CN113998666B - A highly sensitive all-graphene artificial electronic skin resistant to ultra-large strains - Google Patents

Abstract

The invention discloses a high-sensitivity full-graphene artificial electronic skin capable of resisting super-large strain, which comprises a flexible substrate, an electrode pattern array prepared from low-density nucleation graphene and a channel prepared from high-density nucleation graphene and having sensitive mechanical response, wherein the electrode pattern array is formed by the low-density nucleation graphene; the electrode pattern array and the channel are arranged on the surface of the flexible substrate, and the two corresponding electrodes are communicated through the channel; the beneficial effects of the invention are as follows: the artificial electronic skin can be prepared in a large area, so that the artificial electronic skin can be processed, a device array with stable mechanical properties can be produced in batches, the artificial electronic skin of all grapheme can bear ultra-large strain and is not broken, and the sensitivity factor of the artificial electronic skin based on grapheme to external strain response is greatly improved; the preparation process is compatible with the existing semiconductor processing technology, namely the artificial electronic skin has good application potential and wide application value.

Description

A highly sensitive all-graphene artificial electronic skin resistant to ultra-large strains

technical field

The invention belongs to the technical field of nanotechnology, and in particular relates to a high-sensitivity all-graphene artificial electronic skin which can resist super large strain and can be used in the fields of artificial electronic skin, flexible touch screen, wearable health monitoring equipment and the like.

Background technique

Artificial electronic skin, also known as skin-like electronics, is an electronic system composed of a series of highly sensitive electronic components that can simulate the function of human skin. In addition to having good flexibility and elasticity like skin, it should also have the ability to sense changes in the external environment (temperature, humidity, stress, etc.), and can be widely used in robotics, monitoring technology and other fields. For artificial electronic skin, the core is the sensor part. Different types of sensors can sense changes in the external environment such as stress, temperature, humidity and other conditions in real time, and then convert them into corresponding electrical signals. In recent years, considering the new requirements for device miniaturization and structural flexibility, two-dimensional materials have achieved rapid development in the research of artificial electronic skin due to their excellent electrical and mechanical properties. Among them, the single atomic layer structure of graphene It better meets the needs of thin and light artificial electronic skin.

Graphene is the lightest material so far and has excellent mechanical strength, which is 100 times that of steel materials. Its tensile strength and elastic modulus are 125GPa and 1.1TPa respectively, which is the highest mechanical strength among known materials. This stretchability also shows great potential in flexible electronics applications. In addition, graphene's good transparent conductivity (mobility exceeds 20,000 cm2/Vs), and its ability to bend arbitrarily with the substrate makes it possible for it to be widely used in artificial point skin.

Although the various excellent properties of graphene bring the possibility of its application in artificial electronic skin, its zero-gap energy band structure determines that it is more similar to a semi-metallic material, and its resistivity changes when stress is applied. Satisfy, where the Poisson's ratio represents the rate at which the cross-sectional area decreases with increasing length. Since the change in value is small, the change in resistance simply by geometric deformation is small. Opening the energy bands of exfoliated perfect graphene requires applying a uniaxial strain of more than 23%. Therefore, previous research has developed a stress sensor that changes the resistance change by changing the contact area between graphene sheets. In this model, the graphene sheets are not seamlessly connected in the plane, but overlap each other to a certain extent, and the overlapping graphene part has a reduced resistance compared with a single layer. Therefore, when tensile stress and compressive stress are applied respectively, the contact area of the graphene in the overlapping part decreases and increases accordingly, thus bringing about a change in resistance. Compared with the graphene stress sensor using deformation, the sensitivity factor of the stress sensor obtained by changing the size of the contact area when applying stress can be increased to about 10-100, but the sensitivity required in the distance application still has a large Gap, and the sensitivity of the graphene stress sensor based on this principle depends to a large extent on the degree of superposition between graphene sheets, so the repeatability between different samples is not good. In addition, due to the limitation that metal electrodes are prone to fracture under large strains, the graphene artificial electronic skin using metal electrodes can withstand limited strain (<5%).

Contents of the invention

The main purpose of this application is to use the nanographene obtained by the plasma enhanced chemical vapor deposition method as the basis, and obtain graphene films with different nucleation densities by controlling different growth conditions, and use them as sensing channels based on the different tunneling effects of different films The channel and the electrode part, so as to realize the all-graphene artificial electronic skin with high transparency, high sensitivity (sensitivity factor>500) and resistance to large strain (>100%). In addition, by adjusting the growth conditions of graphene, flexible all-graphene device arrays with adjustable sensitivity and adapting to different strain environments can be obtained, thereby realizing a new type of artificial electronic skin that surpasses the tactile function of human skin, which can be used in future wearables equipment, touch screen and other fields.

In order to achieve the above object, the present invention provides the following technical solutions:

A highly sensitive all-graphene artificial electronic skin that can resist ultra-large strains, including a flexible substrate, an electrode pattern array made of low-density nucleated graphene, and a sensitive mechanical response made of high-density nucleated graphene Channel: the electrode pattern array and the channel are both arranged on the surface of the flexible substrate, and the corresponding two electrodes are connected through the channel.

Graphene films with different nucleation densities were obtained by adjusting the growth temperature of the plasma-enhanced chemical vapor deposition system. Among them, due to the obvious tunneling effect of graphene with high nucleation density, the current will change significantly with the strain under stress, so as to realize the function of mechanical sensing; the graphene obtained by low density nucleation has low resistance and tunneling The effect of the wear-through effect is not obvious, and the function of the electrode can be realized. When a large tensile stress is applied, the electrode breakage and the like are effectively avoided, ensuring the stability of the device function.

As a preferred embodiment of the above-mentioned high-sensitivity all-graphene artificial electronic skin that can resist ultra-large strain, the flexible substrate is: PET flexible substrate, PI flexible substrate, PDMS flexible substrate.

The PET flexible substrate is a polyethylene terephthalate flexible substrate. It has excellent physical and mechanical properties in a wide temperature range, and its long-term use temperature can reach 120 ° C. It has excellent electrical insulation. Even at high temperature and high frequency, its electrical properties are still good, but its corona resistance is poor. Good creep resistance, fatigue resistance, friction resistance and dimensional stability.

PI flexible substrate is a polyimide flexible substrate, which is the material with the best temperature resistance among existing polymer materials, and has excellent chemical stability and mechanical properties, so it is considered to be a class with great potential Flexible substrate material.

PDMS flexible substrate is silicone polydimethylsiloxane flexible substrate, which is convenient and easy to obtain, stable chemical properties, transparent and thermal stability, low Young's modulus, skin-friendly, and good adhesion to electronic materials Etc.

The above-mentioned high-sensitivity all-graphene artificial electronic skin that can resist super large strains, as a preferred embodiment, the low-density nucleation means that the size of the deposited graphene islands is 15nm-30nm, and the high-density nucleation It means that the size of the deposited graphene islands is 5nm-10nm.

Graphene films with different nucleation densities were obtained by adjusting the growth temperature of the plasma-enhanced chemical vapor deposition system. Among them, due to the obvious tunneling effect of graphene with high nucleation density, the current will change significantly with the strain under stress, so as to realize the function of mechanical sensing; the graphene obtained by low density nucleation has low resistance and tunneling The effect of the wear-through effect is not obvious, and the function of the electrode can be realized. When a large tensile stress is applied, the electrode breakage and the like are effectively avoided, ensuring the stability of the device function.

The second aspect of the present application provides a method for preparing an ultra-strain-resistant highly sensitive all-graphene artificial electronic skin, comprising the following steps:

(1) Deposit graphene films with different nucleation densities on silicon wafer substrates by plasma chemical vapor deposition to prepare low-density nucleation graphene films and high-density nucleation graphene films; use methane as a precursor at temperature Under the condition of 500°C-600°C, a graphene film with a thickness of 2nm is directly deposited on a silicon oxide substrate by using a plasma chemical vapor deposition system. The temperature of the deposition process is different, and the nucleation density formed is different. Higher nucleation density is greater.

(2) spin-coat PMMA on the low-density nucleation graphene film obtained in step (1), and transfer the low-density nucleation graphene film to the flexible substrate by wet etching, then remove the PMMA layer; Exposure and reactive ion etching technology to process low-density nucleated graphene film to obtain graphene electrode pattern array;

(3) spin-coat PMMA on the high-density nucleation graphene film obtained in step (1), and transfer the high-density nucleation graphene film to the flexible substrate by wet etching, then remove the PMMA layer; and utilize ultraviolet optics Exposure and reactive ion etching techniques to process high-density nucleated graphene films to obtain graphene channels.

The preparation method of the above-mentioned high-sensitivity all-graphene artificial electronic skin resistant to ultra-large strain, as a preferred embodiment, in step (1), the silicon chip base layer is a silicon chip base layer covered with a 300nm oxide layer. bottom layer.

The above-mentioned method for preparing a highly sensitive all-graphene artificial electronic skin resistant to super-large strain, as a preferred embodiment, in step (1), the temperature of vapor deposition corresponding to low-density nucleation is 510-540°C; The temperature of vapor deposition corresponding to high-density nucleation is 580-600 °C.

Above-mentioned a kind of preparation method of the highly sensitive all-graphene artificial electronic skin of anti-ultralarge strain, as a kind of preferred embodiment, in step (2) and step (3), the concentration of spin coating PMMA is 5%; The method of corrosion is: immerse in 10% hydrofluoric acid for 10 minutes.

The beneficial effect of the present invention is: the high-sensitivity all-graphene artificial electronic skin that can resist ultra-large strains in the present invention obtains graphene films with different nucleation densities by controlling different growth conditions, based on the different tunneling effects of different films as Sensing channels and electrode parts, thereby realizing an all-graphene artificial electronic skin with high transparency, high sensitivity (sensitivity factor>500) and resistance to large strains (>100%). In addition, by adjusting the growth conditions of graphene, flexible all-graphene device arrays with adjustable sensitivity and adapting to different strain environments can be obtained, thereby realizing a new type of artificial electronic skin that surpasses the tactile function of human skin, which can be used in future wearables equipment, touch screen and other fields.

The high-sensitivity all-graphene artificial electronic skin that can resist ultra-large strains of the present invention can be prepared in a large area, which provides the possibility for the processing of artificial electronic skins, and can mass-produce device arrays with stable mechanical properties, and ensures that all-graphene The artificial electronic skin can withstand ultra-large strain without breaking, which greatly improves the sensitivity factor of the graphene-based artificial electronic skin in response to external strain.

The preparation process of the high-sensitivity all-graphene artificial electronic skin that can resist ultra-large strain of the present invention is also compatible with the existing semiconductor processing technology, that is, the all-graphene artificial electronic skin of the present invention has good application potential and Wide application value.

Description of drawings

Fig. 1 is the structural diagram of the high-sensitivity all-graphene artificial electronic skin of the present invention that can resist ultra-large strain;

In the figure: 1, electrode; 2, channel; 3, flexible substrate.

Detailed ways

In order to enable those skilled in the art to better understand the solution of the present application, the technical solution in the embodiment of the application will be clearly and completely described below in conjunction with a case. Obviously, the described embodiment is only a part of the embodiment of the application. rather than all examples. Based on the embodiments in this application, all other embodiments obtained by persons of ordinary skill in the art without creative efforts shall fall within the scope of protection of this application.

Example 1

A high-sensitivity all-graphene artificial electronic skin that can resist ultra-large strains, including a PET flexible substrate, an electrode pattern array made of low-density nucleated graphene, and a sensitive mechanical response made of high-density nucleated graphene channel; the electrode pattern array and the channel are both arranged on the surface of the flexible substrate, and the corresponding two electrodes are connected through the channel;

The low-density nucleation means that the deposited graphene islands have a size of 15nm-30nm, and the high-density nucleation means that the deposited graphene islands have a size of 5nm-10nm.

The structural diagram of the all-graphene artificial electronic skin described in Example 1 of the present invention is shown in FIG. 1 .

The preparation method of the highly sensitive all-graphene artificial electronic skin that can resist ultra-large strain described in embodiment 1 comprises the following steps:

(1) Using methane as a precursor at a temperature of 500°C-600°C, a plasma chemical vapor deposition system is used to directly deposit a graphene film with a thickness of 2nm on a silicon wafer substrate covered with 300nm silicon dioxide on the surface , the temperature of the deposition process is different, and the nucleation density formed is different. The higher the temperature, the greater the nucleation density. In this embodiment, the temperature of vapor deposition corresponding to low-density nucleation is 520 ° C; The temperature of vapor deposition is 590°C;

(2) spin coating concentration is 5% PMMA on step (1) gained low-density nucleation graphene thin film, the hydrofluoric acid solution that the substrate of spin coating PMMA is placed in 10% concentration stands still 10 minutes, treats silicon dioxide The layer is completely corroded, and the PMMA film with graphene is suspended in the solution and rinsed with deionized water multiple times, then the PMMA in the solution is picked up with a flexible substrate, and then the PMMA layer is removed using acetone; and the UV optical exposure and Reactive ion etching technology processes low-density nucleated graphene films to obtain graphene electrode pattern arrays;

(3) on step (1) gained high-density nucleation graphene film, spin-coating concentration is the PMMA of 5%, the hydrofluoric acid solution that the substrate of spin-coating PMMA is placed in 10% concentration stands still 10 minutes, treats silicon dioxide The layer is completely corroded, and the PMMA film with graphene is suspended in the solution and rinsed with deionized water multiple times, then the PMMA in the solution is picked up by a flexible substrate, and the PMMA layer is removed by using acetone; Ion etching technology processes high-density nucleated graphene films to obtain graphene channels.

The transparency of the all-graphene artificial electronic skin obtained in Example 1 of the present invention is >90%, its sensitivity factor can reach more than 500, and the degree of resistance to large strains is >100%.

Example 2

A highly sensitive all-graphene artificial electronic skin that can resist ultra-large strains, including a PI flexible substrate, an electrode pattern array made of low-density nucleated graphene, and a sensitive mechanical response made of high-density nucleated graphene channel; the electrode pattern array and the channel are both arranged on the surface of the flexible substrate, and the corresponding two electrodes are connected through the channel;

The low-density nucleation means that the deposited graphene islands have a size of 15nm-30nm, and the high-density nucleation means that the deposited graphene islands have a size of 5nm-10nm.

The preparation method of the highly sensitive all-graphene artificial electronic skin that can resist ultra-large strain described in embodiment 2 comprises the following steps:

(1) Using methane as a precursor at a temperature of 500°C-600°C, a plasma chemical vapor deposition system is used to directly deposit a graphene film with a thickness of 2nm on a silicon wafer substrate covered with 300nm silicon dioxide on the surface , the temperature of the deposition process is different, and the nucleation density formed is different. The higher the temperature, the greater the nucleation density. In this embodiment, the temperature of vapor deposition corresponding to low-density nucleation is 510 ° C; The temperature of vapor deposition is 600°C;

(2) spin coating concentration is 5% PMMA on step (1) gained low-density nucleation graphene thin film, the hydrofluoric acid solution that the substrate of spin coating PMMA is placed in 10% concentration stands still 10 minutes, treats silicon dioxide The layer is completely corroded, and the PMMA film with graphene is suspended in the solution and rinsed with deionized water multiple times, then the PMMA in the solution is picked up by a flexible substrate, and the PMMA layer is removed by using acetone; Ion etching technology processes low-density nucleated graphene films to obtain graphene electrode pattern arrays;

(3) on step (1) gained high-density nucleation graphene film, spin-coating concentration is the PMMA of 5%, the hydrofluoric acid solution that the substrate of spin-coating PMMA is placed in 10% concentration stands still 10 minutes, treats silicon dioxide The layer is completely corroded, and the PMMA film with graphene is suspended in the solution and rinsed with deionized water multiple times, then the PMMA in the solution is picked up by a flexible substrate, and the PMMA layer is removed by using acetone; Ion etching technology processes high-density nucleated graphene films to obtain graphene channels.

Example 3

A highly sensitive all-graphene artificial electronic skin that can resist ultra-large strains, including PDMS flexible substrates, electrode pattern arrays made of low-density nucleated graphene, and sensitive mechanical response made of high-density nucleated graphene channel; the electrode pattern array and the channel are both arranged on the surface of the flexible substrate, and the corresponding two electrodes are connected through the channel;

The low-density nucleation refers to graphene islands with a size of 15nm-30nm, and the high-density nucleation refers to graphene islands with a size of 5nm-10nm.

The preparation method of the highly sensitive all-graphene artificial electronic skin that can resist ultra-large strain described in embodiment 3 comprises the following steps:

(1) Using methane as a precursor at a temperature of 500°C-600°C, using a plasma chemical vapor deposition system to directly deposit a graphene film with a thickness of 2nm on a silicon wafer substrate covered with 300nm silicon oxide on the surface, The temperature of the deposition process is different, and the nucleation density formed is different. The higher the temperature, the greater the nucleation density. In this embodiment, the temperature of the vapor phase deposition corresponding to the low density nucleation is 530 ° C; The deposition temperature is 580°C;

(2) spin coating concentration is 5% PMMA on step (1) gained low-density nucleation graphene thin film, the hydrofluoric acid solution that the substrate of spin coating PMMA is placed in 10% concentration stands still 10 minutes, treats silicon dioxide The layer is completely corroded, and the PMMA film with graphene is suspended in the solution and rinsed with deionized water multiple times, then the PMMA in the solution is picked up with a flexible substrate, and then the PMMA layer is removed using acetone; and the UV optical exposure and Reactive ion etching technology processes low-density nucleated graphene films to obtain graphene electrode pattern arrays;

(3) on step (1) gained high-density nucleation graphene film, spin-coating concentration is the PMMA of 5%, the hydrofluoric acid solution that the substrate of spin-coating PMMA is placed in 10% concentration stands still 10 minutes, treats silicon dioxide The layer is completely corroded, and the PMMA film with graphene is suspended in the solution and rinsed with deionized water multiple times, then the PMMA in the solution is picked up by a flexible substrate, and the PMMA layer is removed by using acetone; Ion etching technology processes high-density nucleated graphene films to obtain graphene channels.

The above is only a preferred embodiment of the present invention, it should be pointed out that for those of ordinary skill in the art, without departing from the method of the present invention, some improvements and supplements can also be made, and these improvements and supplements should also be considered Be the protection scope of the present invention.

Claims (6)

1. A highly sensitive all-graphene artificial electronic skin that can resist ultra-large strain, it is characterized in that, Including flexible substrates, electrode pattern arrays made of low-density nucleated graphene, and channels with sensitive mechanical responses made of high-density nucleated graphene; The electrode pattern array and the channel are both arranged on the surface of the flexible substrate, and the corresponding two electrodes are connected through the channel; Low-density nucleation means that the size of the deposited graphene islands is 15nm-30nm, and the high-density nucleation means that the size of the deposited graphene islands is 5nm-10nm; Low-density nucleated graphene and high-density nucleated graphene were obtained by adjusting the growth temperature of the plasma-enhanced chemical vapor deposition system, respectively. 2. according to claim 1, the highly sensitive all-graphene artificial electronic skin that can resist ultra-large strain is characterized in that, The flexible substrate is: PET flexible substrate, PI flexible substrate, PDMS flexible substrate. 3. the preparation method of the high-sensitivity all-graphene artificial electronic skin that can resist ultra-large strain described in one of claim 1-2, it is characterized in that, Include the following steps: (1) Depositing graphene films with different nucleation densities on the base layer of silicon wafers by plasma chemical vapor deposition to produce low-density nucleation graphene films and high-density nucleation graphene films; (2) spin-coat PMMA on the low-density nucleation graphene film obtained in step (1), and transfer the low-density nucleation graphene film to the flexible substrate by wet etching, then remove the PMMA layer; Exposure and reactive ion etching technology to process low-density nucleated graphene film to obtain graphene electrode pattern array; (3) spin-coat PMMA on the high-density nucleation graphene film obtained in step (1), and transfer the high-density nucleation graphene film to the flexible substrate by wet etching, then remove the PMMA layer; and utilize ultraviolet optics Exposure and reactive ion etching techniques to process high-density nucleated graphene films to obtain graphene channels. 4. the preparation method of the highly sensitive all-graphene artificial electronic skin that can resist ultra-large strain according to claim 3, is characterized in that, In step (1), the silicon wafer base layer is a silicon wafer base layer covered with a 300nm oxide layer. 5. the preparation method of the highly sensitive all-graphene artificial electronic skin that can resist ultra-large strain according to claim 3, is characterized in that, In step (1), the temperature of vapor deposition corresponding to low-density nucleation is 510-540°C; the temperature of vapor deposition corresponding to high-density nucleation is 580-600°C. 6. the preparation method of the highly sensitive all-graphene artificial electronic skin that can resist ultra-large strain according to claim 3, is characterized in that, In step (2) and step (3), the concentration of the spin-coated PMMA is 5%; the wet etching is: soaking with 10% hydrofluoric acid for 10 minutes.

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