KR102234735B1 - High sensitive microporous pressure sensor with low hysteresis fabricated by microfluidic systems - Google Patents

Abstract

The present invention is to control the size of the micelle structure by using a microfluidic system, the pore size of the porous pressure sensor can be adjusted, as well as the manufacture of a pressure sensor that can have high durability and high sensitivity by synthesizing a conductive polymer on the surface It's about the method. The present invention comprises the steps of (a) mixing a non-polar solvent and a linear polymer; (b) forming a micelle structure by supplying the mixed solution of step (a) and a polar solvent to one channel; (c) heating the micelle structure flowing out of the channel to polymerize the linear polymer, and evaporating the solvent to obtain a porous structure; And (d) depositing a conductive polymer on the surface of the porous structure prepared in step (c).

Description

High sensitive microporous pressure sensor with low hysteresis fabricated by microfluidic systems}

The present invention relates to a method for manufacturing a highly sensitive pressure sensor having a low hysteresis phenomenon using a microfluidic system, and more particularly, by controlling the size of a micelle structure using a microfluidic system, and controlling the pore size of the porous pressure sensor The present invention relates to a method of manufacturing a pressure sensor capable of having high durability and high sensitivity by synthesizing a conductive polymer on the surface as well as possible.

Along with the 4th industrial revolution, interest in robots is increasing, and tactile sensor research is being actively conducted to give robots the same sense as humans. Since the core of human tactile sense is pressure, research on pressure sensors is being focused among tactile sensors. Until now, many pressure sensors have been developed and researched, but there are many problems to be solved for commercialization.

One of the problems is uniformity. Uniformity means that when a number of sensors are manufactured, all of them exhibit the same performance. Although one of the sensors reported through the existing literature is outstanding, reproducibility and uniformity are inferior due to structural constraints.

Another problem with pressure sensors that are currently being reported is hysteresis. The hysteresis phenomenon means that the sensor does not return to the same signal point before and after the structure changes due to stimulation. When such a phenomenon occurs, the initial resistance value of the sensor continuously fluctuates, making it impossible to accurately measure a signal, and the reliability of the sensor data decreases.

Therefore, when solving the problems of sensor uniformity, hysteresis, and sensitivity, which are preventing the commercialization of pressure sensors, it will be possible to manufacture pressure sensors that can be used in various ways in artificial skin, touch screens, and wearable materials.

(0001) Korean Patent Application Publication No. 10-2018-0072521 (0002) Korean Patent Publication No. 10-0605028

The present invention is to control the size of the micelle structure by using a microfluidic system, the pore size of the porous pressure sensor can be adjusted, as well as the manufacture of a pressure sensor that can have high durability and high sensitivity by synthesizing a conductive polymer on the surface I want to provide a way.

In order to solve the above problem, the present invention comprises the steps of: (a) mixing a non-polar solvent and a linear polymer; (b) forming a micelle structure by supplying the mixed solution of step (a) and a polar solvent to one channel; (c) heating the micelle structure flowing out of the channel to polymerize the linear polymer, and evaporating the solvent to obtain a porous structure; And (d) depositing a conductive polymer on the surface of the porous structure prepared in step (c).

The non-polar solvent may be benzene, hexane, toluene, xylene, hexadecane, octadecane, or nonadecane.

The linear polymer may be polydimethylsiloxane (PDMS) or allyhydrocarboxsliane.

The polar solvent may be water or chloroform.

The step (b) may be a step performed using a microfluidic system.

The step (c) is performed at 50 to 100° C., and may be a step in which polymerization of the linear polymer is first performed, and then evaporation of the solvent is performed.

Before depositing the conductive polymer in step (d), a step of attaching a functional group through plasma treatment and then attaching a polymer polymerization aid may be further included.

The plasma treatment may be performed using O2 plasma.

The polymer composite preparation may be pyrrolesilane.

The conductive polymer in step (d) may be pyrrole or poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT; PSS).

The step (d) may be performed in the presence of an Fe3+ catalyst.

The present invention also provides a pressure sensor manufactured by the above manufacturing method.

The method for manufacturing a highly sensitive pressure sensor with a low hysteresis using a microfluidic system according to the present invention overcomes the low sensitivity of the pressure sensor and non-uniformity of the sensor characteristics by manufacturing a porous structure through a micelle structure using a microfluidic system. In addition to being able to, by having a strong chemical bond with the conductive polymer synthesized on the surface through surface activation, the occurrence of hysteresis can be minimized, and thus a pressure sensor with high sensitivity and accuracy can be provided. , Medical surgical tools, flexible touch screens, wearable electronic materials, etc. can be usefully used.

1 is an optical micrograph after polymerization of a micelle structure, a porous structure, and a conductive polymer according to an embodiment of the present invention.
2 is a graph showing the results of FT-IR analysis after depositing a conductive polymer (pyrrole) according to an embodiment of the present invention.
3 is a graph showing the sensitivity according to the size of the micelle structure of the pressure sensor according to an embodiment of the present invention.
Figure 4 is a graph measuring the reaction rate of the pressure sensor according to an embodiment of the present invention.
Figure 5 is a graph measuring the hysteresis phenomenon of the pressure sensor according to an embodiment of the present invention.
6 is a graph showing the results of a durability test of a pressure sensor according to an embodiment of the present invention.
7 is a graph showing the results of a durability test of a conventional CNT-based sensor.

Hereinafter, a preferred embodiment of the present invention will be described in detail. In describing the present invention, when it is determined that a detailed description of a related known technology may obscure the subject matter of the present invention, a detailed description thereof will be omitted. Throughout the specification, when a part "includes" a certain component, it means that other components may be further included rather than excluding other components unless otherwise stated.

The present invention is intended to illustrate specific embodiments and to be described in detail in the detailed description, since various transformations may be applied and various embodiments may be provided. However, this is not intended to limit the present invention to a specific embodiment, it should be understood to include all conversions, equivalents, or substitutes included in the spirit and scope of the present invention.

The terms used in the present invention are used only 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 invention, terms such as include or have are intended to designate the presence of features, numbers, steps, actions, components, parts, or a combination of them described in the specification, and one or more other features, numbers, and steps. It is to be understood that it does not preclude the possibility of the presence or addition of, operations, components, parts, or combinations thereof.

The present invention comprises the steps of (a) mixing a non-polar solvent and a linear polymer; (b) forming a micelle structure by supplying the mixed solution of step (a) and a polar solvent to one channel; (c) heating the micelle structure flowing out of the channel to polymerize the linear polymer, and evaporating the solvent to obtain a porous structure; And (d) depositing a conductive polymer on the surface of the porous structure prepared in step (c).

The step (a) is a step of mixing a linear polymer in a non-polar solvent to form a micelle structure, and when the linear polymer mixed in the non-polar solvent is mixed with a polar solvent, the micelles are arranged in a spherical shape while containing a non-polar solvent therein. To form a structure. The non-polar solvent used at this time may be benzene, hexane, toluene, xylene, hexadecane, octadecane, or nonadecane, and preferably hexadecane may be used. In addition, it is preferable to use polydimethylsiloxane (PDMS) or allyhydrocarboxsliane as the linear polymer. In addition, it is preferable to mix the linear polymer and the non-polar solvent so as to have a ratio of 1:10 to 3:1 based on weight. When mixed to have a ratio of less than 1:10, the ratio of linear polymers may be lowered and micelle structure may not be formed, and when mixed to have a ratio of less than 1:3, the ratio of linear polymers may increase, resulting in agglomeration. And, accordingly, it may bring about nonuniformity of the porous diatom and reduction of voids.

The step (b) is a step of forming a micelle structure by supplying the mixed solution of step (a) and a polar solvent to one channel, and is preferably performed using a microfluidic system. At this time, the solution and the polar solution in step (a) are supplied through different supply paths, and are mixed in channels in the microfluidic system to form micelles. In addition, when the microfluidic system is used, since micelles having the same diameter as the diameter of the channel are formed, the pore size in the porous structure can be adjusted by adjusting the diameter of the channel. In this case, it is preferable to use water or chloroform as the polar solvent used, and the amount of the micelle structure outflow can be controlled by adjusting the amount of water supplied.

The step (c) is a step of heating the micelle structure flowing out of the channel to polymerize the linear polymer, and evaporating the solvent to obtain a porous structure. It is performed at 50 to 100°C, and the polymerization of the linear polymer is first performed, and then , It may be a step in which evaporation of the solvent is performed. As shown in the first figure of FIG. 1, when the micelle structures are regularly arranged and the polymers constituting the micelle structure are polymerized, a porous structure having the same structure as the arrangement of the micelle structures can be prepared. However, if the non-polar solvent constituting the core of the micelle structure or the external polar solvent evaporates before polymerization of the polymer, such a porous structure may not be produced. Therefore, in the case of the linear polymer, it is preferable to polymerize at a temperature lower than the evaporation of the solvent, and it is preferable that the polymerization of the linear polymer is carried out first and then the solvent is evaporated to remove as the temperature increases. Therefore, if the step (c) is performed at less than 50°C, the solvent may be evaporated without polymerization of the polymer. If it is performed at a temperature exceeding 100°C, the solvent may be removed before polymerization of the polymer is completed. It is difficult to obtain a homogeneous porous structure because the evaporation is performed. It is more preferable that the step (c) is performed at 80°C.

The step (d) is a step of polymerizing a conductive polymer on the surface of the porous structure prepared in step (c). Before polymerizing the conductive polymer to increase the bonding strength between the porous structure and the conductive polymer, plasma treatment is performed. After attaching the functional group, it is preferable to attach the polymer synthesis aid. At this time, the plasma treatment is performed using O2 plasma, and it is more preferable to use pyrrolesilane as a polymer synthesis aid. In addition, in the case of the conductive polymer, it is preferable to use pyrrole or poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT; PSS), and it is more preferable to perform this polymerization in the presence of a Fe3+ catalyst in order to smoothly perform the polymerization.

The present invention also provides a pressure sensor manufactured by the above method.

Hereinafter, embodiments of the present application will be described in detail with reference to the accompanying drawings so that those of ordinary skill in the art can easily implement the present invention. However, the present application may be implemented in various different forms and is not limited to the embodiments described herein. In the drawings, parts not related to the description are omitted in order to clearly describe the present invention.

Example

A solution obtained by mixing polydimethylsiloxane and hexadecane at a weight ratio of 1:1 was supplied to the microfluidic system, while water was injected into the other inlet of the channel to form a micelle structure. At this time, the inner diameter of the channel and the transfer pipe was set to 300 μm, and accordingly, a micelle structure having a size of about 300 μm could be formed (the first picture of FIG. 1).

After the micelle structure was arranged in a certain shape, it was heated at 80° C. for 1 hour. At this time, it was confirmed that the polydimethylsilonic acid was polymerized, and then the hexadecane and water evaporated to form a porous structure (Fig. 1). Second picture).

The prepared porous structure was subjected to O2 plasma treatment to attach a functional group, and then pyrrolesilane was bonded to the functional group through chemical vapor deposition. Finally, polymerization was performed on the surface of the structure using a mixture of pyrrole and Fe + catalyst (third figure in FIG. 1).

Experimental example

FIG. 1 shows a photograph of a micelle structure formed by a microfluidic system arranged in a certain shape, a photograph of a porous structure after curing, and a photograph after polymerization of pyrrole, a conductive polymer, respectively. As shown in the first figure of FIG. 1, as the micelle structure was uniformly repeated, a porous structure in which a uniform shape was repeated could be obtained, and accordingly, it was confirmed that the uniform shape was maintained even after the conductive polymer was polymerized. .

2 is a graph showing FT-IR analysis after depositing a conductive polymer (pyrrole). As shown in Figure 2, it was confirmed that the pyrrole was normally deposited.

3 is a graph measuring the sensitivity of the sensor according to the size of pores, that is, the size of the micelle structure. As shown in FIG. 3, it was confirmed that the sensitivity of the sensor can be changed by adjusting the size of the micelle, which can be controlled by adjusting the size of the transfer tube of the microfluidic system.

4 is a result of measuring the reaction rate of the pressure sensor manufactured according to the present invention, it was confirmed that the change in resistance was performed immediately according to the change in pressure.

5 is a graph measuring the hysteresis phenomenon of the pressure sensor according to the present invention, and it can be seen that when three different pressures are applied, the hysteresis limit appears to be negligibly small.

6 is a graph of the results of the durability test, it was confirmed that the size of the signal did not change even after 1000 repeated pressure tests. In contrast to this, in the case of the existing CNT-based pressure sensor, it was confirmed that the size of the signal changes (Fig. 7).

As described above, specific parts of the present invention have been described in detail, and it will be apparent to those of ordinary skill in the art that these specific techniques are only preferred embodiments, and the scope of the present invention is not limited thereby. will be. Accordingly, it will be said that the substantial scope of the present invention is defined by the appended claims and their equivalents.

Claims (12)

(a) mixing a non-polar solvent and a linear polymer;
(b) forming a micelle structure by supplying the mixed solution of step (a) and a polar solvent to one channel;
(c) heating the micelle structure flowing out of the channel to polymerize the linear polymer, and evaporating the solvent to obtain a porous structure; And
(d) polymerizing a conductive polymer on the surface of the porous structure prepared in step (c);
Including,
The linear polymer is polydimethylsiloxane (PDMS) or allylhydrocarboxysilane,
The step (c) is carried out at 50 ~ 100 ℃, polymerization of the linear polymer is first performed, and then evaporation of the solvent is performed.
The method of claim 1,
The method of manufacturing a pressure sensor, wherein the non-polar solvent is benzene, hexane, toluene, xylene, hexadecane, octadecane or nonadecane.
delete The method of claim 1,
The polar solvent is a method of manufacturing a pressure sensor, characterized in that water and chloroform.
The method of claim 4,
The (b) step is a method of manufacturing a pressure sensor, characterized in that the step is performed using a microfluidic system.
delete The method of claim 1,
Before depositing the conductive polymer of step (d), attaching a functional group through plasma treatment, and then attaching a polymer polymerization aid.
The method of claim 7,
The method of manufacturing a pressure sensor, characterized in that the plasma treatment is performed using O2 plasma.
The method of claim 7,
The method of manufacturing a pressure sensor, wherein the polymer polymerization aid is pyrrolesilane.
The method of claim 1,
The conductive polymer in step (d) is pyrrole or poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT; PSS).
The method of claim 1,
The step (d) is a method of manufacturing a pressure sensor, characterized in that it is carried out in the presence of Fe 3 + catalyst.
A pressure sensor manufactured by the method of any one of claims 1, 2, 4, 5, and 7 to 11.

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