CN108489375A - Dimension sensor production method based on carbon nanotube - Google Patents

Abstract

The present invention provides a kind of dimension sensor production method based on carbon nanotube and prepares carbon nanotube by chemical vapour deposition technique first；Carbon nanotube is prepared into uniaxial sample and twin shaft sample again, to which uniaxial dimension sensor and twin shaft dimension sensor be made.Using dimension sensor made from this method it is orthogonal horizontally and vertically on all have good resistance change rate, sensor sensitivity is good.

Description

Fabrication method of two-dimensional sensor based on carbon nanotubes

technical field

The invention relates to the technical field of sensors, in particular to a method for manufacturing a two-dimensional sensor based on carbon nanotubes.

Background technique

Sensor, as the name suggests, is an instrument that transmits "feeling"; the so-called "feeling" is reflected in various physical and chemical signals in the field of natural science. A sensor can convert a certain physical signal into another observable or measurable (electrical, optical) signal. Commonly used sensors include temperature sensors (thermistors, thermocouples), pressure sensors, displacement sensors, displacement sensors, strain sensors (strain gauges), light sensors (photodiodes), chemical sensors, biological sensors, etc.

A strain sensor, also known as a strain gauge, can convert the strain amount into an electrical signal output, and is a sensor based on measuring the strain generated by the force deformation of an object. It has a wide range of applications in the fields of mechanics, medicine, material science and construction.

Electronic devices that stretch, fold, or deform into complex curvilinear shapes can add many new functions that previous rigid electronic components could not. These electronics work well for displays, cameras for electronic eyes, and skin sensors. For the development of flexible conductors, a method developed in recent years is to fabricate a wave-like or mesh-like conductive structure layer, and then place it on a pre-stretched elastomeric substrate. For different elastic conductors, such as metal-coated mesh corrugated plates, corrugated metal wires or two-dimensional metal films have been disclosed in the existing literature.

Carbon nanotubes have a large aspect ratio, good electrical conductivity, high thermal and mechanical strength. Theoretical calculations show that the tensile strength and elastic modulus of carbon nanotubes are very high, in the order of Tpa, and it has also been confirmed experimentally. Carbon nanotubes also have a very significant elastic response to deformation, and theoretical calculation methods show that the fracture strain of carbon nanotubes is between 15% and 18%. This makes them promising as stretchable conductors. Although carbon nanotubes have been deeply studied in flexible transparent electrodes, there is still a lot of room for research in stretchability. Recently, a composite sheet composed of carbon nanotubes, ionic liquids, and fluorinated copolymers, which acts as an elastic conductor, exhibits excellent electrical conductivity when stretched. This elastic conductor can still maintain good conductivity when stretched by 700%. However, their conductivity still decreases linearly with strain.

Contents of the invention

The technical problem to be solved by the present invention is: in order to overcome the deficiencies in the prior art, the present invention provides a method for manufacturing a two-dimensional sensor based on carbon nanotubes, using a flexible conductor through its different stretching in the horizontal and vertical directions A two-dimensional strain sensor is produced by changing the resistance generated by the situation.

The technical scheme adopted by the present invention to solve its technical problems is: a method for manufacturing a two-dimensional sensor based on carbon nanotubes, comprising the following steps:

Step 1: preparing carbon nanotubes by chemical vapor deposition;

Step 1.1: Use iron (1nm)/aluminum oxide (10nm) placed on a silicon wafer as a catalyst, ethylene as a carbon source, use argon and hydrogen mixed gas as a carrier gas, and maintain an environment of 750 degrees Celsius, on the surface of the catalyst Form multi-walled carbon nanotubes CNTs, and synthesize CNT arrays on a quartz tube furnace by chemical vapor deposition;

Step 1.2: Use a blade to scrape the CNT sheet off the CNT array; on the edge of the CNT array, stick the stretched CNT with the blade, and then pull it out continuously to form a CNT sheet;

Step 2: sample preparation, the sample preparation includes uniaxial sample preparation or biaxial sample preparation;

During sample preparation, SEBS rubber was used as the flexible substrate of CNT. Preferably, SEBS rubber was G-1651H from American Kraton Company. The shape of SEBS rubber can be any shape and size, select according to user needs, in order to facilitate the comparison of transverse and longitudinal characteristics, the present invention selects square SEBS rubber, and the stretch ratio depends on the tensile properties of SEBS, and the present invention draws The elongation ratio is preferably 4 times, and the size requirements of the CNT flakes are as long as the SEBS used as the flexible substrate is larger than the carbon nanotube size.

Uniaxial sample preparation,

Take a square piece of SEBS rubber (50mm×50mm), and stretch it 4 times horizontally and vertically; take two sections of CNT sheets (50mm×40mm) and place them horizontally on the SEBS rubber to obtain a single-axis two-dimensional sensor, and complete the single-axis Production of samples; when removing CNT from the silicon wafer, generally drop alcohol on SEBS, CNT will be fully connected with SEBS, and the alcohol will also volatilize, which will not affect the test.

Biaxial sample preparation,

Take a square piece of SEBS rubber (50mm×50mm), and stretch it 4 times horizontally and vertically. Take a piece of CNT sheet (50mm×40mm) and place it horizontally on SEBS rubber, and then take a section of CNT sheet (50mm×40mm) and place it vertically on SEBS rubber to obtain a biaxial two-dimensional sensor and complete the production of biaxial samples. Two segments of CNT flakes are stacked perpendicular to each other.

The beneficial effects of the present invention are: the present invention provides a method for manufacturing a two-dimensional sensor based on carbon nanotubes, and the two-dimensional sensor prepared by this method has good resistance changes in the horizontal and vertical directions perpendicular to each other The greater the rate of change, the more sensitive the sensor.

Description of drawings

The present invention will be further described below in conjunction with drawings and embodiments.

Fig. 1 is the fabrication flowchart of the two-dimensional sensor based on carbon nanotubes of the present invention;

Figure 2(a) is the SEM image of the CNT flakes on the surface of the uniaxial sample at low magnification;

Figure 2(b) is the SEM image of the CNT flakes on the surface of the uniaxial sample at high magnification;

Figure 2(c) is the SEM image of the CNT flakes on the surface of the biaxial sample at low magnification;

Figure 2(d) is the SEM image of the CNT flakes on the surface of the biaxial sample at high magnification;

Figure 3(a) is a schematic diagram of the horizontal stretching of the uniaxial sample;

Figure 3(b) is a graph of the relationship between the horizontal stretch and the resistance change rate of the uniaxial sample;

Figure 3(c) is a schematic diagram of the vertical stretching of the uniaxial sample;

Figure 3(d) is a graph of the relationship between the tensile and the resistance change rate of the uniaxial sample in the vertical direction;

Figure 4(a) is a schematic diagram of biaxial sample stretching in the vertical direction;

Figure 4(b) is a graph of the relationship between the vertical stretch and the resistance change rate of the biaxial sample;

Detailed ways

The present invention will be described in detail in conjunction with accompanying drawing now. This figure is a simplified schematic diagram only illustrating the basic structure of the present invention in a schematic manner, so it only shows the components relevant to the present invention.

As shown in Figure 1, a kind of carbon nanotube-based two-dimensional sensor fabrication method of the present invention comprises the following steps: comprising the following steps:

Step 1: preparing carbon nanotubes by chemical vapor deposition;

Step 1.1: Use iron (1nm)/aluminum oxide (10nm) placed on a silicon wafer as a catalyst, ethylene as a carbon source, use argon and hydrogen mixed gas as a carrier gas, and maintain an environment of 750 degrees Celsius, on the surface of the catalyst Form multi-walled carbon nanotubes CNTs, and synthesize CNT arrays on a quartz tube furnace by chemical vapor deposition;

Step 1.2: Use a blade to scrape the CNT sheet off the CNT array; on the edge of the CNT array, stick the stretched CNT with the blade, and then pull it out continuously to form a CNT sheet;

Step 2: sample preparation, the sample preparation includes uniaxial sample preparation or biaxial sample preparation;

During sample preparation, SEBS rubber was used as the flexible substrate of CNT. Preferably, SEBS rubber was G-1651H from American Kraton Company. The shape of SEBS rubber can be any shape and size, select according to user needs, in order to facilitate the comparison of transverse and longitudinal characteristics, the present invention selects square SEBS rubber, and the stretch ratio depends on the tensile properties of SEBS, and the present invention draws The elongation ratio is preferably 4 times, and the size requirements of the CNT flakes are as long as the SEBS used as the flexible substrate is larger than the carbon nanotube size.

Uniaxial sample preparation,

Take a square piece of SEBS rubber (50mm×50mm), and stretch it 4 times horizontally and vertically; take two sections of CNT sheets (50mm×40mm) and place them horizontally on the SEBS rubber. In the same direction, a single-axis two-dimensional sensor is obtained, and the production of a single-axis sample is completed;

Biaxial sample preparation,

Take a square piece of SEBS rubber (50mm×50mm), and stretch it 4 times horizontally and vertically. Take a piece of CNT sheet (50mm×40mm) and place it horizontally on SEBS rubber, and then take a section of CNT sheet (50mm×40mm) and place it vertically on SEBS rubber to obtain a biaxial two-dimensional sensor and complete the production of biaxial samples. Two segments of CNT flakes are stacked perpendicular to each other.

The performance evaluation and test of the prepared two-dimensional sensor were carried out, and the test supplies included silver glue and Keithley2400 multimeter.

(1) Characterization of carbon nanotubes

Carbon nanotubes were prepared by chemical vapor deposition, and they were fabricated into uniaxial and biaxial samples, respectively. SEM images of scanning electron microscope images taken at different magnifications. Figure 2(a) and Figure 2(b) are the SEM images of the uniaxial sample at low and high magnifications, respectively. It can be seen from the figure that the surface of the uniaxial sample has a regular wrinkled structure. Figure 2(c) and Figure 2(d) are the SEM images of the biaxial sample at low and high magnifications, respectively. It can be seen that the surface of the biaxial sample is different from the wrinkled structure of the uniaxial sample, and is a new wrinkled structure formed by the combination of longitudinal and transverse wrinkles. The width of the CNT flakes can be controlled in the range of millimeters to centimeters by changing the width of the contact between the blade and the CNT array, and the thickness of the CNTs is usually tens of nanometers. The present invention mainly studies the average diameter of CNT flakes is 7nm, and the column thickness is about 300μm.

(2) Tensile property test of uniaxial sample

As shown in Figure 3(a), select three non-overlapping positions on the uniaxial sample, and number them as 1, 2, and 3, and apply conductive silver glue to the three positions. The selection of the three positions can be arbitrary. , but cannot overlap each other. Slowly stretch 50%, 100%, 150%, 200%, 250% along the direction of 1 to 2 (that is, the horizontal direction). Measure the resistances R ₁₂ , R ₁₃ , and R ₂₃ between any two points 1, 2, and 3 with a Keithley 2004 multimeter every stretch. Then slowly retract 50%, 100%, 150%, 200%, 250% along the 21 direction. At the same time, measure the resistance R ₁ ' ₂ , R ₁ ' ₃ , and R' ₂₃ between any two points 1, 2, and 3 with a Keithley2004 multimeter each time it is retracted. According to the formula ΔR=R-R0, the resistance change rate can be calculated, wherein, R is the resistance value measured by Keithley2004, and R0 is the resistance value before stretching.

Fig. 3(b) is a graph showing the relationship between stretching in the horizontal direction and the rate of change in resistance. In the 12-direction, 23-direction and 31-direction, the resistance change rate increases with the increase of the stretch, and decreases with the decrease of the stretch. However, in the 12-direction, the change rate of resistance under the same stretching condition is relatively smaller than that of the 23-direction and 13-direction. This is because in the 12 direction, the resistance is stretched and shortened along the wrinkle direction, and the resistance change is relatively small.

As shown in Fig. 3(c), slowly stretch 50%, 100%, 150%, 200%, 250% along the direction perpendicular to 12. Use Keithley2004 to measure the resistances R ₁₂ , R ₁₃ , and R ₂₃ between any two points 1, 2, and 3 every stretch. Then slowly retract 50%, 100%, 150%, 200%, 250% along the direction perpendicular to 21. At the same time, use Keithley2004 to measure the resistance R ₁ ' ₂ , R ₁ ' ₃ , R' ₂₃ between any two points 1, 2, and 3 each time you retract, and the resistance change can be calculated according to the formula ΔR=R-R0 Rate.

Fig. 3(d) is a graph showing the relationship between vertical stretch and resistance change rate. In the 23 direction and 31 direction, the resistance change rate increases with the increase of the stretch, and decreases with the decrease of the stretch, and the resistance change rate shows a change that approaches a straight line. But in the 12 direction, the resistance change rate hardly changes linearly with the stretching or shortening of the sample. This is due to the fact that when the sample is stretched and shortened perpendicular to the wrinkle direction, the wrinkles of the carbon nanotubes are hardly pulled apart, and therefore, the electrical resistance hardly changes significantly.

(3) Tensile property test of biaxial sample

The change of the uniaxial sample in the direction perpendicular to the wrinkle is not obvious, which has obvious disadvantages as a two-dimensional sensor. In order to solve the problem that the change of the sensor is not obvious in the direction perpendicular to the wrinkle, biaxial samples were fabricated. As shown in Figure 4(a), select three positions on the biaxial sample and number them 1, 2, and 3, and apply conductive silver glue to the three positions. The three positions can be arbitrary, but they cannot overlap each other. Slowly stretch 50%, 100%, 150%, 200%, 250% along the direction perpendicular to 12. Use Keithley2004 to measure the resistances R ₁₂ , R ₁₃ , and R ₂₃ between any two points 1, 2, and 3 every stretch. Then slowly retract 50%, 100%, 150%, 200%, 250% along the direction perpendicular to 21. At the same time, use Keithley2004 to measure the resistance R ₁ ' ₂ , R ₁ ' ₃ , R' ₂₃ between any two points 1, 2, and 3 each time it is retracted. According to the formula ΔR=R-R0, the resistance change rate can be calculated .

Fig. 4(b) is a graph showing the relationship between stretching in the horizontal direction and the rate of change in resistance. In the 12-direction, 23-direction and 31-direction, the resistance change rate increases with the increase of the stretch, and decreases with the decrease of the stretch. It can be seen from the figure that the biaxial sample successfully solves the problem that the resistance change rate does not change significantly when the uniaxial sample is stretched and shortened perpendicular to the wrinkle direction.

The arrows in the figure indicate the stretching direction.

Inspired by the ideal embodiment according to the present invention, through the above description, relevant workers can make various changes and modifications without departing from the scope of the present invention. The technical scope of the present invention is not limited to the content in the specification, and its technical scope must be determined according to the scope of the claims.

Claims (1)

1. a kind of dimension sensor production method based on carbon nanotube, it is characterised in that：Include the following steps：

Step 1：Carbon nanotube is prepared by chemical vapour deposition technique；

Step 1.1：Using iron (the 1nm)/alundum (Al2O3) (10nm) placed on silicon as catalyst, ethylene is as carbon Source maintains 750 DEG C of environment temperature using argon and hydrogen gas mixture as current-carrying gas, and multi wall is formed in catalyst surface Carbon nanotube CNT synthesizes CNT array on quartz tube furnace by chemical vapor deposition；

Step 1.2：CNT thin slices are scraped off from CNT array with blade again；In the marginal portion of CNT array, adhered to blade The CNT stretched, is then constantly released, a CNT thin slice is formed；

Step 2：Sample preparation, the sample preparation include uniaxial sample preparation or twin shaft sample preparation；

The single shaft sample preparation includes the following steps：

One block of SEBS rubber is taken, it horizontal and vertical is stretched respectively；Two sections of CNT thin slices are taken to be placed across SEBS rubber On, uniaxial dimension sensor is obtained, the making of uniaxial sample is completed；

The twin shaft sample preparation includes the following steps：

One block of SEBS rubber is taken, it horizontal and vertical is stretched respectively；One section of CNT thin slice is taken to be placed across SEBS rubber On, then take one section of CNT thin slice placed longitudinally on SEBS rubber, twin shaft dimension sensor is obtained, the making of twin shaft sample is completed.