KR20190083947A - Adhesive transparent electrode and method for manufacturing thereof - Google Patents

Abstract

The present invention relates to an adhesive transparent electrode and a manufacturing method thereof. According to one embodiment of the present invention, the adhesive transparent electrode comprises a substrate and an adhesive polydimethylsiloxane (PDMS) matrix in which a silver (Ag) nanowire network deposited on the substrate is embedded. The adhesive polydimethylsiloxane matrix contains polydimethylsiloxane containing polydimethylsiloxane base and polydimethylsiloxane curing agents, and non-ionic surfactants. The present invention uses non-ionic surfactants to easily control physical properties of polydimethylsiloxane only by a very small amount of non-ionic surfactant.

Description

TECHNICAL FIELD [0001] The present invention relates to an adhesive transparent electrode,

The present invention relates to a sticky transparent electrode and a method of manufacturing the same, and more particularly to a sticky transparent electrode in which a silver nanowire network is embedded in a sticky polydimethylsiloxane (PDMS) matrix containing a nonionic surfactant to improve conformability and stickiness, And a method for producing the same.

In recent years, attention and research on wearable electronic devices have been increasing due to the development of Internet (IoT) and interest in well-being ().

Particularly, in the case of a biosensor which is attached to the body to sense the movement of the body or to detect a bio-signal, it is very important to develop a sticky electrode material because it must adhere well to the body. In addition, in the case of a biosensor using an electric signal, a process of forming an electrode on a substrate is required. By reducing such an additional process, the cost of the process can be greatly reduced.

On the other hand, there have been reported techniques for mixing polydimethylsiloxane with an additive to control the physical properties of polydimethylsiloxane so as to have adhesiveness and high ductility. The most reported method is the use of silicone-based additives similar to polydimethylsiloxane. However, when an additive of silicone type is used, an excessive amount of additive is required, and the viscosity of the solution is increased by the additive, which causes difficulty in solution process.

In recent years, studies have been made to control the physical properties of polydimethylsiloxane so as to have adhesiveness and high ductility by using an amine-based polymer such as ethoxylated polyethyleneimine (PEIE). However, when ethoxylated polyethyleneamine is used, residues remain on the surface during separation after bonding, and light transmittance is reduced due to internal moisture because of high hygroscopicity.

In addition, all of the above-mentioned methods for changing the physical properties of the polydimethylsiloxane are a study for changing only the physical properties of the polydimethylsiloxane material. In order to form electrodes for manufacturing electronic devices, electrodes are formed through coating or vapor deposition processes .

Therefore, even with a small amount of additives, the physical properties of the polydimethylsiloxane can be easily controlled, the permeability difference compared to the conventional polydimethylsiloxane is not large, and the viscosity of the liquid before curing is not high.

Embodiments of the present invention are to provide a sticky transparent electrode which can easily control the physical properties of polydimethylsiloxane even with a very small amount of nonionic surfactant by using a nonionic surfactant and a method for producing the same.

Embodiments of the present invention are to provide a sticky transparent electrode capable of sticking to skin without additional adhesive due to its high tackiness of transparent electrode according to an embodiment of the present invention, and maintaining stickiness even after detachment and attachment, and a method for manufacturing the same.

Embodiments of the present invention provide a sticky transparent electrode capable of forming a transparent electrode simultaneously with the curing of polydimethylsiloxane and a method of manufacturing the same, unlike the conventional method of forming an electrode through a coating process or the like on a cured polymer substrate I want to.

Embodiments of the present invention aim to provide a sticky transparent electrode capable of maintaining electrical conductivity even at a high elongation due to the electrical characteristics of the nanowire network and a method for manufacturing the same.

A tacky transparent electrode according to an embodiment of the present invention comprises a substrate and a tacky polydimethylsiloxane matrix embedded with a silver (Ag) nanowire network deposited thereon, the tacky polydimethylsiloxane matrix comprising a polydimethylsiloxane matrix base and a polydimethylsiloxane curing agent and a nonionic surfactant.

The viscous transparent electrode according to the embodiment of the present invention may be used in the crosslinking reaction of the polydimethylsiloxane due to the interaction of the Pt functional group present in the polydimethylsiloxane curing agent and the polar functional group present in the nonionic surfactant. ) Can be hindered and the mechanical properties of the adhesive polydimethylsiloxane matrix can be improved.

The tacky transparent electrode according to an embodiment of the present invention is characterized in that the interaction between the polar functional groups present in the nonionic surfactant and the polar functional groups present in the silver nanowire network causes the silver nanowire network to bind to the tacky polydimethylsiloxane matrix Can be embedded.

In the viscous transparent electrode according to the embodiment of the present invention, the nonionic surfactant may be 4- (1,1,3,3-tetramethylbutyl) phenyl-polyethylene glycol.

The viscous transparent electrode according to an embodiment of the present invention may have a weight ratio of the polydimethylsiloxane subject, the polydimethylsiloxane curing agent, and the nonionic surfactant in a weight ratio of 10: 1: 0.01 to 10: 1: 0.08.

A method of manufacturing a tacky transparent electrode according to an embodiment of the present invention includes forming a silver nanowire network on a substrate, forming on the substrate having the silver nanowire network a polydimethylsiloxane subject, a polydimethylsiloxane curing agent and a nonionic interface Coating a dispersion comprising an active agent and thermally curing the dispersion coated on the substrate on which the silver nanowire network has been formed to form an adhesive polydimethylsiloxane matrix having the silver nanowire network embedded therein.

The method of manufacturing a tacky transparent electrode according to an embodiment of the present invention may further comprise separating the adhesive polydimethylsiloxane matrix from which the silver nanowire network is embedded.

In the method of manufacturing a sticky transparent electrode according to an embodiment of the present invention, the step of forming a nanowire network on the substrate includes: coating a silver nanowire solution on the substrate; And annealing the substrate coated with the silver nanowire solution.

In the method of manufacturing a sticky transparent electrode according to an embodiment of the present invention, the substrate coated with the silver nanowire solution may be annealed at 100 ° C to 180 ° C for 5 minutes to 20 minutes.

In the method of manufacturing a sticky transparent electrode according to an embodiment of the present invention, the dispersion coated on the substrate on which the silver nanowire network is formed can be thermally cured at 40 ° C to 80 ° C.

According to an embodiment of the present invention, by using a nonionic surfactant, the physical properties of the polydimethylsiloxane can be easily controlled with only a very small amount of nonionic surfactant.

In addition, according to the embodiment of the present invention, the transparent electrode according to the embodiment of the present invention has high adhesiveness, so that it can be attached to the skin without additional adhesive, and the adhesive property can be maintained even after detachment.

In addition, according to the embodiment of the present invention, unlike the conventional method of forming an electrode through a coating treatment or the like on a cured polymer substrate, a transparent electrode can be produced simultaneously with thermosetting of polydimethylsiloxane.

Further, according to the embodiment of the present invention, electrical conductivity can be maintained even at a high elongation due to the electrical characteristics of the silver nanowire network.

1 is a view illustrating a method of manufacturing a sticky transparent electrode according to an embodiment of the present invention.
Figures 2a-2e illustrate images of a tacky polydimethylsiloxane matrix according to the Triton x-100 content in a tacky polydimethylsiloxane matrix according to an embodiment of the present invention, Figure 2f show images of Triton x-100 in an adhesive polydimethylsiloxane matrix, 100 in terms of light transmittance.
3a is a graph showing the stress-strain curves of the adhesive polydimethylsiloxane matrix according to an embodiment of the present invention, and Fig. 3b is a graph showing the stress-strain curves of the adhesive polydimethylsiloxane matrix during the uniaxial stretching test of a4-PDMS_40 FIG.
Figure 4 is a graph showing the viscoelasticities of a tacky polydimethylsiloxane matrix according to an embodiment of the present invention.
5A is a graph showing an adhesion force measured by a peel test of a sticky polydimethylsiloxane matrix according to an embodiment of the present invention, and FIGS. 5B to 5H are graphs showing the adhesion force measured by a peel test ≪ / RTI > and Figure 5i shows an image of a tacky polydimethylsiloxane matrix supporting various weights.
FIGS. 6A and 6B are graphs showing swelling ratios of the adhesive polydimethylsiloxane matrix according to an embodiment of the present invention, and FIGS. 6C and 6D are graphs showing gel fractions. FIG.
FIGS. 7A and 7B are graphs showing the cell viability and optical microscopic images of fibroblasts for measuring the biocompatibility of the adhesive polydimethylsiloxane matrix according to an embodiment of the present invention, and FIG. 7C is a graph showing the absorbance FIG.
FIG. 8 is a graph showing the light transmittance of a sticky transparent polydimethylsiloxane matrix-based adhesive electrode in which silver nanowires are embedded according to an embodiment of the present invention.
9A is a graph showing a result of performing a stretch test to evaluate the elasticity of a sticky polydimethylsiloxane matrix-based viscous transparent electrode embedded with silver nanowires according to an embodiment of the present invention, and Figs. 9B to 9E are graphs And a field emission-scanning electron microscopy (FE-SEM) image before and after stretching.
FIG. 10A is a photograph showing a case where a strain sensor using a transparent polydimethylsiloxane matrix-based transparent electrode (a4-PDMS_40NW) embedded with silver nanowires according to an embodiment of the present invention is attached to the wrist, and FIG. (PDMS_40NW) based on polydimethylsiloxane matrix embedded silver nanowires according to an embodiment of the present invention is attached to the wrist. FIG. 10C shows a transparent electrode (a4-PDMS_40NW) based on a sticky polydimethylsiloxane matrix embedded with silver nanowires according to an embodiment of the present invention and a polydimethylsiloxane matrix-based sticky transparent electrode (PDMS_40NW) embedded silver nanowires And the relative resistance change of the applied strain sensor.
11A to 11C are cross-sectional views of a transparent electrode (a4-PDMS_40NW) based on a sticky polydimethylsiloxane matrix embedded with silver nanowires according to an embodiment of the present invention and a polydimethylsiloxane matrix-based sticky transparent electrode PDMS_40NW) is attached to the arm, and FIG. 11D is a graph showing the skin impedance measured using the ECG sensor.
12A shows electrode positions of an ECG sensor using a transparent polydimethylsiloxane matrix-based transparent electrode (a4-PDMS_40NW) embedded with silver nanowires according to an embodiment of the present invention, and FIGS. 12B to 12E show electrode positions Of the electrocardiogram signal.
FIGS. 13A to 13D show electrode positions of an ECG sensor to which a transparent polydimethylsiloxane matrix-based transparent electrode (a4-PDMS_40NW) embedded with silver nanowires according to an embodiment of the present invention is applied, and FIGS. 13B to 13D Is a graph showing an electrocardiogram signal measured by an ECG sensor.

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

The terminology used herein is for the purpose of illustrating embodiments and is not intended to be limiting of the present invention.

As used herein, the terms "comprises", "having", or "having" are used to specify that a feature, a number, a step, an operation, an element, a component, But do not preclude the presence or addition of one or more other features, numbers, steps, operations, components, parts, or combinations thereof.

It should also be understood that the terms "an embodiment," "an embodiment, a side," "an example ", and the like used in the specification are intended to mean that any aspect or design described is better or advantageous over other aspects or designs. It does not have to be interpreted.

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

Also, the phrase "a" or " an "as used herein should be interpreted to mean" one or more ", unless the context clearly dictates otherwise do.

It will also be understood that when an element such as a film, layer, region, element, or the like is referred to as being "on" or "on" another element, , And a case where a component or the like is interposed.

Furthermore, although the 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 may be named for the purpose of distinguishing one element from another, for example without departing from the scope of the right according to the concept of the present invention, the first element being referred to as the second element, Similarly, the second component may also be referred to as the first component.

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 this invention belongs. Terms such as those defined in a commonly used dictionary should be construed as having a meaning consistent with the meaning in the context of the relevant art and are to be interpreted as ideal or overly formal in the sense of the art unless explicitly defined herein Do not.

Hereinafter, specific embodiments of the present invention will be described in detail with reference to the drawings. However, the spirit of the present invention is not limited to such embodiments, and the spirit of the present invention may be proposed differently by adding, modifying and deleting constituent elements constituting the embodiment, .

The present invention relates to a sticky transparent electrode and a method for producing the same, and relates to a transparent electrode having excellent ductility and adhesion by adding an additive (nonionic surfactant) to polydimethylsiloxane and a method for producing the same.

1 is a view illustrating a method of manufacturing a sticky transparent electrode according to an embodiment of the present invention.

Referring to FIG. 1, a sticky transparent electrode according to an embodiment of the present invention can be manufactured using a substrate, a polydimethylsiloxane, a nonionic surfactant, and a silver nanowire network.

The silver nanowire network 120 may be formed on the substrate 110 by coating the silver nanowire solution 120 on the substrate 110 and then annealing 140a.

The substrate 110 may include a transparent material capable of transmitting light, for example, but not limited to, a silicon substrate, a glass substrate, or a polymer substrate.

The silicon substrate may comprise a single silicon substrate or a p-Si substrate, and the glass substrate may be made of any one or a combination of alkali silicate glass, non-alkali glass, and quartz glass, And can be made of various materials.

The polymer substrate may be formed of any one or combination of polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyimide (PI), and polyurethane, But are not limited thereto, and can be made of various materials. However, the polymer substrate is not necessarily limited thereto as long as it has transparency and flexibility enough to be used in a transparent flexible display.

The nanowire solution 120 may be coated on the substrate by a spin coating method, but the present invention is not limited thereto. The nanowire solution 120 may have different rotation speeds and times, have.

Specifically, a method such as spin coating, spray coating, inkjet coating, slit coating, or deep coating may be used. However, But is not limited to.

The silver nanowire solution 120 is coated on the substrate 110 by spin coating at 400 rpm to 1000 rpm for 30 seconds to 60 seconds (130a), and annealing 140a is performed to evaporate and dry the solvent.

Specifically, the silver nanowire network 150 can be formed by annealing at 100 ° C to 180 ° C for 5 minutes to 20 minutes.

The silver nanowire network 150 is then coated on the coated substrate 110 with a dispersion 160 comprising a polydimethylsiloxane base, a polydimethylsiloxane cross-linker, and a nonionic surfactant .

The dispersion 160 can be prepared by mixing the polydimethylsiloxane base, the polydimethylsiloxane curing agent and the nonionic surfactant in a weight ratio of 10: 1: 0.01 to 10: 1: 0.08, preferably 10: 1: 0.03 to 10 : 1: 0.05 by weight.

The polydimethylsiloxane base may be a commercial product and may be represented by the following formula (1).

[Chemical Formula 1]

The polydimethylsiloxane curing agent may be a substance represented by the following formula (2).

(2)

Nonionic surfactants include 4- (1,1,3,3-tetramethylbutyl) phenyl-polyethylene glycol (4- (1,1,3,3-Tetramethylbutyl) phenyl-polyethylene glycol), fatty alcohol-polyoxyethylene But are not limited to, fatty alcohol-polyoxyethylene ether, polyoxyethylene sorbitan fatty acid esters, polyoxyethylene fatty acid esters, polyoxyethylene alkylether, sorbitan esters, sorbitan esters, glyceryl esters, glyceryl monostearate, polyethylene glycol, polypropylene glycol, polypropylene glycol esters, cetyl alcohol, alcohol, cetostearyl alcohol, stearyl alcohol, or a combination thereof. But is not limited thereto, and can be made of various materials.

Preferably, the nonionic surfactant is 4- (1,1,3,3-tetramethylbutyl) phenyl-polyethylene glycol [4- (1,1,3,3-Tetramethylbutyl) phenyl- polyethylene glycol].

(3)

The dispersion 160 can degas the composition through degassing and can control the physical properties of the dispersion 160 through the nonionic surfactant contained in the dispersion 160.

The dispersion 160 may be coated on the substrate 110 coated with the silver nanowire network 150 by a spin coating method and is not limited thereto and may have a different rotation speed and time , Other known coating methods may be used.

Specifically, a method such as spin coating, spray coating, inkjet coating, slit coating, or deep coating may be used. However, But is not limited to.

The dispersion 160 is coated on the substrate 110 coated with the nanowire network 150 by spin coating at 3 rpm to 400 rpm for 15 seconds to 30 seconds and then thermally cured 140b do.

Specifically, it may be thermally cured at 40 ° C. to 80 ° C. for 9 hours to 11 hours to form an adhesive polydimethylsiloxane matrix 170 embedded with a silver nanowire network 150.

Thereafter, when the thermosetting adhesive polydimethylsiloxane matrix 170 is removed from the substrate 110, a transparent transparent electrode 100 having a nanowire network embedded therein is formed.

The adhesive transparent electrode based on the adhesive polydimethylsiloxane matrix according to the embodiment of the present invention is different from the conventional method in which electrodes are formed on the thermosetting polymer substrate through other coating treatment or the like, Subsequent to separation from the substrate, the silver nanowire network is present on the surface of the polydimethylsiloxane matrix, so that it can be formed simply without any additional process to form the electrically conductive material.

Hereinafter, the characteristics of the adhesive polydimethylsiloxane matrix and the adhesive transparent electrode based on the adhesive polydimethylsiloxane matrix according to an embodiment of the present invention will be described.

(Example)

(Preparation of Dispersion)

The dispersion was prepared by mixing 10 g of a polydimethylsiloxane subject, a polydimethylsiloxane curing agent and 4- (1,1,3,3-tetramethylbutyl) phenyl-polyethylene glycol (hereinafter referred to as Triton x-100) : 1: 0 to 10: 1: 0.08.

The weight ratio of the polydimethylsiloxane base and the polydimethylsiloxane curing agent was fixed at 10: 1.

(Production of sticky transparent electrode)

The slide glass (Paul Marienfeld GmbH & Co. KG, Germany) to be used as a substrate was sequentially washed in an ultrasonic treatment bath for 10 minutes using acetone, 2-propanol and deionized water, and then dried using an air gun.

0.65 wt% silver nanowire solution (Novarials) having an average length of 30 nm and a diameter of 30 nm was spin-coated on the substrate for 60 seconds at 500 rpm and then annealed at 100 DEG C for 5 minutes to evaporate the solvent .

The dispersion was spin-coated on a substrate coated with the silver nanowire solution at 300 rpm for 15 seconds and then thermally cured at a temperature of 40 to 80 캜 for 11 hours.

The cured adhesive polydimethylsiloxane matrix was then immersed in a deionized water bath for 5 minutes at room temperature and then immersed in deionized water to remove sticky transparent electrodes from which the silver nanowire network was embedded from the substrate.

(Comparative Example)

(Preparation of Dispersion)

The dispersion was prepared by mixing polydimethylsiloxane themes, polydimethylsiloxane curing agent in a weight ratio of 10: 1.

(Preparation of transparent electrode)

The slide glass (Paul Marienfeld GmbH & Co. KG, Germany) to be used as a substrate was sequentially washed in an ultrasonic treatment bath for 10 minutes using acetone, 2-propanol and deionized water, and then dried using an air gun.

0.65 wt% silver nanowire solution (Novarials) having an average length of 30 nm and a diameter of 30 nm was spin-coated on the substrate for 60 seconds at 500 rpm and then annealed at 100 DEG C for 5 minutes to evaporate the solvent .

The dispersion was spin-coated on a substrate coated with the silver nanowire solution at 300 rpm for 15 seconds and then thermally cured at a temperature of 40 to 80 캜 for 11 hours.

The thermoset polydimethylsiloxane matrix was then immersed in a deionized water bath for 5 minutes at room temperature and then the polydimethylsiloxane matrix embedded in the silver nanowire network was removed from the substrate while immersed in deionized water.

In order to characterize the adhesive polydimethylsiloxane matrix according to an embodiment of the present invention, the weight% and the curing temperature (T _c ) of Triton x-100 in the adhesive polydimethylsiloxane matrix were varied, 1].

Sample name Weight% (%) of Triton x-100 in the adhesive polydimethylsiloxane matrix Thermal curing temperature (T _c ) ( ^o C) PDMS_40
0 40 PDMS_70 70 a3-PDMS_40
0.3 40 a3-PDMS_50 50 a3-PDMS_70 70 a4-PDMS_40
0.4 40 a4-PDMS_50 50 a4-PDMS_70 70 a5-PDMS_40 0.5 40 a8-PDMS_40 0.8 40

Figures 2a-2e illustrate images of a tacky polydimethylsiloxane matrix according to the Triton x-100 content in a tacky polydimethylsiloxane matrix according to an embodiment of the present invention, Figure 2f show images of Triton x-100 in an adhesive polydimethylsiloxane matrix, 100 in terms of light transmittance.

2A to 2E, the content of triton x-100 in the adhesive polydimethylsiloxane matrix was increased to 0%, 0.3%, 0.4%, 0.5%, and 0.8%, respectively, when the thermal curing temperature was 40 ° C, As the content of Triton x-100 increases, the light scattering of the adhesive polydimethylsiloxane matrix becomes worse.

Referring to FIG. 2F, it can be seen that as the content of Triton x-100 increases, the light transmittance (T) of the adhesive polydimethylsiloxane matrix decreases and the heat curing temperature (T _c ) can be almost neglected.

The polydimethylsiloxane matrix (PDMS_40) without Triton x-100 blend has the highest light transmittance value at a wavelength of 550 nm of 94.3%. The light transmittance of the adhesive polydimethylsiloxane matrix in which 0.3 wt% of Triton x-100 (hereinafter referred to as a3-PDMS_40) and 0.4 wt% of Triton x-100 (hereinafter referred to as a4-PDMS_40) 91.4% and 84.7%, respectively, which is lower than that of PDMS_40.

In order to produce a transparent electrode based on a sticky polydimethylsiloxane matrix, the adhesive polydimethylsiloxane matrix should have a light transmittance of 80% or more. Therefore, a3-PDMS_40 and a4-PDMS_40 were selected for further analysis.

The reason that the light transmittance decreases as the content of Triton x-100 increases is due to light scattering due to the micelle structure formed in the polydimethylsiloxane matrix mixed with Triton x-100. Since the polydimethylsiloxane matrix is very hydrophobic, the alkyl of the Triton x-100 chain forms a shell while the corresponding polyethylene glycol (PEG) moiety forms a core of a micelle structure do.

It is also known that the light scattering intensity increases as the size of the micelles increases as the concentration of the surfactant increases.

3a is a graph showing the stress-strain curves of the adhesive polydimethylsiloxane matrix according to an embodiment of the present invention, and Fig. 3b is a graph showing the stress-strain curves of the adhesive polydimethylsiloxane matrix during the uniaxial stretching test of a4-PDMS_40 FIG.

The Young's modulus and failure strain of the polydimethylsiloxane matrix and the adhesive polydimethylsiloxane matrix were 0.3 wt% Triton x prepared by varying the thermal curing temperature at 40 ° C, 50 ° C and 70 ° C, respectively -100 and 0.4% by weight of Triton x-100.

Also, the tensile speed was fixed at 1 mm · sec ^-1 , the temperature was maintained at 20 ° C, and the Young's modulus was calculated from 0% to 100% strain.

Samples for measuring the Young's modulus and fracture strain of the polydimethylsiloxane matrix and the adhesive polydimethylsiloxane matrix and their measurement results are shown in Table 2 below.

Sample Young's modulus (kPa) Breaking strain (%) PDMS_40 480 ± 30 230 a3-PDMS_40 38 ± 6.3 > 400 a4-PDMS_40 40 ± 5 > 400 a3-PDMS_50 194 ± 7.2 > 300 a4-PDMS_50 162 ± 20 > 300 a3-PDMS_70 1000 ± 50 220 a4-PDMS_70 810 ± 20 210

3A and Table 2, a3-PDMS_40 and a4-PDMS_40 indicate the lowest zero coefficient and the largest rupture strain among all the samples.

The Young's modulus and fracture strain of PDMS_40 were 500 kPa and 230%, respectively. In contrast, the coefficients of a3-PDMS_40 and a4-PDMS_40 were 38 kPa and 40 kPa, respectively, .

The coefficients of a3-PDMS_40 and a4-PDMS_40 were much lower than those of human skin, 500 kPa to 1 MPa, indicating that a3-PDMS_40 and a4-PDMS_40 are suitable for epidermal electronics .

As the Young's modulus of the polymer matrix decreases, the conformability of the electrode increases. When the adhesive polydimethylsiloxane matrix has a lower Young's modulus than the skin, the contact area between the electrode and the skin expands and the user becomes uncomfortable Can feel less.

Also, referring to FIG. 3A, it can be seen that the Young's modulus increases with increasing thermosetting temperature of the adhesive polydimethylsiloxane matrix. Conventionally, the modulus of elasticity of the polydimethylsiloxane is lowered by reducing the amount of the polydimethylsiloxane curing agent, but there is a disadvantage that the fracture strain of the polydimethylsiloxane is also lowered.

In contrast, a3-PDMS_40 and a4-PDMS_40 show highly reinforced breaking strains from which a3-PDMS_40 and a4-PDMS_40 are candidates for application as transparent and stretchable polymer matrix of epidermal electrons .

Referring to FIG. 3B, it can be seen that a4-PDMS_40 does not break even when the strain is more than 400%.

 Figure 4 is a graph showing the viscoelasticities of a tacky polydimethylsiloxane matrix according to an embodiment of the present invention.

The viscoelastic properties of the polydimethylsiloxane matrix and the adhesive polydimethylsiloxane matrix were measured using a dynamic mechanical analyzer. The viscoelasticity of the polydimethylsiloxane matrix and the adhesive polydimethylsiloxane matrix is defined by the following equation (1).

tan? is the loss tangent, E 'is the elasticity of the elastomer, and E' is the viscoelasticity of the elastomer. Thus, the elastomer exhibits higher viscoelastic behavior with higher loss tangent (tan?).

For reference, a3-PDMS_40 and a4-PDMS_40 showed similar results in the uniaxial tensile test, so only the viscoelasticity of the polydimethylsiloxane matrix and the adhesive polydimethylsiloxane matrix containing 0.4 wt% Triton x-100 was analyzed.

Referring to FIG. 4, it can be seen that the loss tangent decreases as the curing temperatures of PDMS_40, a4-PDMS_40, a4-PDMS_50 and a4-PDMS_70 decrease. In addition, a4-PDMS_40 shows a high loss tangent value of about 0.5 even at a low frequency of 0.1 Hz.

The loss tangent value of the silicone rubber in the prior art was found to be less than 0.4 or less than 0.1, indicating that a4-PDMS_40 exhibits a very high viscoelasticity compared to other silicone-based elastomers.

Based on the above uniaxial tensile test and viscoelastic measurement, the adhesive polydimethylsiloxane matrix having a curing temperature of 40 ° C and containing 0.3 wt% of Triton x-100 or 0.4 wt% of Triton x-100 was mixed with Triton x-100 It is more flexible and has higher viscoelasticity than the polydimethylsiloxane matrix not added.

5A is a graph showing an adhesion force measured by a peel test of a sticky polydimethylsiloxane matrix according to an embodiment of the present invention, and FIGS. 5B to 5H are graphs showing the adhesion force measured by a peel test ≪ / RTI > and Figure 5i shows an image of a tacky polydimethylsiloxane matrix supporting various weights.

The adhesion of the polydimethylsiloxane matrix and the adhesive polydimethylsiloxane matrix was measured by a peel test according to the ASTM D3330 standard at a peel angle of 90 占 and the test apparatus is shown in the inset image of FIG. 5a.

The sample size for the adhesion measurement was 100 mm × 25 mm, the peeling speed was fixed at 300 mm · min ^-1 , and the force of the load cell was 20 N. Also, the test environment was maintained at 25 ± 2 ° C and 45 ± 5% relative humidity.

Referring to FIG. 5A, a3-PDMS_40 and a4-PDMS_40 exhibited the highest adhesion among all the samples. The adhesion of a3-PDMS_40 is 35 Nm ^-1 , which is 7 times higher than the adhesion of the polydimethylsiloxane matrix.

Referring to FIGS. 5B to 5H, the adhesive force-distance of the sample measured by the fill test shows that the adhesive strength of a3-PDMS_40 and a4-PDMS_40 is the highest.

Referring to FIG. 5I, a 7.7g coin, 30g brass block, and 50g brass block were attached to a finger using a4-PDMS_40, respectively. As a result, a4-PDMS_40 showed that a brass block having a weight of 50g State can be maintained.

5A-5I, it can be seen that the thermosetting temperature affects the adhesion of the adhesive polydimethylsiloxane matrix. The very low modulus of elasticity and viscoelasticity of the thermosetting adhesive polydimethylsiloxane matrix at 40 < 0 > C improves the wetting and spreading of the polymer chains in the adhesive polydimethylsiloxane matrix, thereby improving surface contact and the adhesion of the adhesive polydimethylsiloxane matrix Is improved.

FIGS. 6A and 6B are graphs showing swelling ratios of the adhesive polydimethylsiloxane matrix according to an embodiment of the present invention, and FIGS. 6C and 6D are graphs showing gel fractions. FIG.

The optical properties of the adhesive polydimethylsiloxane matrix are strongly influenced by the content of Triton x-100, and mechanical properties such as Young's modulus, breaking strain, viscoelasticity and adhesion force greatly affect the thermosetting temperature of the adhesive polydimethylsiloxane matrix Receive.

The swelling ratio and gel fraction of the adhesive polydimethylsiloxane matrix and the polydimethylsiloxane matrix were measured in order to explain the effect of the content of triton x-100 on the Young's modulus, viscoelasticity and adhesive strength. As the solvent for the measurement, chloroform and Toluene was used.

6A and 6B, it can be seen that the swelling ratio of a4-PDMS_40 is 2.5 times and 2 times higher than that of PDMS_40 in chloroform and toluene, respectively.

6C and 6D, the gel fraction of a4-PDMS_40 is 0.8 and 0.77 in chloroform and toluene, respectively, and PDMS_40 has values of 0.95 and 1.0 in chloroform and toluene, respectively.

Specifically, the expansion ratios in chloroform and toluene solvents are expressed as a function of the curing temperature of a4-PDMS and PDMS_40, respectively, and the expansion ratio and gel fraction are defined by the following equations (2) and (3), respectively.

6A and 6B, the swelling ratios of a4-PDMS_40 are 2.5 times and 2 times higher than those of PDMS_40 when chloroform and toluene are used, respectively. Thus, the swelling ratio of the adhesive polydimethylsiloxane matrix decreases with increasing thermosetting temperature and becomes closer to the swelling ratio of the adhesive polydimethylsiloxane matrix when the thermosetting temperature is above 70 캜.

As shown in FIGS. 6C and 6D, the gel fraction of a4-PDMS_40 was 0.8 and 0.77 in chloroform and toluene, respectively, and values of 0.95 and 1.0 in chloroform and toluene, respectively. Similarly to the swelling ratio, The gel fraction of the polydimethylsiloxane matrix increases with increasing thermosetting temperature and becomes similar to the polydimethylsiloxane matrix when the thermosetting temperature is above 70 캜.

Crosslinking of the polydimethylsiloxane occurs via hydrosilylation using a platinum (Pt) catalyst. The platinum catalyst diffuses through the polydimethylsiloxane matrix to complete the crosslinking reaction. The platinum catalyst forms a complex with other polar functional groups, such as the PEG chain of Triton x-100, because it is coordinately unsaturated.

Triton x-100 also forms a core-shell structure inside the polydimethylsiloxane matrix. Thus, when the non-polar functional group surrounds the platinum-interacting polar group of the Triton x-100 core-shell structure inside the polydimethylsiloxane matrix, the amount of active platinum catalyst present in the polydimethylsiloxane matrix is depleted.

Thus, the crosslinking reaction is inhibited by adding a small amount of Triton x-100 to the polydimethylsiloxane mixture through deactivation of the platinum catalyst, which is the main mechanism for forming a heterogeneously crosslinked network in the polydimethylsiloxane. By a Triton x-100 molecule, a heterogeneously crosslinked network composed of crosslinked and unbridged polydimethylsiloxane is formed in the adhesive polydimethylsiloxane matrix.

Such a composite structure modulates mechanical properties such as Young's modulus, breaking strain, viscoelasticity and adhesion to form a soft and tacky polydimethylsiloxane matrix.

FIGS. 7A and 7B are graphs showing the cell viability and optical microscopic images of fibroblasts for measuring the biocompatibility of the adhesive polydimethylsiloxane matrix according to an embodiment of the present invention, and FIG. 7C is a graph showing the absorbance FIG.

The cell viability and proliferation for measuring the biocompatibility of the adhesive polydimethylsiloxane matrix (the samples used were a4-PDMS_40 and a4-PDMS_70) and the polydimethylsiloxane matrix (the samples used were PDMS_40 and PDMS_70) according to an embodiment of the present invention The velocity was analyzed indirectly. Fibroblast (L929) was grown in a 5% CO ₂ air incubator at 37 ° C. The sample was rinsed with ethanol and UV exposure. The sample was then placed in a 24-well plate and 1 ml of the solution containing fibroblast cells was sprayed onto the sample.

Cell density of the solution is 105 cells · ml ^- was a ^1, the cell viability was analyzed by the CCK-8 kit, the absorbance with a microplate reader (VersaMax, Molecular Devices LLC) was measured at 450 nm.

The cell viability of the sample is defined as the ratio of the number of cells grown on the surface of the sample to the number of cells grown in the control sample (the environment in which the cells grow under the best conditions), and if the cell viability is 80% or more, the sample is considered to be biocompatible.

Referring to FIGS. 7A and 7B, PDMS_40 and a4-PDMS_40 thermally cured at 40 DEG C, PDMS_70 and a4-PDMS_70 thermally cured at 70 DEG C both have cell survival rates of 80% or more, from which triton x- 100 does not affect the biocompatibility of the polydimethylsiloxane matrix.

The cell viability of the sample is defined as the ratio of the number of cells grown on the surface of the sample to the number of cells grown in the control sample (the environment in which the cells grow under the best conditions), and if the cell viability is 80% or more, the sample is considered to be biocompatible.

Referring to FIG. 7C, the addition of Triton x-100 and lowering the thermosetting temperature indicate that the absorbance is lowered. Absorbance is measured using the CCK-8 kit and is proportional to the cell growth rate as the CCK-8 kit detects the signal of living cells.

Therefore, the addition of Triton x-100 and the low thermosetting temperature independently induce a decrease in cell proliferation rate, and a4-PDMS_40 shows a significantly lower cell proliferation rate than the other samples. In order for the cells to proliferate, the surface should be soft enough to allow the cells to grow, and a4-PDMS_40 has a low cell growth rate due to its high surface roughness.

FIG. 8 is a graph showing the light transmittance of a sticky transparent polydimethylsiloxane matrix-based adhesive electrode in which silver nanowires are embedded according to an embodiment of the present invention.

8, may have the nanowires are embedded, viscous transparent electrode that is based on a viscous polydimethylsiloxane matrix containing Triton x-100 0.4% by weight of a heat cured at 40 ℃ has a surface resistance (R _S) Is 35? · Sq ^-1 , and the light transmittance is about 75%.

9A is a graph showing a result of performing a stretch test to evaluate the elasticity of a sticky polydimethylsiloxane matrix-based viscous transparent electrode embedded with silver nanowires according to an embodiment of the present invention, and Figs. 9B to 9E are graphs And a field emission-scanning electron microscopy (FE-SEM) image before and after stretching.

A transparent electrode (PDMS_40NW) based on a polydimethylsiloxane matrix and a transparent electrode (a4-PDMS_40NW) based on a4-PDMS_40 which is a matrix of adhesive polydimethylsiloxane matrix were used to perform the elasticity test and a 500 cycle ).

Only the a4-PDMS_40NW sample was used because the a3-PDMS_40-based transparent electrode (a3-PDMS_40NW) sample was too high for surface resistance to be applied to the transparent electrode.

Referring to FIG. 9A, it can be seen that the ratio (R / R ₀ ) of the surface resistance of a4-PDMS_40NW decreases to 0.8 after 100 cycles and reaches 0.94 after 500 cycles. On the other hand, the ratio of the surface resistance of PDMS_40NW continuously increases and reaches 1.5 after 500 cycles.

Referring to FIG. 9B, it can be seen that the PDMS_40NW can observe severe detachment of silver nanowires even before the periodic elasticity test, and referring to FIG. 9C, it can be seen that the silver nanowires are broken after the periodic elasticity test (FIG. Can be (red dotted line). It can be seen from this that silver nanowires are not well embedded in the polydimethylsiloxane matrix because of the low adhesion between the polydimethylsiloxane matrix and the silver nanowires.

9D, it can be seen that a4-PDMS_40NW does not show detachment of AgNW. Referring to FIG. 9E, after the periodic stretchability test, the a4-PDMS_40NW did not fracture, .

Since the PEG chains of Triton x-100 can participate in electrostatic interactions with silver nanowires, the adhesion between a4-PDMS_40 and silver nanowires is higher than the adhesion between PDMS_40 and silver nanowires.

Since the adhesion between a4-PDMS_40 and silver nanowires is good, the elasticity of a4-PDMS_40NW electrodes is improved. Another reason for the decrease in the surface resistance ratio after 100 stretching is that the alignment of silver nanowires along the stretching direction has changed. According to previous research by other researchers, silver nanowires can be aligned along the stretching direction during mechanical stretching.

Silver nanowires inserted in a4-PDMS_40 can be aligned along the stretching direction during periodic stretching because the adhesion between silver nanowire and a4-PDMS_40 is strong due to Triton x-100.

Hereinafter, characteristics of a viscoelastic polydimethylsiloxane matrix-based viscous transparent electrode having silver nanowires embedded therein according to an embodiment of the present invention applied to a strain sensor and an ECG sensor will be described.

FIG. 10A is a photograph showing a case where a strain sensor using a transparent polydimethylsiloxane matrix-based transparent electrode (a4-PDMS_40NW) embedded with silver nanowires according to an embodiment of the present invention is attached to the wrist, and FIG. (PDMS_40NW) based on polydimethylsiloxane matrix embedded silver nanowires according to an embodiment of the present invention is attached to the wrist.

10A and 10B, the a4-PDMS_40NW showed perfect conformal contact with the skin, and by repeated bending motion of the wrist (the third image in FIG. 10A) It can be seen that it is not peeled off. However, it can be seen that the PDMS_40NW is detached from the skin even in the first bending motion (the second image in Fig. 10B).

FIG. 10C shows a transparent electrode (a4-PDMS_40NW) based on a sticky polydimethylsiloxane matrix embedded with silver nanowires according to an embodiment of the present invention and a polydimethylsiloxane matrix-based sticky transparent electrode (PDMS_40NW) embedded silver nanowires And the relative resistance change of the applied strain sensor.

Referring to FIG. 10C, it can be seen that a4-PDMS_40NW exhibits an electrical resistance change greater than PDMS_40NW for the same applied variation, which indicates that the sensitivity of a4-PDMS_40NW is significantly higher than the sensitivity of PDMS_40NW in a fixed strain . This difference is due to the high conformity and elasticity of a4-PDMS_40NW to skin compared to PDMS_40NW.

In addition, the distortion sensor applying the a4-PDMS_40NW as shown in Figure 10c represents a low hysteresis relative resistance change ^- is maintained at zero during cyclic bending of the (ΔR · R ₀ ¹⁾ s.

However, the strain sensor using PDMS_40NW exhibits a high hysteresis characteristic which greatly degrades the performance of the strain sensor, and the ΔR · R ₀ ^{- 1} ratio of the straight state continuously increases during multiple bending cycles of the wrist.

11A to 11C are cross-sectional views of a transparent electrode (a4-PDMS_40NW) based on a sticky polydimethylsiloxane matrix embedded with silver nanowires according to an embodiment of the present invention and a polydimethylsiloxane matrix-based sticky transparent electrode PDMS_40NW) is attached to the arm, and FIG. 11D is a graph showing the skin impedance measured using the ECG sensor.

Referring to FIG. 11A, in order to measure the skin impedance, an ECG sensor using a4-PDMS_40NW was attached to the arm with an interval of 3 cm and the sensor was well attached to the arm without lifting. Also, if you look at the image below, you can see from the other angles that the sensor is attached to the arm without lifting.

On the other hand, referring to FIG. 11B, it can be seen that when the ECG sensor using PDMS_40NW is attached without the adhesive tape, the adhesion to the skin is not good and it is easily peeled off. Therefore, in order to improve the adhesion to the skin, an ECG sensor using PDMS_40NW was attached using an adhesive tape as shown in FIG. 11C.

Referring to FIG. 11D, in the case of the ECG sensor using the PDMS_40NW, the skin impedance is very high as the adhesion to the skin is poor and the compliance is low.

Therefore, when the ECG sensor using PDMS_40NW, which has poor adhesion to the skin, is adhered using an adhesive tape, the adhesive force to the skin is increased, so that the skin impedance is lower than when the adhesive tape is not used.

In addition, in case of ECG sensor using a4-PDMS_40NW, skin impedance is lower than ECG sensor using PDMS_40NW and ECG sensor using adhesive tape.

From this, it can be seen that when the ECG signal is recorded, the adhesion to the skin is very important.

 FIG. 11E shows a photograph of a transparent electrode (a4-PDMS_40NW) based on a sticky polydimethylsiloxane matrix embedded with silver nanowires separated from the skin according to an embodiment of the present invention.

Referring to FIG. 11E, it can be seen that no residue remains on the skin even after a4-PDMS_40NW is separated from the skin, and skin irritation or allergic reaction due to residues on the skin does not occur, which is advantageous in application of the ECG sensor Able to know.

12A shows electrode positions of an ECG sensor using a transparent polydimethylsiloxane matrix-based transparent electrode (a4-PDMS_40NW) embedded with silver nanowires according to an embodiment of the present invention, and FIGS. 12B to 12E show electrode positions Of the electrocardiogram signal.

Electrocardiogram signals were measured using a commercially available polydimethylsiloxane matrix-based cohesive transparent electrode (PDMS_40NW) embedded with silver nanowires and a transparent polydimethylsiloxane matrix-based transparent electrode (a4- PDMS_40NW) was used as the ECG sensor.

Electrocardiograms were measured by attaching three electrodes on the right side of the chest, on the left side of the chest, and on the lower right side of the chest as shown in FIG. 12A.

12B and 12C, compared to the case of using an ECG sensor using a commercial gel-based transparent electrode as shown in FIG. 12B, as shown in FIG. 12C, in the case of an ECG sensor using a PDMS_40NW, It can be seen that there is a serious noise such that a low signal noise and a distinguishable P wave are not observed.

Referring to FIG. 12D, in the case of the ECG sensor using the adhesive tape to improve the PDMS_40NW and skin contact, the noise of the ECG signal is slightly reduced as compared with the ECG sensor using the PDMS_40NW shown in FIG. 12C, .

Referring to FIG. 12E, it can be seen that the ECG sensor using a4-PDMS_40NW shows much less noise than the ECG sensor using the commercial gel-based transparent electrode shown in FIG. 12B.

FIGS. 13A to 13D show electrode positions of an ECG sensor to which a transparent polydimethylsiloxane matrix-based transparent electrode (a4-PDMS_40NW) embedded with silver nanowires according to an embodiment of the present invention is applied, and FIGS. 13B to 13D Is a graph showing an electrocardiogram signal measured by an ECG sensor.

Electrocardiogram signals were measured using a commercially available polydimethylsiloxane matrix-based cohesive transparent electrode (PDMS_40NW) embedded with silver nanowires and a transparent polydimethylsiloxane matrix-based transparent electrode (a4- PDMS_40NW) was used as the ECG sensor.

In the case of the ECG sensor using PDMS_40NW, an adhesive tape was used to improve contact with the skin.

13A, electrocardiograms were measured by attaching three electrodes to both arms and the left ankle.

Referring to FIGS. 13B to 13D, it can be seen that the noise of the ECG signal is larger than that in the case where the ECG sensor is attached to the chest (see FIGS. 12B to 12E) due to the distance between the electrode and the heart.

Referring to FIG. 13C, the ECG sensor using PDMS_40NW showed very severe noise of the ECG signal even though the contact tape was used to improve the contact force with the skin, and it was found that the contact with the arm skin was very weak .

Referring to FIG. 13D, an ECG sensor using a4-PDMS_40NW shows a clear and stable ECG signal similar to an ECG sensor using a commercial gel-based transparent electrode.

In the case of ECG sensor using a4-PDMS_40NW, the signal has low noise due to high compliance with skin and high electrical conductivity of embedded silver nanowire.

The ECG sensor using a4-PDMS_40NW has higher adhesion to the skin than the ECG sensor using PDMS_40NW, and the biocompatibility is significantly improved compared to ECG sensors using commercial gel-based transparent electrodes.

As described above, the transparent electrode having the silver nanowire network embedded in the adhesive polydimethylsiloxane matrix containing the nonionic surfactant has a high degree of adaptability for application as a skin biosensor.

It can be seen that the conformability of the electrode is improved by improving the mechanical properties such as adhesion, compliance and viscoelasticity of the adhesive polydimethylsiloxane matrix.

Such mechanical properties are due to the interaction of the polar functional groups present in the platinum (Pt) catalyst and the Triton x-100 present in the polydimethylsiloxane curing agent by the addition of Triton x-100, a non-ionic surfactant, Can be improved as the crosslinking reaction of the polydimethylsiloxane is hindered.

Further, in the case of the sensor using the transparent electrode according to the present invention, the detection sensitivity of various bio-signals such as EMG, EEG and glucose can be greatly improved. In addition to the biosensor, a triboelectric nano generator, an optoelectronic device, a transparent thin film heater, And can be used as an electrode material for various wearable electronic devices such as a battery.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but, on the contrary, Modification is possible. Therefore, the scope of the present invention should not be limited to the described embodiments, but should be determined by the equivalents of the claims, as well as the claims.

Claims (10)

Board; And
(PDMS) matrix embedded with a silver (Ag) nanowire network deposited on the substrate,
Wherein the viscous polydimethylsiloxane matrix comprises polydimethylsiloxane comprising a polydimethylsiloxane base and a polydimethylsiloxane curing agent and a nonionic surfactant.
The method according to claim 1,
The crosslinking reaction of the polydimethylsiloxane is hindered by the interaction of the platinum (Pt) catalyst present in the polydimethylsiloxane curing agent and the polar functional groups present in the nonionic surfactant, Wherein the mechanical properties of the dimethylsiloxane matrix are improved.
The method according to claim 1,
Wherein the silver nanowire network is embedded in the adhesive polydimethylsiloxane matrix due to interactions between the polar functional groups present in the nonionic surfactant and the polar functional groups present in the silver nanowire network.
The method according to claim 1,
Wherein the nonionic surfactant is 4- (1,1,3,3-tetramethylbutyl) phenyl-polyethylene glycol.
The method according to claim 1,
Wherein the polydimethylsiloxane subject, the polydimethylsiloxane curing agent and the nonionic surfactant have a weight ratio of 10: 1: 0.01 to 10: 1: 0.08.
Forming a silver nanowire network on the substrate;
Coating a dispersion comprising a polydimethylsiloxane subject, a polydimethylsiloxane curing agent and a nonionic surfactant on the substrate on which the silver nanowire network is formed; And
Thermally curing the dispersion coated on the substrate on which the silver nanowire network is formed to form an adhesive polydimethylsiloxane matrix having the silver nanowire network embedded therein
The method of manufacturing a transparent conductive adhesive electrode according to claim 1,
The method according to claim 6,
Further comprising the step of separating the adhesive polydimethylsiloxane matrix from which the silver nanowire network is embedded. ≪ RTI ID = 0.0 > 18. < / RTI >
The method according to claim 6,
The step of forming a nanowire network on the substrate
Coating a silver nanowire solution on the substrate; And
And annealing the substrate coated with the silver nanowire solution. ≪ RTI ID = 0.0 > 11. < / RTI >
9. The method of claim 8,
Wherein the substrate coated with the silver nanowire solution is annealed at 100 ° C to 180 ° C for 5 minutes to 20 minutes.
The method according to claim 6,
Wherein the dispersion coated on the substrate on which the silver nanowire network is formed is thermally cured at 40 < 0 > C to 80 < 0 > C.

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