can be expected that the sensor manufactured as described above can exhibit the best performance.

Experimental Example 8: Application of Strain Sensor

A strain sensor using a fiber composite manufactured according to an embodiment of the present invention was attached to a person's arm and connected to an analysis device to measure the pulse rate. The results are shown in FIG. 20.

Referring to FIG. 20, the strain sensor can sensitively sense the pulse rate of a patient with "low blood pressure", "normal" and "high blood pressure", so it is expected that there is a possibility that the strain sensor can be applied and used in the medical field. I can.

Although the above has been described with reference to preferred embodiments of the present invention, those skilled in the art will be able to variously modify and change the present invention without departing from the spirit and scope of the present invention described in the following claims. You will understand that you can.

Claims (19)

Stretchable fibers;
A first conductive elastic polymer layer coated on the stretchable fiber;
A polymer bead disposed on the first conductive elastic polymer layer; And
Comprising a second conductive elastic polymer layer coating the polymer beads and the first conductive elastic polymer layer,
Fiber composite for strain sensors. The method of claim 1,
The first and second conductive elastic polymer layers are characterized in that conductive particles are dispersed in the elastic polymer,
Fiber composite for strain sensors. The method of claim 2,
The conductive particle is characterized in that it comprises at least one or more of carbon black (carbon black), carbon nano tube (Carbon Nano Tube, CNT) and graphene (Graphene),
Fiber composite for strain sensors. The method of claim 1,
The polymer bead, characterized in that having a diameter between 100㎛ 200㎛,
Fiber composite for strain sensors. The method of claim 1,
The polymer beads are characterized in that the cured polymer beads,
Fiber composite for strain sensors. The method of claim 2,
The first and second elastic polymers and the polymer beads are each independently of each other, natural rubber, nitrile rubber, acrylonitrile-butadiene rubber, and styrene butadiene rubber. ), chloroprene rubber, butyl rubber, isoprene-isobutylene rubber, ethylene propylene rubber, chlorosulphonated polyethylene rubber, acrylic Acrylic rubber, fluoro rubber, polysulfide rubber, silicone rubber, butadiene rubber, isoprene rubber, urethane rubber, Polyurethane, PDMS (polydimethylsiloxane), polyolefin thermoplastic elaster (TPE), polystyrene TPE (polystyrene TPE), polyvinyl chloride TPE (polyvinyl chloride TPE), polyester TPE (polyester TPE), poly It characterized in that it comprises at least one or more of urethane TPE (polyurethane TPE) and polyamide TPE (polyamide TPE),
Fiber composite for strain sensors. The method of claim 1,
The first and second elastic polymers are polyurethane, characterized in that,
Fiber composite for strain sensors. The method of claim 1,
The polymer beads are characterized in that the beads of PDMS,
Fiber composite for strain sensors. The method of claim 1,
The elastic fiber material is characterized in that the polyurethane-based fiber,
Fiber composite for strain sensors. The method of claim 7,
The stretchable fiber is an elastic fiber coated with polyvinyl alcohol (PVA),
The first and second conductive elastic polymer layers are polymer layers including polyurethane in which carbon black is dispersed,
The polymer beads are characterized in that the beads of PDMS,
Fiber composite for strain sensors. Organic solvent; An elastic polymer dissolved in the organic solvent; Polymer beads insoluble in the organic solvent; And a polymer solution in which conductive particles are mixed, comprising coating on the surface of a stretchable fiber material,
A method of manufacturing a fiber composite for strain sensors. The method of claim 11,
The polymer solution further comprises a dispersant,
A method of manufacturing a fiber composite for strain sensors. The method of claim 12,
The dispersant is characterized in that P3HT (poly(3-hexylthiophene)),
A method of manufacturing a fiber composite for strain sensors. The method of claim 11,
The elastic polymer is characterized in that the polyurethane,
A method of manufacturing a fiber composite for strain sensors. The method of claim 11,
The polymer beads are characterized in that the cured PDMS beads,
A method of manufacturing a fiber composite for strain sensors. The method of claim 11,
The organic solvent comprises at least one or more of chloroform, dimethylformamide (DMF), toluene, dimethyl sulfoxide (DMSO), and N-methylpyrrolidone (NMP),
A method of manufacturing a fiber composite for strain sensors. The method of claim 11,
The material of the conductive particle is characterized in that it contains at least one or more of carbon black, carbon nano tube (CNT), and graphene,
A method of manufacturing a fiber composite for strain sensors. The method of claim 11,
The polymer solution is characterized in that it is a solution of carbon black, cured PDMS beads, polyurethane and organic solvent,
A method of manufacturing a fiber composite for strain sensors. The method of claim 18,
The strain fiber is characterized in that the PVA coated fiber,
A method of manufacturing a fiber composite for strain sensors.

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