KR102239323B1 - Pressure sensor including arranged carbon nanotube sheet and method of manufacturing the same - Google Patents

Abstract

A pressure sensor including a carbon nanotube sheet includes a first substrate, a first electrode, a second electrode, a carbon nanotube sheet, and a second substrate. The first electrode is disposed on the first substrate. The second electrode is disposed on the first substrate and is spaced apart from the first electrode in a first direction. The carbon nanotube sheet is disposed on the first substrate and disposed between the first electrode and the second electrode. The second substrate is disposed on the first electrode, the second electrode, and the carbon nanotube sheet. The carbon nanotube sheet includes a plurality of carbon nanotube strings extending in a second direction different from the first direction.

Description

A pressure sensor including an aligned carbon nanotube sheet and a method of manufacturing the same {PRESSURE SENSOR INCLUDING ARRANGED CARBON NANOTUBE SHEET AND METHOD OF MANUFACTURING THE SAME}

The present invention relates to a pressure sensor and a method of manufacturing the same, and more particularly, to a pressure sensor using the impedance characteristic of a carbon nanotube sheet and a method of manufacturing the same.

The recent rapid development of mobile devices and the Internet of Things requires the implementation of high-performance sensors that can be applied to wearable electronic devices, electronic skin, soft robotics, and health care.Therefore, researches to create various sensors using transparent and flexible materials are underway. have.

Republic of Korea Patent Publication No. 10-2014-0125903 Republic of Korea Patent Publication No. 10-2014-0114918

An object of the present invention is to provide a pressure sensor using the impedance characteristic of a carbon nanotube sheet.

Another object of the present invention is to provide a method of manufacturing the pressure sensor.

A pressure sensor including a carbon nanotube sheet according to an embodiment for realizing the object of the present invention includes a first substrate, a first electrode, a second electrode, a carbon nanotube sheet, and a second substrate. The first electrode is disposed on the first substrate. The second electrode is disposed on the first substrate and is spaced apart from the first electrode in a first direction. The carbon nanotube sheet is disposed on the first substrate and disposed between the first electrode and the second electrode. The second substrate is disposed on the first electrode, the second electrode, and the carbon nanotube sheet. The carbon nanotube sheet includes a plurality of carbon nanotube strings extending in a second direction different from the first direction.

In an embodiment of the present invention, when pressure is applied to the second substrate, the pressure may be sensed by measuring signals from the first electrode and the second electrode.

In one embodiment of the present invention, the first substrate may be a transparent and flexible material.

In an embodiment of the present invention, the first substrate may include polydimethylsiloxane (PDMS).

In one embodiment of the present invention, the second substrate may be a transparent and flexible material.

In an embodiment of the present invention, the second substrate may include polydimethylsiloxane (PDMS).

In an embodiment of the present invention, the carbon nanotube sheet may further include carbon nanotube strings that are connected to each other or cross each other.

In an embodiment of the present invention, the pressure sensor may sense resistance and capacitance using the first electrode and the second electrode.

In one embodiment of the present invention, the equivalent circuit of the pressure sensor may include one resistor and one capacitor connected in parallel with each other.

일 수 있다.In one embodiment of the present invention, when the resistance is R, the capacitance is C, and the impedance of the pressure sensor is Z,

Can be

In one embodiment of the present invention, when the pressure applied to the pressure sensor increases, the resistance may increase.

일 수 있다. 상기 압력 센서에 가해지는 상기 압력이 증가하면 상기 제1 전극 및 상기 제2 전극 사이의 경로의 길이(l)가 증가하여 상기 레지스턴스가 증가할 수 있다.In an embodiment of the present invention, a specific resistance of a path between the first electrode and the second electrode is ρ, a length of a path between the first electrode and the second electrode is l, and the first electrode and the second electrode are 2 When the area of the path between the electrodes is s,

Can be When the pressure applied to the pressure sensor increases, the length l of the path between the first electrode and the second electrode increases, and the resistance may increase.

In one embodiment of the present invention, when the pressure applied to the pressure sensor increases, the capacitance may decrease.

일 수 있다. 상기 압력 센서에 가해지는 상기 압력이 증가하면 상기 카본 나노튜브 스트링들 사이의 평균 거리(d)가 증가하여 상기 캐패시턴스가 감소할 수 있다.In an embodiment of the present invention, the dielectric constant defined by the carbon nanotube sheet disposed between the first electrode and the second electrode is ε, the area of the dielectric is A, and between the carbon nanotube strings. When the average distance of is d,

Can be When the pressure applied to the pressure sensor increases, the average distance d between the carbon nanotube strings increases, so that the capacitance may decrease.

In an embodiment of the present invention, the second direction may be perpendicular to the first direction.

A method of manufacturing a pressure sensor according to an embodiment for realizing another object of the present invention includes forming a plurality of carbon nanotube strings extending in one direction from a carbon nanotube forest on a first substrate, the first Forming a first electrode on a substrate and a second electrode spaced apart from the first electrode in a first direction, and forming a second substrate on the first electrode, the second electrode, and the carbon nanotube sheet Includes. The carbon nanotube strings extend in a second direction different from the first direction.

The pressure sensor according to the present invention comprises a carbon nanotube sheet having carbon nanotube strings arranged in a parallel direction. The pressure sensor is light transmissive and flexible, and has an equivalent circuit electrically connected in parallel with a resistor and a capacitor. Therefore, it is possible to manufacture a transparent flexible sensor having both resistance characteristics and capacitance characteristics.

The transparent and flexible pressure sensor can be used in various types of high-performance sensor devices that can be applied to mobile devices and IoT devices including wearable characteristics.

1 is a perspective view showing a pressure sensor according to an embodiment of the present invention.
2 is a cross-sectional view showing the pressure sensor of FIG. 1.
3 is a view showing the carbon nanotube sheet of FIG. 1.
4 is an enlarged view of part A of the carbon nanotube of FIG. 3.
5 is an equivalent circuit diagram of the pressure sensor of FIG. 1.
6 is a graph showing the impedance of the pressure sensor of FIG. 1.
7 is a graph showing the magnitude and phase of the impedance of the pressure sensor of FIG. 1 according to the frequency of the input voltage.
8 is a graph showing changes in resistance and capacitance when pressure is applied to the pressure sensor of FIG. 1.
9A is a view showing a state of the carbon nanotube sheet when no pressure is applied to the pressure sensor of FIG. 1.
9B is a view showing a state of the carbon nanotube sheet when pressure is applied to the pressure sensor of FIG. 1.
10A to 10E are diagrams illustrating a method of manufacturing the pressure sensor of FIG. 1.

With respect to the embodiments of the present invention disclosed in the text, specific structural or functional descriptions have been exemplified for the purpose of describing the embodiments of the present invention only, and the embodiments of the present invention may be implemented in various forms. It should not be construed as being limited to the embodiments described in.

Since the present invention can be modified in various ways and has various forms, specific embodiments will be illustrated in the drawings and described in detail in the text. However, this is not intended to limit the present invention to a specific form disclosed, it should be understood to include all changes, equivalents, or substitutes included in the spirit and scope of the present invention.

Terms such as first and second may be used to describe various elements, but the elements should not be limited by the terms. The terms may be used for the purpose of distinguishing one component from another component. For example, without departing from the scope of the present invention, a first element may be referred to as a second element, and similarly, a second element may be referred to as a first element.

When a component is referred to as being "connected" or "connected" to another component, it is understood that it may be directly connected or connected to the other component, but other components may exist in the middle. It should be. On the other hand, when a component is referred to as being "directly connected" or "directly connected" to another component, it should be understood that there is no other component in the middle. Other expressions describing the relationship between components, such as "between" and "directly between" or "adjacent to" and "directly adjacent to" should be interpreted as well.

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

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

Meanwhile, when a certain embodiment can be implemented differently, a function or operation specified in a specific block may occur differently from the order specified in the flowchart. For example, two consecutive blocks may actually be executed at the same time, or the blocks may be executed in reverse, depending on a related function or operation.

Hereinafter, preferred embodiments of the present invention will be described in more detail with reference to the accompanying drawings. The same reference numerals are used for the same elements in the drawings, and duplicate descriptions for the same elements are omitted.

1 is a perspective view showing a pressure sensor according to an embodiment of the present invention. 2 is a cross-sectional view showing the pressure sensor of FIG. 1. 3 is a view showing the carbon nanotube sheet of FIG. 1. 4 is an enlarged view of part A of the carbon nanotube of FIG. 3.

1 to 4, the pressure sensor includes a first substrate 100, a first electrode 210, a second electrode 220, a carbon nanotube sheet, and a second substrate 300.

The first substrate 100 may include a transparent material. In addition, the first substrate 100 may include a flexible material. For example, the first substrate 100 may include polydimethylsiloxane (PDMS).

The first electrode 210 may be disposed on the first substrate 100. The first electrode 210 may include a material having conductivity. For example, the first electrode 210 may include a metal. For example, the first electrode 210 may contain silver.

The second electrode 220 may be disposed on the first substrate 100. The second electrode 220 may include a material having conductivity. For example, the second electrode 220 may include a metal. For example, the second electrode 220 may contain silver.

The second electrode 220 may be disposed to be spaced apart from the first electrode 210. The second electrode 220 may be spaced apart from the first electrode 210 in a first direction D1.

The carbon nanotube sheet may be disposed on the first substrate 100. The carbon nanotube sheet may be disposed between the first electrode 210 and the second electrode 220. The carbon nanotube sheet may include a plurality of carbon nanotube strings CNTS extending in a second direction D2 different from the first direction D1.

For example, the second direction D2 in which the carbon nanotube strings CNTS extend may be perpendicular to the first direction D1.

The carbon nanotube strings CNTS of the carbon nanotube sheet generally extend toward the second direction D2, but may have a partially bent portion or a bent portion. Some of the carbon nanotube strings CNTS of the carbon nanotube sheet may be connected to each other or cross each other.

Referring to FIG. 3, a portion of the carbon nanotube sheet is shown, and most of the carbon nanotube strings CNTS extend along the second direction D2. The carbon nanotube strings CNTS may have different thicknesses. FIG. 4 is an enlarged view of a part of FIG. 3 and shows the accumulation.

The second substrate 300 may be disposed on the first electrode 210, the second electrode 220, and the carbon nanotube sheet.

The second substrate 300 may include a transparent material. In addition, the second substrate 300 may include a flexible material. For example, the second substrate 300 may include polydimethylsiloxane (PDMS). The second substrate 300 may include the same material as the first substrate 100.

When pressure is applied on the second substrate 300, the pressure may be sensed by measuring signals from the first electrode 210 and the second electrode 220.

5 is an equivalent circuit diagram of the pressure sensor of FIG. 1. 6 is a graph showing the impedance of the pressure sensor of FIG. 1. 7 is a graph showing the magnitude and phase of the impedance of the pressure sensor of FIG. 1 according to the frequency of the input voltage.

1 to 7, the pressure sensor may sense both the resistance R and the capacitance C using the first electrode 210 and the second electrode 220.

The equivalent circuit of the pressure sensor may include one resistor R and one capacitor C connected in parallel with each other.

6 shows the impedance of the pressure sensor. When the resistance is R and the capacitance is C, the impedance Z of the pressure sensor is expressed by Equation 1 below.

[Equation 1]

The real component (Z _Re) and imaginary components (Z _Im) when divided represented by the real component (Z _Re) of the impedance of the same as the equation (2), 6 is a pressure sensor the impedance (Z) of the pressure sensor to the horizontal axis _{And the imaginary component (Z Im} ) of the impedance of the pressure sensor is plotted on the vertical axis.

[Equation 2]

Z=Z _Re +jZ _Im

The rightmost lower part of the graph of FIG. 6 is a part in which only _{the real component (Z Re) of the impedance (Z) of the pressure sensor exists, and is} This indicates a case where the frequency is 0. The lower leftmost part of the graph of FIG. 6 shows a case where the frequency of the input voltage applied to the first electrode 210 and the second electrode 220 is 10 ^{7 Hz.}

In the graph of FIG. 6, MEASURED means an impedance actually measured from the pressure sensor, and FITTED means a curve connecting the measured impedance. As shown in FIG. 6, since the pressure sensor exhibits an ideal impedance curve of one resistor and one capacitor, the pressure sensor can be modeled to have an equivalent circuit of one resistor and one capacitor.

In the graph of FIG. 7, the horizontal axis represents the frequency of the input voltage, and the vertical axis represents the magnitude of the impedance (|Z|) and the phase of the impedance (PHASE). The magnitude of the impedance can be expressed by Equation 3, and the phase of the impedance PHASE can be expressed by Equation 4.

[Equation 3]

[Equation 4]

8 is a graph showing changes in resistance and capacitance when pressure is applied to the pressure sensor of FIG. 1. 9A is a view showing a state of the carbon nanotube sheet when no pressure is applied to the pressure sensor of FIG. 1. 9B is a view showing a state of the carbon nanotube sheet when pressure is applied to the pressure sensor of FIG. 1.

In FIG. 8, the frequency of the input voltage is set to 100 KHz, the magnitude of the input voltage is set to 50 mV, pressure is applied to the pressure sensor, and the resistance (R) and capacitance (C) of the pressure sensor are measured. . A case in which the first pressure (PRESSURE1) is applied between about 33 sec and about 63 sec to the pressure sensor, and the second pressure is applied between about 93 sec and about 120 sec is illustrated.

1 to 9B, when the pressure applied to the pressure sensor increases, the resistance R may increase.

The specific resistance of the path between the first electrode 210 and the second electrode 220 is ρ, the length of the path between the first electrode 210 and the second electrode 220 is l, and the first electrode When the area of the path between 210 and the second electrode 220 is s, the resistance R of the pressure sensor may be expressed by Equation 5.

[Equation 5]

When the pressure applied to the pressure sensor increases, the length (l) of the path between the first electrode 210 and the second electrode 220 increases as shown in FIG. 9B, and accordingly, the pressure The resistance R of the sensor is increased.

When the pressure applied to the pressure sensor increases, the capacitance C may decrease.

The dielectric constant defined by the carbon nanotube sheet disposed between the first electrode 210 and the second electrode 220 is ε, the area of the dielectric is A, and between the carbon nanotube strings CNTS When the average distance of is d, the capacitance C of the pressure sensor may be expressed by Equation 6.

[Equation 6]

When the pressure applied to the pressure sensor increases, the average distance (d) between the carbon nanotube strings CNTS increases as shown in FIG. 9B, and thus the capacitance (C) of the pressure sensor by Equation 6 Decreases.

10A to 10E are diagrams illustrating a method of manufacturing the pressure sensor of FIG. 1.

1 to 10A, the first substrate 100 may be disposed.

1 to 10B, a plurality of carbon nanotube strings CNTS extending in one direction from the carbon nanotube forest may be formed on the first substrate 100. A metal material M may be used to form the plurality of carbon nanotube strings CNTS.

1 to 10C, the carbon nanotube strings CNTS are formed on the first substrate 100. Since the first substrate 100 includes a transparent and flexible material, the first substrate 100 on which the carbon nanotube strings CNTS are formed may be bent as shown in FIG. 10C.

1 to 10D, the first electrode 210 on the first substrate 100 and the second electrode 220 spaced apart from the first electrode 210 in a first direction D1 Can form more. The carbon nanotube strings CNTS may be disposed between the first electrode 210 and the second electrode 220. Here, the carbon nanotube strings CNTS may extend in a second direction D2 different from the first direction D1.

1 to 10E, a second substrate 300 may be formed on the first electrode 210, the second electrode 220, and the carbon nanotube strings CNTS.

According to this embodiment, the pressure sensor includes a carbon nanotube sheet having carbon nanotube strings CNTS arranged in a parallel direction. The pressure sensor is light-transmitting, flexible, and has an equivalent circuit electrically connected to a resistor (R) and a capacitor (C) in parallel. Therefore, it is possible to manufacture a transparent flexible sensor having both resistance characteristics and capacitance characteristics.

The present invention relates to a transparent and flexible pressure sensor, and the transparent and flexible pressure sensor can be widely used in various types of high-performance sensor elements applicable to a mobile device including wearable characteristics and the Internet of Things.

Although described above with reference to preferred embodiments of the present invention, those skilled in the art will be able to variously modify and change the present invention within the scope not departing from the spirit and scope of the present invention described in the following claims. You will understand that you can.

100: first substrate 210: first electrode
220: second electrode 300: second substrate
CNTS: carbon nanotube string

Claims (16)

A first substrate;
A first electrode disposed on the first substrate;
A second electrode disposed on the first substrate and spaced apart from the first electrode in a first direction;
A carbon nanotube sheet disposed on the first substrate and disposed between the first electrode and the second electrode; And
And a second substrate disposed on the first electrode, the second electrode, and the carbon nanotube sheet,
The carbon nanotube sheet includes a plurality of carbon nanotube strings extending in a second direction different from the first direction,
The pressure sensor senses resistance and capacitance using the first electrode and the second electrode,
The equivalent circuit of the pressure sensor includes one resistor and one capacitor connected in parallel with each other,
When the resistance is R, the capacitance is C, and the impedance of the pressure sensor is Z,

Pressure sensor comprising a carbon nanotube sheet, characterized in that. The pressure sensor of claim 1, wherein when a pressure is applied on the second substrate, the pressure is sensed by measuring signals from the first electrode and the second electrode. The pressure sensor of claim 1, wherein the first substrate is made of a transparent and flexible material. The pressure sensor of claim 3, wherein the first substrate comprises polydimethylsiloxane (PDMS). The pressure sensor of claim 3, wherein the second substrate is made of a transparent and flexible material. The pressure sensor of claim 5, wherein the second substrate comprises polydimethylsiloxane (PDMS). The pressure sensor according to claim 1, wherein the carbon nanotube sheet further comprises carbon nanotube strings connected to each other or crossing each other. delete delete delete The pressure sensor according to claim 1, wherein the resistance increases as the pressure applied to the pressure sensor increases. The method of claim 11, wherein a specific resistance of a path between the first electrode and the second electrode is ρ, a length of a path between the first electrode and the second electrode is l, and between the first electrode and the second electrode When the area of the path of is s,

Is,
When the pressure applied to the pressure sensor increases, a length (l) of a path between the first electrode and the second electrode increases, thereby increasing the resistance. The pressure sensor according to claim 11, wherein the capacitance decreases when the pressure applied to the pressure sensor increases. The method of claim 13, wherein the dielectric constant defined by the carbon nanotube sheet disposed between the first electrode and the second electrode is ε, the area of the dielectric is A, and an average distance between the carbon nanotube strings Is d,

Is,
When the pressure applied to the pressure sensor increases, the average distance (d) between the carbon nanotube strings increases and the capacitance decreases. The pressure sensor of claim 1, wherein the second direction is perpendicular to the first direction. Forming a plurality of carbon nanotube strings extending in one direction from the carbon nanotube forest on the first substrate;
Forming a first electrode on the first substrate and a second electrode spaced apart from the first electrode in a first direction; And
Forming a second substrate on the first electrode, the second electrode, and the carbon nanotube strings,
The carbon nanotube strings extend in a second direction different from the first direction,
The pressure sensor senses resistance and capacitance using the first electrode and the second electrode,
The equivalent circuit of the pressure sensor includes one resistor and one capacitor connected in parallel with each other,
When the resistance is R, the capacitance is C, and the impedance of the pressure sensor is Z,

Method of manufacturing a pressure sensor comprising a carbon nanotube sheet, characterized in that.

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