KR102739933B1 - Fiber type strain sensor with metal nanobelt/nanocarbon material hybrid materials, and fabrication method - Google Patents

Abstract

The present invention relates to a fiber-type strain sensor including a composite of a metal nanobelt and a carbon nanomaterial, and a method for manufacturing the same, the technical gist of which comprises: a step of modifying the surface of a carbon nanomaterial to introduce a functional group into the conductive carbon nanomaterial; a step of reacting the surface-modified carbon nanomaterial by mixing an isocyanate-based compound and a pyrimidine-based compound to form a carbon nanomaterial dispersion reactive with metal ions; a step of adding a metal salt precursor and a solvent to the carbon nanomaterial dispersion, and adding a reducing agent while controlling the addition speed thereof, to form a metal nanobelt on the surface of the carbon nanomaterial; a step of mixing a composite composed of a carbon nanomaterial-metal nanobelt with a polymer to manufacture a conductive fiber; and a step of implementing a fiber-type strain sensor using the conductive fiber. By this, the conductivity of the conductive fiber is increased by synthesizing the metal nanobelt with which surface contact is made, and since the metal nanobelt is synthesized on the surface of the carbon nanomaterial, the contact between the carbon nanomaterial and the metal nanobelt is excellent, and a fiber-type strain sensor including a composite of the metal nanobelt and carbon nanomaterial with excellent dispersion in an evenly dispersed state can be obtained. In addition, when the metal nanobelt with which surface contact is made is tensilely deformed, the distance between the metal nanobelts aligned in the fiber direction increases, so that an effect applicable to a strain sensor can be obtained by the principle that the resistance rapidly increases.

Description

{Fiber type strain sensor with metal nanobelt/nanocarbon material hybrid materials, and fabrication method}

The present invention relates to a fiber-type strain sensor including a metal nanobelt and a carbon nanomaterial composite, and a method for manufacturing the same, and more specifically, to a fiber-type strain sensor including a metal nanobelt and a carbon nanomaterial composite having excellent dispersibility in an evenly dispersed state, and a method for manufacturing the same, in which the conductivity of a conductive fiber is increased by synthesizing a metal nanobelt that makes surface contact, and since the metal nanobelt is synthesized on the surface of the carbon nanomaterial, the contact between the carbon nanomaterial and the metal nanobelt is excellent, and the metal nanobelt and carbon nanomaterial composite have excellent dispersibility.

Recently, as safety accidents involving machines, tools, and structures have been occurring frequently, interest in safety has increased. In the case of machines, tools, and structures, since they are often used in harsh conditions such as high and low temperatures, they must be sturdy enough to not deform, and lightweight is required for economic efficiency and performance. In order to satisfy these contradictory conditions, more advanced design technology for machines, tools, and structures is required. Accordingly, a method can be applied to prevent safety accidents by measuring changes in numerical values through a detection device that measures the physical quantities of machines, tools, and structures. A strain sensor can be used as the detection device.

A strain sensor is a sensor that converts a minute mechanical change (strain) into an electrical signal and detects it. When such a strain sensor is attached to a machine, tool, or structure, it is possible to measure the minute numerical change, or strain, that occurs on the surface, and from the numerical change, the stress, which is important for confirming strength or stability, can be determined. Accordingly, strain sensors are widely used in large structures such as automobiles, aircraft, bridges, and dams, and are not only used as sensor elements to convert physical quantities such as force, pressure, acceleration, displacement, and torque into electrical signals, but are also widely used for experiments, research, and measurement control.

Strain sensors according to the prior art are manufactured using materials such as PDMS, rubber, polyurethane, elastic fiber, and ecoflex, as in 'Korean Patent Office Registration Patent No. 10-1500840, Manufacturing Method of Strain Sensor, Strain Sensor, and Motion Detection Device Using Strain Sensor'. A strain sensor measures surface deformation of a subject to be measured according to changes in the resistance value of a resistance element, and in general, the resistance value has a property of increasing when the strain sensor is stretched by an external force and decreasing when the strain sensor is compressed.

However, when a material according to the conventional technology is applied to a strain sensor, it can be confirmed that there is not much change in resistance as the conductivity decrease value is small even when a tensile strain of about 10% occurs as shown in Fig. 1. In other words, when a material according to the conventional technology is applied to a strain sensor, there is a problem in that the conventional strain sensor cannot be applied to an area where it can detect a minute strain because the change in resistance is not large even when the tensile strain is large.

Korean Intellectual Property Office Registered Patent No. 10-1500840

Accordingly, the purpose of the present invention is to provide a fiber-type strain sensor including a composite of a carbon nanomaterial and a metal nanobelt having excellent dispersion in an evenly dispersed state, and a method for manufacturing the same, which increases the conductivity of a conductive fiber by synthesizing a metal nanobelt with which surface contact is made, and has excellent contact between the carbon nanomaterial and the metal nanobelt because the metal nanobelt is synthesized on the surface of the carbon nanomaterial.

In addition, the present invention provides a fiber-type strain sensor including a composite of a metal nanobelt and a carbon nanomaterial that can be applied to a strain sensor and a method for manufacturing the same, based on the principle that when a metal nanobelt that makes surface contact is subjected to tensile deformation, the distance between the metal nanobelts aligned in the fiber direction increases, rapidly increasing resistance.

The above object is achieved by a method for manufacturing a fiber-type strain sensor including a composite of a metal nanobelt and a carbon nanomaterial, characterized by including a step of modifying the surface of a carbon nanomaterial to introduce a functional group into the conductive carbon nanomaterial; a step of forming a carbon nanomaterial dispersion reactive with metal ions by mixing and reacting an isocyanate-based compound and a pyrimidine-based compound with the surface-modified carbon nanomaterial; a step of adding a metal salt precursor and a solvent to the carbon nanomaterial dispersion, and adding the mixture while controlling the addition speed of a reducing agent to form a metal nanobelt on the surface of the carbon nanomaterial; a step of manufacturing a conductive fiber by mixing a composite composed of the carbon nanomaterial-metal nanobelt with a polymer; and a step of implementing a fiber-type strain sensor using the conductive fiber.

Here, in the step of forming the metal nanobelt, the addition speed of the reducing agent is preferably 0.1 to 5 ml/min based on 100 ml of the reaction solution.

The step of manufacturing the conductive fiber comprises: mixing the complex with the polymer and then dispersing it using a paste mixer to manufacture a paste for conductive fiber; and manufacturing the conductive fiber using the conductive fiber paste through a solution spinning process; and it is preferable that the complex is contained in an amount of 1 to 50 parts by weight among 100 parts by weight of the polymer and the complex in the conductive fiber paste.

The above carbon nanomaterial is selected from the group consisting of carbon nanotubes (CNT), carbon fibers, graphene, carbon black, and mixtures thereof, and the isocyanate compound is selected from the group consisting of ethylene diisocyanate, 1,4-tetramethylene diisocyanate, 1,6-hexamethylene diisocyanate (HDI), 1,12-dodecane diisocyanate, cyclobutane-1,3-diisocyanate, cyclohexane-1,3-diisocyanate, cyclohexane-1,4-diisocyanate, 1-isocyanato-3,3,5-trimethyl-5-isocyanatomethyl-cyclohexane, 2,4-hexahydrotoluene diisocyanate, 2,6-hexahydrotoluene diisocyanate, hexahydrotoluene diisocyanate, Ro-1,3-Phenylene diisocyanate, Hexahydro-1,4-Phenylene diisocyanate, Perhydro-2,4'-Diphenylmethane diisocyanate, Perhydro-4,4'-Diphenylmethane diisocyanate, 1,3-Phenylene diisocyanate, 1,4-Phenylene diisocyanate, 1,4-Durol diisocyanate (DDI), 4,4'-Stilbene diisocyanate, 3,3'-Dimethyl-4,4'-Biphenylene diisocyanate (TODI), Toluene 2,4-Diisocyanate, Toluene 2,6-Diisocyanate (TDI), Diphenylmethane-2,4'-Diisocyanate (MDI), 2,2'-Diphenylmethane diisocyanate (MDI), Diphenylmethane-4,4'-Diisocyanate (MDI) and naphthylene-1,5-isocyanate (NDI), 2,2-methylenediphenyl diisocyanate, 5,7-diisocyanatonaphthalene-1,4-dione, isophorone diisocyanate, m-xylene diisocyanate, 3,3-dimethoxy-4,4-biphenylene diisocyanate, 3,3-dimethoxybenzidine-4,4-diisocyanate, poly(propylene glycol) having a toluene 2,4-diisocyanate terminal group, poly(ethylene glycol) having a toluene 2,4-diisocyanate terminal group, triphenylmethane triisocyanate, diphenylmethane triisocyanate, butane-1,2,2-triisocyanate, trimethylolpropantoylene didisocyanate trimer, 2,4,4-diphenyl ether triisocyanate, and many It is preferably selected from the group consisting of isocyanurates having hexamethylene diisocyanate, iminooxadiazines having multiple hexamethylene diisocyanates, polymethylenepolyphenyl isocyanates, and mixtures thereof.

In addition, the pyrimidine compound is selected from the group consisting of 2-amino-6-methyl-1H-pyrido[2,3-d]pyrimidin-4-one, 2-amino-6-bromopyrido[2,3-d]pyridin-4(3H)-one, 2-amino-4-hydroxy-5-pyrimidinecarbonic acid ethyl ester, 2-amino-6-ethyl-4-hydroxypyrimidine, 2-amino-4-hydroxy-6-methyl pyrimidine, 2-amino-5,6-dimethyl-4-hydroxypyrimidine, and mixtures thereof, and the metal salt precursor is selected from the group consisting of a gold (Au) salt precursor, a silver (Ag) salt precursor, a platinum (Pt) salt precursor, a copper (Cu) salt precursor, an aluminum (Al) salt precursor, a palladium (Pd) salt precursor, and a nickel (Ni) salt. It is preferred to be selected from the group consisting of precursors and mixtures thereof.

The reducing agent is preferably selected from the group consisting of sodium hydroxide (NaOH), potassium hydroxide (KOH), ammonium hydroxide (NH ₄ OH), sodium borohydride (NaBH ₄ ), hydrazine (N ₂ H ₄ ), hydriodine (HI), ascorbic acid, a reducing organic solvent, and mixtures thereof.

The above object is also achieved by a fiber-type strain sensor including a metal nanobelt and carbon nanomaterial composite, characterized in that the composite includes a conductive fiber formed by mixing an isocyanate-based compound and a pyrimidine-based compound with a surface-modified carbon nanomaterial and reacting them to form a carbon nanomaterial dispersion reactive with metal ions, adding a metal salt precursor and a solvent to the carbon nanomaterial dispersion, and controlling the addition rate of a reducing agent to form a metal nanobelt on the surface of the carbon nanomaterial, and mixing the composite formed of the carbon nanomaterial-metal nanobelt with a polymer.

Here, the metal nanobelt is formed in a ribbon shape to enable area contact, and it is preferable that the conductive fiber has a resistance change of 300% or more according to tensile strain.

According to the configuration of the present invention described above, the conductivity of the conductive fiber is increased by synthesizing the metal nanobelt with which surface contact is made, and since the metal nanobelt is synthesized on the surface of the carbon nanomaterial, the contact between the carbon nanomaterial and the metal nanobelt is excellent, and a fiber-type strain sensor including a composite of the metal nanobelt and the carbon nanomaterial with excellent dispersion in an evenly dispersed state can be obtained.

In addition, an effect applicable to a strain sensor can be obtained by the principle that when a metal nanobelt that is in contact with the surface is subjected to tensile deformation, the distance between the metal nanobelts aligned in the fiber direction increases, causing a rapid increase in resistance.

Figure 1 is a graph showing the resistance according to tensile deformation of a fiber for a strain sensor according to the prior art.
FIG. 2 is a perspective view of a conductive fiber included in a fiber-type strain sensor according to an embodiment of the present invention;
Figure 3 is a flow chart of a method for manufacturing a fiber-type strain sensor according to an embodiment of the present invention.
Figure 4 is a SEM image of a carbon nanotube-silver nanobelt composite.
Figure 5 is an SEM image of the conductive fiber.
Figures 6 and 7 are graphs showing the resistance according to the tensile change of the strain sensor.

Hereinafter, a fiber-type strain sensor including a metal nanobelt and a carbon nanomaterial composite according to an embodiment of the present invention and a manufacturing method thereof will be described in detail with reference to the drawings. Herein, the metal nanobelt means a ribbon-shaped structure that enables area contact. The fiber-type strain sensor is composed of a configuration including a conductive fiber, and the conductive fiber is formed by reacting an isocyanate-based compound and a pyrimidine-based compound with a surface-modified carbon nanomaterial to form a carbon nanomaterial dispersion that is reactive with metal ions, adding a metal salt precursor and a solvent to the carbon nanomaterial dispersion, controlling the addition speed of a reducing agent to form a metal nanobelt on the surface of the carbon nanomaterial, and mixing the composite formed of the carbon nanomaterial-metal nanobelt with a polymer. As illustrated in FIG. 2, the following manufacturing process is performed to manufacture the fiber-type strain sensor of the present invention.

As shown in Fig. 3, first, the carbon nanomaterial is surface modified (S1).

Carbon nanomaterials are surface-modified to introduce functional groups that react with metal precursors into the carbon nanomaterials. The step of surface-modifying the carbon nanomaterials uses different methods depending on the type of carbon nanomaterial. Here, the carbon nanomaterials are selected from the group consisting of graphene, carbon nanotubes (CNTs), carbon fibers, carbon black, and mixtures thereof.

A carbon nanomaterial dispersion that is reactive with metal ions is formed (S2).

A carbon nanomaterial dispersion reactive with metal ions is formed by mixing and reacting an isocyanate compound and a pyrimidine compound with a surface-modified carbon nanomaterial. Here, the method for forming the carbon nanomaterial dispersion is as follows: the carbon nanomaterial is dispersed in a solvent, then mixed with an isocyanate compound, and heated and stirred to introduce an isocyanate group into the carbon nanomaterial. A pyrimidine compound is added thereto, and then heated and stirred to perform a bonding reaction, thereby forming a carbon nanomaterial dispersion reactive with metal ions.

Here, the isocyanate compounds are ethylene diisocyanate, 1,4-tetramethylene diisocyanate, 1,6-hexamethylene diisocyanate (HDI), 1,12-dodecane diisocyanate, cyclobutane-1,3-diisocyanate, cyclohexane-1,3-diisocyanate, cyclohexane-1,4-diisocyanate, 1-isocyanato-3,3,5-trimethyl-5-isocyanatomethyl-cyclohexane, 2,4-hexahydrotoluene diisocyanate, 2,6-hexahydrotoluene diisocyanate, hexahydro-1,3-phenylene diisocyanate, hexahydro-1,4-phenylene diisocyanate, perhydro-2,4'-diphenylmethane diisocyanate, Perhydro-4,4'-diphenylmethane diisocyanate, 1,3-phenylene diisocyanate, 1,4-phenylene diisocyanate, 1,4-durol diisocyanate (DDI), 4,4'-stilbene diisocyanate, 3,3'-dimethyl-4,4'-biphenylene diisocyanate (TODI), toluene 2,4-diisocyanate, toluene 2,6-diisocyanate (TDI), diphenylmethane-2,4'-diisocyanate (MDI), 2,2'-diphenylmethane diisocyanate (MDI), diphenylmethane-4,4'-diisocyanate (MDI) and naphthylene-1,5-isocyanate (NDI), 2,2-methylenediphenyl diisocyanate, 5,7-diisocyanatonaphthalene-1,4-dione, isophorone diisocyanate, m-xylene diisocyanate, 3,3-dimethoxy-4,4-biphenylene diisocyanate, 3,3-dimethoxybenzidine-4,4-diisocyanate, poly(propylene glycol) having a toluene 2,4-diisocyanate terminal group, poly(ethylene glycol) having a toluene 2,4-diisocyanate terminal group, triphenylmethane triisocyanate, diphenylmethane triisocyanate, butane-1,2,2-triisocyanate, trimethylolpropantoylene didisocyanate trimer, 2,4,4-diphenyl ether triisocyanate, isocyanurate having multiple hexamethylene diisocyanates, multiple hexamethylene diisocyanates It is preferred that the genie is selected from the group consisting of iminooxadiazine, polymethylenepolyphenyl isocyanate and mixtures thereof.

In addition, the pyrimidine compound is preferably selected from the group consisting of 2-amino-6-methyl-1H-pyrido[2,3-d]pyrimidin-4-one, 2-amino-6-bromopyrido[2,3-d]pyridin-4(3H)-one, 2-amino-4-hydroxy-5-pyrimidinecarbonic acid ethyl ester, 2-amino-6-ethyl-4-hydroxypyrimidine, 2-amino-4-hydroxy-6-methyl pyrimidine, 2-amino-5,6-dimethyl-4-hydroxypyrimidine, and mixtures thereof.

It is preferable that the carbon nanomaterial be contained in an amount of 0.001 to 10 parts by weight per 100 parts by weight of the dispersion. However, if the carbon nanomaterial is contained in an amount of less than 0.001 parts by weight, the content of the carbon nanomaterial is too small to obtain nanometal particles of uniform diameter, and if it exceeds 10 parts by weight, the amount of the carbon nanomaterial is too large compared to the rate at which the nanometal particles are formed, making it difficult to apply the composite to various purposes.

Metal nanobelts are manufactured from a carbon nanomaterial dispersion (S3).

A metal nanobelt is manufactured by adding a metal salt precursor, a reducing agent, and a solvent to a carbon nanomaterial dispersion. Here, the metal nanobelt can be applied without limitation as long as it can be manufactured using a precursor such as gold (Au), silver (Ag), platinum (Pt), copper (Cu), aluminum (Al), palladium (Pd), nickel (Ni), etc.

At this time, when adding the metal salt precursor and solvent to the carbon nanomaterial dispersion, it is not important, but when adding the reducing agent, the addition speed is very important, so the reducing agent is added while controlling the addition speed. When the reducing agent is added at a fast speed, the reactivity between the carbon nanomaterial and the metal salt precursor increases, resulting in a metal in the shape of a round particle.

That is, metal particles, not belt shapes, are formed on the surface of the carbon nanomaterial. Therefore, it is important to control the speed of the reducing agent to obtain metal nanobelts, not metal particles. It is preferable that the addition speed of the reducing agent be 0.1 to 5 ml/min. If the addition speed is less than 0.1 ml/min, the manufacturing time is long and the productivity is low, and if it exceeds 5 ml/min, the reactivity between the carbon nanomaterial and the metal salt precursor increases, which causes a problem of obtaining metal particles, not metal nanobelt shapes. Therefore, the addition speed of the reducing agent to synthesize metal nanobelts on the surface of the carbon nanomaterial is most preferably 0.1 to 5 ml/min.

Here, the silver precursor for producing the silver nanometal particles is preferably selected from the group consisting of silver nitrate (AgNO ₃ ), silver perchlorate (AgClO 4 ), silver tetrafluoroborate (AgBF ₄ ), silver hexafluorophosphate (AgPF ₆ ), _silver acetate (CH ₃ COOAg), silver trifluoromethanesulfonate (AgCF ₃ SO ₃ ), silver sulfate (Ag ₂ SO ₄ ), silver 2,4-pentanedionate (CH ₃ COCH=COCH ₃ Ag) and mixtures thereof.

In addition, the platinum precursor for producing platinum nanometal particles is preferably selected from the group consisting of chlorotetraamineplatinum (Pt(NH ₃ )4Cl ₂ ), dichlorotetraamineplatinum hydrate (Pt(NH ₃ ) ₄ Cl ₂ ·xH ₂ O), tetraamineplatinum hydroxide hydrate (Pt(NH ₃ ) ₄ (OH) ₂ ·xH ₂ O), tetraamineplatinum(II) nitrate (Pt(NH ₃ ) ₄ (NO ₃ ) ₂ ), bis-ethylenediamineplatinum(II) chloride ((H ₂ NCH ₂ CH ₂ NH ₂ ) ₂ PtCl ₂ ), chloroplatinic acid ([H ₃ O] ₂ [PtCl ₆ ](H ₂ O)x or H ₂ PtCl ₆ ), and mixtures thereof.

The reducing agent is preferably selected from the group consisting of sodium hydroxide (NaOH), potassium hydroxide (KOH), ammonium hydroxide (NH ₄ OH), sodium borohydride (NaBH ₄ ), hydrazine (N ₂ H ₄ ), hydriodine (HI), ascorbic acid, a reducing organic solvent, and mixtures thereof.

Afterwards, the metal nanobelt containing carbon nanomaterial is separated from the reducing agent, solvent, and residual metal precursor involved in the reaction to obtain a pure product.

Conductive fibers are manufactured using a metal nanobelt and carbon nanomaterial composite (S4).

In order to manufacture a conductive fiber, a polymer for conductive fiber is prepared, a metal nanobelt-carbon nanomaterial composite is mixed with the polymer, and then dispersed using a paste mixer to manufacture a paste for conductive fiber. At this time, it is preferable that the metal nanobelt-carbon nanomaterial composite is contained in an amount of 1 to 50 parts by weight among 100 parts by weight of the entire polymer and composite of the conductive fiber paste. If the metal nanobelt-carbon nanomaterial composite is less than 1 part by weight, the composites do not properly contact each other within the fiber-type strain sensor, resulting in low conductivity. If it exceeds 50 parts by weight, the amount of the composite is large compared to the polymer, resulting in a problem that the conductive fiber is not flexible and breaks. In addition, if it exceeds 50 parts by weight, there is also a disadvantage that it is difficult to pull it out in the form of a fiber. The conductive fiber paste manufactured in this way is used to form a conductive fiber through a solution spinning process.

In some cases, conductive fibers can be manufactured by separately adding one of the group consisting of graphene, carbon nanotubes (CNTs), carbon fibers, carbon black, and mixtures thereof, which are carbon nanomaterials, to the conductive fiber paste. When the carbon nanomaterials are mixed into the conductive fiber paste in this manner and the paste is solution-spun, the solvent present in the paste solidifies as it moves toward the surface during the solidification process in the coagulation bath for solution spinning. Accordingly, since the metal nanobelts in the paste have an affinity for the solvent, they move to the surface along with the solvent, and the central region of the fiber is filled with the separately mixed carbon nanomaterial. As a result, the carbon nanomaterial-metal nanobelt complex with excellent conductivity is induced to concentrate on the surface of the fiber, and as a result, the conductive fiber exhibits excellent electrical conductivity.

A fiber-type strain sensor is implemented using conductive fibers (S5).

The conductive fiber obtained through step S4 is used as a flexible electrode, and metal wires are fixed to both ends of the flexible electrode using metal paste. For example, after fixing a copper wire using silver paste, a strain sensor is implemented through a molding process so that the metal paste does not fall off using a polymer. However, this configuration and structure are only one example of a strain sensor, and a strain sensor can be implemented without limitation in various configurations and structures including the conductive fiber of the present invention.

Below, embodiments of the present invention are described in more detail.

<Example 1>

In Example 1 of the present invention, first, 5 g of multi-walled carbon nanotubes used as carbon nanomaterials are mixed in 100 ml of a 60% nitric acid solution, heated to 100°C, stirred for 24 hours, and then cooled to room temperature. Thereafter, 400 ml of distilled water is added to dilute the solution. The diluted solution is filtered at least four times using filter paper to remove the nitric acid solution remaining in the carbon nanotubes, and then dried to produce multi-walled carbon nanotubes to which carboxyl groups (-COOH) have been introduced. The carbon nanotubes to which carboxyl groups have been introduced are dispersed at 100 mg/L in a dimethylformamide (DMF) solvent, and then toluene diisocyanate is mixed and stirred at 100°C for 12 hours to introduce isocyanate groups.

Next, 2-ureido-4[1H]pyrimidinone groups are introduced to the surface and ends of carbon nanotubes by mixing 2-amino-4-hydroxy-6-methyl-pyrimidine with the carbon nanotubes to which an isocyanate group has been introduced and stirring at 100°C for 20 hours to carry out a bonding reaction. The carbon nanotubes with the functional groups thus manufactured are dispersed in a dimethylformamide solvent at 0.1 g/L, and silver nitrate (AgNO ₃ ) is added at 0.1 mol/L to prepare a silver salt mixture.

Hydrazine as a reducing agent was added to the prepared silver salt mixture at a rate of 0.2 ml per minute at room temperature and stirred to slowly reduce the reaction rate, thereby forming a nanobelt structure. Silver nanobelts complexed with carbon nanotubes in the prepared reaction solution were obtained as shown in Fig. 4 by removing the solvent using centrifugation or filtering.

In order to manufacture a conductive fiber using the manufactured carbon nanotube-silver nanobelt composite material, first, 10 wt% of polyurethane is dissolved in dimethylformamide to manufacture a basic dope for fiber, and the carbon nanotube-silver nanobelt composite material is dispersed therein using a paste mixer to an amount of 10 to 30 wt% based on the total volume of the fiber to manufacture a conductive fiber paste having a solid content of 15 wt%. Next, the carbon nanotube-silver nanobelt/polyurethane paste is solidified by spinning it into a methanol coagulation bath through a syringe nozzle using a quantitative pump, and then dried by heat at 70°C to obtain a conductive fiber. The conductive fiber manufactured in this manner can be confirmed through the SEM image of Fig. 5. Fig. 5a is a low-magnification image of the conductive fiber, and Fig. 5b is a high-magnification image of the conductive fiber. Through Fig. 5b, it can be confirmed that a silver nanobelt exists in the conductive fiber of the present invention.

As a result of measuring the electrical conductivity of the conductive fiber, it was confirmed that excellent electrical conductivity of 1000 S/cm or more was shown when the carbon nanotube-silver nanobelt composite material was contained at 20 wt%. As shown in Fig. 6, the conductive fiber of the manufactured strain sensor was connected to a finger, and the resistance change according to the bending of the finger was measured. As a result, the resistance change showed excellent sensitivity of 300% or more even at a tensile strain of 5% or less of the conductive fiber. This showed excellent strain sensor characteristics with a gauge constant (GF) value of approximately 60, which is a key factor of the strain sensor. In addition, as the strain increased, the resistance change rate increased rapidly, and even when it changed by more than 10,000 times and then was restored, the resistance lowered back to the original state, showing excellent resilience. Fig. 7 is a graph that confirms the resistance change rate according to the conductive fiber of the strain sensor. It can be confirmed that as the tensile strain increases, the resistance change also increases sensitively. When the conductive fiber is returned to its original state, the resistance decreases again. Therefore, it can be seen that the conductive fiber included in the strain sensor of the present invention is very sensitive to the resistance change according to the tensile strain.

In the case of strain sensors made of materials such as PDMS, rubber, polyurethane, elastic fiber, and ecoflex, when the strain sensor is subjected to tensile strain, the resistance actually decreases because the particles of the material become closer in the direction perpendicular to the direction in which the tensile strain occurs. However, in the case of the strain sensor of the present invention, the resistance increases rapidly due to the principle that the distance between the nanobelts aligned in the fiber direction increases when tensile strain occurs. In addition, when such a strain sensor is applied to machines, tools, and structures, or when utilized as a fabric-type wearable sensor or attached to the human body, it can easily detect minute changes.

Claims (12)

A method for manufacturing a fiber-type strain sensor comprising a metal nanobelt and a carbon nanomaterial composite,
A step of modifying the surface of a carbon nanomaterial to introduce a functional group into the conductive carbon nanomaterial;
A step of forming a carbon nanomaterial dispersion that is reactive with metal ions by mixing and reacting an isocyanate compound and a pyrimidine compound with the surface-modified carbon nanomaterial;
A step of adding a metal salt precursor and a solvent to the carbon nanomaterial dispersion, and adding a reducing agent while controlling the addition speed, thereby forming a metal nanobelt on the surface of the carbon nanomaterial;
A step of manufacturing a conductive fiber by mixing a composite composed of carbon nanomaterial and metal nanobelt with a polymer;
A step of implementing a fiber-type strain sensor using the above conductive fiber,
A method for manufacturing a fiber-type strain sensor including a metal nanobelt and a carbon nanomaterial composite, characterized in that in the step of forming the metal nanobelt, the addition speed of the reducing agent is 0.1 to 5 ml/min based on 100 ml of the reaction solution.
delete In paragraph 1,
The step of manufacturing the above conductive fiber is:
A method for manufacturing a fiber-type strain sensor including a metal nanobelt and carbon nanomaterial composite, characterized in that the above-mentioned composite is mixed with the above-mentioned polymer and dispersed using a paste mixer to manufacture a paste for conductive fibers, and the above-mentioned conductive fiber paste is used to manufacture a conductive fiber through a solution spinning process. In the third paragraph,
A method for manufacturing a fiber-type strain sensor including a metal nanobelt and a carbon nanomaterial composite, characterized in that the composite is contained in an amount of 1 to 50 parts by weight out of 100 parts by weight of the entire polymer and the composite in the conductive fiber paste. In paragraph 1,
The above carbon nanomaterials are,
A method for manufacturing a fiber-type strain sensor comprising a metal nanobelt and a carbon nanomaterial composite, characterized in that the metal nanobelt is selected from the group consisting of carbon nanotubes (CNTs), carbon fibers, graphene, carbon black, and mixtures thereof. In paragraph 1,
The above isocyanate compound is,
Ethylene diisocyanate, 1,4-tetramethylene diisocyanate, 1,6-hexamethylene diisocyanate (HDI), 1,12-dodecane diisocyanate, cyclobutane-1,3-diisocyanate, cyclohexane-1,3-diisocyanate, cyclohexane-1,4-diisocyanate, 1-isocyanato-3,3,5-trimethyl-5-isocyanatomethyl-cyclohexane, 2,4-hexahydrotoluene diisocyanate, 2,6-hexahydrotoluene diisocyanate, hexahydro-1,3-phenylene diisocyanate, hexahydro-1,4-phenylene diisocyanate, perhydro-2,4'-diphenylmethane diisocyanate, Perhydro-4,4'-diphenylmethane diisocyanate, 1,3-phenylene diisocyanate, 1,4-phenylene diisocyanate, 1,4-durol diisocyanate (DDI), 4,4'-stilbene diisocyanate, 3,3'-dimethyl-4,4'-biphenylene diisocyanate (TODI), toluene 2,4-diisocyanate, toluene 2,6-diisocyanate (TDI), diphenylmethane-2,4'-diisocyanate (MDI), 2,2'-diphenylmethane diisocyanate (MDI), diphenylmethane-4,4'-diisocyanate (MDI) and naphthylene-1,5-isocyanate (NDI), 2,2-methylenediphenyl diisocyanate, 5,7-diisocyanatonaphthalene-1,4-dione, isophorone diisocyanate, m-xylene diisocyanate, 3,3-dimethoxy-4,4-biphenylene diisocyanate, 3,3-dimethoxybenzidine-4,4-diisocyanate, poly(propylene glycol) having a toluene 2,4-diisocyanate terminal group, poly(ethylene glycol) having a toluene 2,4-diisocyanate terminal group, triphenylmethane triisocyanate, diphenylmethane triisocyanate, butane-1,2,2-triisocyanate, trimethylolpropantoylene didisocyanate trimer, 2,4,4-diphenyl ether triisocyanate, isocyanurate having multiple hexamethylene diisocyanates, multiple hexamethylene diisocyanates A method for manufacturing a fiber-type strain sensor comprising a metal nanobelt and a carbon nanomaterial composite, characterized in that the metal nanobelt is selected from the group consisting of iminooxadiazine, polymethylenepolyphenyl isocyanate, and mixtures thereof. In paragraph 1,
The above pyrimidine compound is,
A method for manufacturing a fiber-type strain sensor including a metal nanobelt and a carbon nanomaterial composite, characterized in that the metal nanobelt is selected from the group consisting of 2-amino-6-methyl-1H-pyrido[2,3-d]pyrimidin-4-one, 2-amino-6-bromopyrido[2,3-d]pyridin-4(3H)-one, 2-amino-4-hydroxy-5-pyrimidinecarbonic acid ethyl ester, 2-amino-6-ethyl-4-hydroxypyrimidine, 2-amino-4-hydroxy-6-methyl pyrimidine, 2-amino-5,6-dimethyl-4-hydroxypyrimidine, and mixtures thereof. In paragraph 1,
The above metal salt precursor is,
A method for manufacturing a fiber-type strain sensor including a metal nanobelt and a carbon nanomaterial composite, characterized in that the metal nanobelt is selected from the group consisting of a gold (Au) salt precursor, a silver (Ag) salt precursor, a platinum (Pt) salt precursor, a copper (Cu) salt precursor, an aluminum (Al) salt precursor, a palladium (Pd) salt precursor, a nickel (Ni) salt precursor, and mixtures thereof. In paragraph 1,
The above reducing agent is,
A method for manufacturing a fiber-type strain sensor including a metal nanobelt and a carbon nanomaterial composite, characterized in that the metal nanobelt is selected from the group consisting of sodium hydroxide (NaOH), potassium hydroxide (KOH), ammonium hydroxide (NH ₄ OH), sodium borohydride (NaBH ₄ ), hydrazine (N ₂ H ₄ ), hydriodine (HI), ascorbic acid, a reducing organic solvent, and mixtures thereof. In a fiber-type strain sensor including a metal nanobelt and a carbon nanomaterial composite,
A fiber-type strain sensor including a metal nanobelt and a carbon nanomaterial composite, characterized in that the composite includes a conductive fiber formed by mixing an isocyanate compound and a pyrimidine compound with a surface-modified carbon nanomaterial and reacting the mixture to form a carbon nanomaterial dispersion reactive with metal ions, adding a metal salt precursor and a solvent to the carbon nanomaterial dispersion, and controlling the addition speed of a reducing agent to form a metal nanobelt in a ribbon shape so as to enable area contact with the surface of the carbon nanomaterial, and mixing the composite formed of the carbon nanomaterial-metal nanobelt with a polymer.
delete In Article 10,
A fiber-type strain sensor including a metal nanobelt and carbon nanomaterial composite, characterized in that the conductive fiber has a resistance change of 300% or more according to tensile strain.

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