KR101510597B1 - Flexible micro gas sensor using nanostructure array and manufacturing method for the same - Google Patents

Abstract

The flexible micro gas sensor using the carbon nanotube array structure according to the present invention comprises a flexible substrate; An electrode layer formed on the flexible substrate; A carbon film layer laminated in such a manner that the flexible substrate and the electrode layer are entirely or partially covered; And a carbon nanotube layer formed on the carbon film layer, wherein the carbon nanotube layer is grown from a metal catalyst deposited on the carbon film layer.
The flexible gas sensor according to the present invention utilizes the reactivity of the carbon nanotubes with the reducing gas and the flexible characteristics of the carbon nanotubes. As a result, various applications are possible without restriction to various electronic products. Further, since it can be used at room temperature without using a separate heater, miniaturization, high performance, and portability of the apparatus can be maximized.

Description

Technical Field [0001] The present invention relates to a flexible micro gas sensor using a carbon nanotube array structure,

The present invention relates to a flexible micro carbon gas sensor using a carbon nanotube array structure and a manufacturing method thereof, and more particularly, to a micro carbon nanotube sensor capable of detecting gas even at room temperature by using high density carbon nanotubes for various gas detection, The present invention also relates to a flexible micro gas sensor using a carbon nanotube array structure capable of precisely measuring a carbon nanotube by widening a reaction area with a gas and a method of manufacturing the same.

Generally, an oxide semiconductor gas sensor is a sensor that senses a gas to be detected in such a manner as to measure a change in electrical conductivity that occurs when an oxide semiconductor reacts with a gas. Such an oxide semiconductor gas sensor can be manufactured inexpensively in a small size, has many advantages such as high sensitivity and high response speed as well as high stability at high temperature and is widely used.

However, it is difficult to detect low concentration nitrogen dioxide or ethanol at room temperature in the conventional oxide semiconductor sensor, and the sensor for detecting the sensor is operated in a high temperature environment by a heater, so that various applications are limited.

In addition, although various gas sensors utilizing nanostructures that maximize the surface area and reactivity with gas have been developed (see Korean Patent Publication No. 10-2012-0121511), the manufacturing process that can be applied to a flexible substrate having flexibility is limited There is a problem.

Therefore, a problem to be solved by the present invention is to provide a flexible gas sensor which is applied to a flexible substrate and maximizes reactivity with a gas to be detected, and a manufacturing method thereof.

According to an aspect of the present invention, there is provided a flexible micro gas sensor using a carbon nanotube array structure, comprising: a flexible substrate; An electrode layer formed on the flexible substrate; A carbon film layer laminated in such a manner that the flexible substrate and the electrode layer are entirely or partially covered; And a carbon nanotube layer formed on the carbon film layer, wherein the carbon nanotube layer is grown from a metal catalyst deposited on the carbon film layer.

The carbon film layer may be one of a group including graphene, graphite, carbon black, carbon nanotube (CNT), and carbon nanofiber (CNF) .

The metal catalyst may be one selected from the group consisting of iron, nickel, aluminum, molybdenum, magnesium, cobalt and palladium.

A method of fabricating a flexible micro gas sensor using a carbon nanotube array structure according to another aspect of the present invention includes the steps of: preparing a flexible substrate; Forming an electrode layer on the flexible substrate; Laminating the carbon film layer in a state of wholly or partially covering the flexible substrate and the electrode layer; Laminating a metal layer on the carbon film layer to form a metal catalyst layer; And growing a carbon nanotube on the metal catalyst by injecting a carbon source onto the carbon film layer and the metal catalyst layer.

The step of forming the metal catalyst layer includes a step of patterning the metal catalyst layer.

The step of growing the carbon nanotubes includes disposing a flexible substrate on which the carbon film layer and the metal catalyst layer are laminated, in a chamber in which the temperature sequentially rises from a room temperature to a preset reference temperature.

The step of growing the carbon nanotubes includes disposing a flexible substrate on which the carbon film layer and the metal catalyst layer are laminated in a chamber different from a predetermined reference temperature.

The metal catalyst may be one selected from the group consisting of iron, nickel, aluminum, molybdenum, magnesium, cobalt and palladium.

The flexible gas sensor according to the present invention utilizes the reactivity of carbon nanotubes with oxidizing and reducing gases and the flexible characteristics of carbon nanotubes. As a result, various applications are possible without restriction to various electronic products. Further, since it can be used at room temperature without using a separate heater, miniaturization, high performance, and portability of the apparatus can be maximized.

1 to 3 are views illustrating a method of manufacturing a flexible micro gas sensor using a carbon nanotube array structure according to an embodiment of the present invention.
4 to 9 are views illustrating a method of manufacturing a flexible micro gas sensor using a carbon nanotube array structure according to another embodiment of the present invention.
10 is a graph of experimental data obtained after carbon nanotubes are grown regardless of orientation after coating a metal catalyst layer on a carbon film layer without patterning.

The present invention grows carbon nanotubes on a flexible substrate and utilizes them to detect various gases. Therefore, since a wide reaction area of the carbon nanotube and the carbon film layer can be utilized in the reaction with the gas, more precise gas measurement is possible.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. It should be understood, however, that the invention is not limited to the disclosed embodiments, but is capable of other various forms of implementation, and that these embodiments are provided so that this disclosure will be thorough and complete, It is provided to let you know completely.

It should be noted that, in adding reference numerals to the constituent elements of the drawings, the same constituent elements are denoted by the same reference numerals even though they are shown in different drawings. In the following description of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear.

In describing the components of the present invention, terms such as first, second, A, B, (a), and (b) may be used. These terms are intended to distinguish the constituent elements from other constituent elements, and the terms do not limit the nature, order or order of the constituent elements. When a component is described as being "connected", "coupled", or "connected" to another component, the component may be directly connected or connected to the other component, Quot; may be "connected,""coupled," or "connected. &Quot;

1 and 2 are views illustrating a method of manufacturing a flexible micro gas sensor using a carbon nanotube array structure according to a first embodiment of the present invention.

Referring to FIG. 1, a plurality of metal catalysts 110 are stacked on a flexible substrate 100 such as a thin metal layer having a polymer, a glass, or an insulating layer. The metal catalyst 110 may be fabricated in a patterned manner after the metal layers are stacked to form a plurality of independent lines or points. The metal catalyst may be selected from the group consisting of iron, nickel, aluminum, molybdenum, magnesium, cobalt and palladium, and combinations thereof may be used. However, the scope of the present invention is limited to the above- It does not.

Referring to FIG. 2, a carbon source such as hydrocarbon is injected into the metal catalyst 110 to vertically grow the carbon nanotubes 120 from the metal catalyst 110. In particular, the present invention utilizes the reactivity between the reducing gas and the vertically grown carbon nanotubes, the flexible mechanical properties of the carbon nanotubes, and the large surface area of the carbon nanotubes for gas detection.

As a result, various applications are possible without restriction to various electronic products. Further, since it can be used at room temperature without using a separate heater, miniaturization, high performance, and portability of the apparatus can be maximized.

Meanwhile, as shown in FIG. 3, after the carbon nanotubes 120 have grown sufficiently, the metal catalyst 110 may not be completely consumed.

Next, a flexible micro gas sensor using a carbon nanotube array structure according to a second embodiment of the present invention will be described with reference to FIGS. 4 to 5. FIG.

The flexible micro gas sensor shown in Fig. 4 includes a flexible substrate 200 such as a thin metal layer having plastic or insulating layers, an electrode layer 202 formed on the flexible substrate 200 through etching or the like, a flexible substrate 200, And a carbon nanotube layer 220 formed in a direction perpendicular to the carbon film layer 205. The carbon nanofiber layer 220 is formed on the carbon film layer 205, Here, for example, the carbon film layer 205 is coated over a plurality of electrodes spaced a predetermined distance in an opposite polarity state.

5 includes a flexible substrate 200, an electrode layer 202, a carbon film layer 205, and a carbon nanotube layer 220 'sequentially. However, the flexible micro gas sensor shown in FIG. 5 includes a carbon nanotube layer 220 'are formed freely in a random direction without any set direction.

The carbon film layer 205 improves adhesiveness in the process of growing carbon nanotubes on the metal catalyst by injecting a carbon source. Specifically, the adhesion between the carbon film layer 205 and the carbon source injected during the formation of the carbon nanotubes facilitates the growth of the carbon nanotube layer 220 '.

The carbon film layer 205 is a carbon material capable of preventing breakage or cracking by applying an elastic force to the flexible substrate 200. The carbon film layer 205 is preferably made of graphene, graphite, carbon black, It is preferable to include at least one carbon material selected from the group consisting of carbon nanotubes (CNTs) and carbon nanofibers (CNFs).

The carbon film layer 205 may be formed by coating the above carbon material on the flexible substrate 200 by vapor deposition or by coating by a coating method.

At this time, the coating method may be performed by a method such as spray coating, gravure coating, micro gravure coating, Kiss Gravure coating, Comma Knife coating, roll coating, A Meyer Bar coating, a Slot Die coating, and a Reverser coating method may be used, but the present invention is not limited thereto.

Next, the formation structure of the catalyst required for manufacturing the flexible micro gas sensor according to the present invention will be described with reference to FIGS. 6 to 7. FIG.

The catalyst forming structure in FIG. 6 is a structure in which metal layers are laminated in a state where the flexible substrate 200, the electrode layer 202, and the carbon film layer 205 are sequentially laminated, and then the metal catalyst 210 is manufactured in a patterned manner A plurality of independent lines or points can be formed. The metal catalyst 210 may be iron, nickel, or the like, but the scope of the present invention is not limited to the specific kind of metal as described above.

7, the metal catalyst 210 is stacked without additional patterning in a state where the flexible substrate 200, the electrode layer 202, and the carbon film layer 205 are sequentially stacked.

Next, a manufacturing method of a flexible micro gas sensor using the metal catalyst 210 processed in a patterned manner will be described with reference to FIG.

First, a flexible substrate 200 such as a thin metal layer having a plastic or insulating layer is prepared (Fig. 8A).

An electrode layer 202 is formed on the flexible substrate 200 through an optical angle or the like (Fig. 8B). As a specific example, the electrode layer 202 may be molybdenum (Mo), gold (Au), silver (Ag), or platinum (Pt) electrodes formed on the substrate 200 using the photolithography method, The platinum electrode, silver, may be advantageous as a metal that can withstand temperatures of about 500 ° C or higher during growth of single-walled carbon nanotubes by the thermochemical method.

The carbon film layer 205 is laminated so as to cover the flexible substrate 200 and the electrode layer 202 in whole or in part (Fig. 8C).

After the metal film is laminated on the carbon film layer 205, the metal catalyst layer 210 is patterned to produce a plurality of independent lines or dot shapes (FIG. 8D).

Next, the carbon nanotubes 120 are grown vertically on the metal catalyst 110 by injecting a carbon source such as a hydrocarbon onto the carbon film layer 205 and the patterned metal catalyst layer 210, (Figs. 8E and 8F).

Specifically, the step of vertically growing the carbon nanotubes 120 is possible by exposing the flexible micro gas sensor on the chamber gradually from a room temperature to a high temperature (for example, 600 DEG C) (FIG. 8E) .

On the other hand, the process of growing the carbon nanotubes 120 without direction is possible by a method of exposing the flexible micro gas sensor in comparison with a chamber having an internal temperature of a high temperature (for example, 600 DEG C) (FIG. 8F) .

As shown in FIGS. 8E and 8F, the metal catalyst 110 may be completely removed after performing the catalytic function in the process of growing the carbon nanotubes 120.

Referring to FIG. 9, a method of manufacturing a flexible micro gas sensor using a metal catalyst 210 that is kept in a laminated state without additional patterning will be described.

The manufacturing method is substantially the same as the manufacturing method using the patterned metal catalyst in FIG. 8, except for the patterning process in FIG. 8D.

As shown in FIGS. 9E and 9F in this method, carbon nanotubes 220 and 220 'are formed by injecting a carbon source such as a hydrocarbon onto the carbon film layer 205 and the un-patterned metal catalyst layer 210 Allowing them to grow vertically or grow without directionality.

10 is a graph showing test results using a sensor fabricated by applying the present invention. FIG. 10 is a graph showing experimental data after carbon nanotubes are grown regardless of orientation after coating a metal catalyst layer on the carbon film layer without patterning to be.

In this experiment, ethanol is used as the gas to be detected, and the test is conducted under the conditions of a pressure of 2.5 Torr, an applied voltage of 5 V, and a temperature of 25 캜. The horizontal axis represents the sensing time and the vertical axis represents the resistance value for determining the degree of detection.

In the experimental method, a sensor is attached in a chamber, and a vacuum atmosphere is created in the chamber. Then, a change in resistance according to concentration is measured while gas in and out (gas out) . In this case, the sensitivity of the sensor can be calculated by the following equation.

S (Sensitivity) = {(R _gas - R _o ) / R _o } × 100

Where R _o is the initial resistance value of the sensor and R _gas is defined as the resistance value of the sensor measured when the specific gas is introduced at a specific concentration. As a result, the resistance value changed relative to the initial resistance value of the sensor Value - initial resistance value).

Therefore, the larger the value of sensitivity, the better the performance of the sensor. Here, the sign of sensitivity does not matter.

For the reference, the carbon film type sensor developed in the present invention showed a sensitivity of about 3.53, and when compared with the conventional CNT / iso-butyl methyl ketone composite thick film type sensor, Respectively.

It is to be understood that the terms "comprises", "comprising", or "having" as used in the foregoing description mean that the constituent element can be implanted unless specifically stated to the contrary, But should be construed as further including other elements. All terms, including technical and scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs, unless otherwise defined. Commonly used terms, such as predefined terms, should be interpreted to be consistent with the contextual meanings of the related art, and are not to be construed as ideal or overly formal, unless expressly defined to the contrary.

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. It is clear that the present invention can be suitably modified and applied in the same manner. Therefore, the above description does not limit the scope of the present invention, which is determined by the limitations of the utility model registration claims.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the scope of the present invention.

Claims (8)

As a flexible micro gas sensor using a carbon nanotube array structure,
A flexible substrate;
An electrode layer formed on the flexible substrate;
A carbon film layer laminated in such a manner that the flexible substrate and the electrode layer are entirely or partially covered; And
And a carbon nanotube layer formed on the carbon film layer,
Wherein the carbon nanotube layer is grown from a metal catalyst deposited on the carbon film layer.
Flexible micro gas sensor using carbon nanotube array structure.
The method according to claim 1,
The carbon film layer may be formed of any one of a group including graphene, graphite, carbon black, carbon nanotubes (CNT), and carbon nanofibers (CNF) sign,
Flexible micro gas sensor using carbon nanotube array structure.
The method according to claim 1,
Wherein the metal catalyst is any one selected from the group consisting of iron, nickel, aluminum, molybdenum, magnesium, cobalt,
Flexible micro gas sensor using carbon nanotube array structure.
A manufacturing method of a flexible micro gas sensor using a carbon nanotube array structure according to any one of claims 1 to 3,
Preparing a flexible substrate;
Forming an electrode layer on the flexible substrate;
Laminating the carbon film layer in a state of wholly or partially covering the flexible substrate and the electrode layer;
Laminating a metal layer on the carbon film layer to form a metal catalyst layer; And
And injecting a carbon source onto the carbon film layer and the metal catalyst layer to grow carbon nanotubes on the metal catalyst.
A method of manufacturing a flexible micro gas sensor.
5. The method of claim 4,
Wherein the forming of the metal catalyst layer comprises:
And patterning the metal catalyst layer.
A method of manufacturing a flexible micro gas sensor.
5. The method of claim 4,
The step of growing the carbon nanotubes comprises:
Disposing a flexible substrate in which the carbon film layer and the metal catalyst layer are laminated in a chamber in which the temperature rises sequentially from a room temperature to a preset reference temperature,
A method of manufacturing a flexible micro gas sensor.
5. The method of claim 4,
The step of growing the carbon nanotubes comprises:
And disposing a flexible substrate in which the carbon film layer and the metal catalyst layer are laminated in a chamber different from a predetermined reference temperature.
A method of manufacturing a flexible micro gas sensor.
5. The method of claim 4,
Wherein the metal catalyst is any one selected from the group consisting of iron, nickel, aluminum, molybdenum, magnesium, cobalt,
A method of manufacturing a flexible micro gas sensor.

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