Flexible graphene sensing electrode laser-induced fusion atomic layer deposition method

Abstract

The invention discloses a laser-induced fusion atomic layer deposition method for a flexible graphene sensing electrode, which belongs to the field of micro-nano manufacturing and specifically comprises four procedures of laser induction, three-dimensional atomic layer deposition, flexible transfer printing and electrode assembly. Firstly, three-dimensional porous graphene grows on a polyimide film through laser induction, and then a gas-phase precursor is allowed to alternately enter a porous graphene framework and be continuously deposited on hole walls by utilizing the self-limiting layer-by-layer growth characteristic of atomic layer deposition, so that a conductive metal atomic layer covering in a full-step manner is formed; and finally, through liquid silica gel pouring-curing stripping, transferring the porous graphene / metal atomic layer to a flexible substrate, and carrying out electrode packaging. The nano-scale metal atomic layers are in interface contact / disconnection, the micron-scale graphene framework is in bridge connection with the atomic layers at the interface, the functions are different and have complementary advantages, the piezoresistive synergistic effect is contributed under the micro-nano scale, and the sensitivity and the response range of the flexible graphene-based sensing electrode are remarkably enhanced.

Description

Technical Field

[0001] The invention belongs to the field of micro-nano manufacturing technology, and specifically relates to a laser-induced fusion atomic layer deposition method for a flexible graphene sensing electrode. Background Art

[0002] With the rapid development of emerging technology fields such as medical health, intelligent sensing, and flexible electronics, there is an increasingly urgent demand for flexible micro-nano sensing components in my country. The new generation of flexible sensing electrodes with micro-nano scale is the basic component of flexible sensor devices and even back-end wearable health monitoring equipment, and is also an essential part of human-computer interaction / intelligence and telemedicine. Graphene is an effective carrier for large-scale application of flexible sensing components. Porous graphene is generated from polyimide (PI) film by laser induction and can be transferred to a stretchable substrate through a simple casting-peeling step. It has broad application prospects in the field of flexible sensing. However, it is still difficult to further improve the sensing performance of the assembled device, especially the sensitivity and response range, relying solely on the three-dimensional porous structure of laser-induced graphene.

[0003] In order to solve the above problems, it is necessary to design a laser-induced fusion atomic layer deposition method for flexible graphene sensing electrodes. The present invention is different from the conventional idea of ​​traditional laser-induced graphene in-situ doping of nano-metal particles, and abandons the random and uneven distribution of nanoparticles generated by laser in-situ reaction, and the drawbacks of being unable to achieve full step coverage; focusing on the unique self-limiting layer-by-layer growth characteristics of atomic layer deposition, by continuously depositing conformal nanoscale conductive metal atomic layers on laser-induced micron-scale three-dimensional porous graphene, through the dynamic contact between the nanoscale metal atomic layers and the layer interface, and the working principle of the micron-scale graphene skeleton as support, a flexible graphene-based sensing electrode with both high sensitivity and wide response range is prepared.

[0004] Chinese invention patent CN201610228290.4 discloses a method for preparing graphene nanocomposite energetic materials using atomic layer deposition technology. The invention uses gas phase atomic layer deposition technology to allow two different precursors to alternately pass through the reaction chamber and react chemically with graphene / nanometal composite powders, thereby achieving uniform coating of oxides on the graphene surface and nanometal surface, respectively. However, the substrate used in the invention is an ultrasonic-assisted solution mixing and in-situ reduction method to prepare graphene / nanometal composite powders, and does not involve laser induction and flexible transfer processes. The present invention uses three-dimensional porous graphene with laser-induced micron-sized holes as a loading skeleton, and cleverly utilizes the holes generated by gas escape during laser induction as natural entry and exit channels for gaseous precursors and inert gases in the atomic layer deposition process, and deposits a nanoscale conductive metal atomic layer with full step coverage on the micron-sized three-dimensional porous graphene skeleton. After further flexible transfer, the three-dimensional porous graphene contributes to the interface piezoresistive effect at different micro-nano scales due to continuous atomic layer deposition, and is expected to be applied in the field of flexible sensing, with the aim of improving the piezoresistive effect and sensing performance of the flexible electrode.

[0005] Chinese invention patent CN202310842982.8 discloses a core-shell structure high temperature resistant wave absorbing material and its preparation method and application, by ultrasonically dispersing the reduced graphene oxide in ethanol and dripping it onto the surface of a quartz sheet, and then using trimethylaluminum and deionized water as precursors for atomic layer deposition, transferring it to a closed hot wall atomic layer deposition reactor, and controlling the pulse time, deposition temperature and number of precursor cycles to achieve precise control of the thickness of the deposited layer. However, the reduced graphene used in the invention has no special structure, only a deposited layer with a surface nanometer thickness, and is applied to the field of high temperature wave absorption. The present invention uses laser-induced three-dimensional porous graphene as a skeleton, covers a nanometer-scale conductive metal atomic layer in micrometer-scale holes, and prepares a graphene-based sensing electrode by flexible transfer. The electrode is based on the three-dimensional conformal construction capability of atomic layer deposition technology. The metal atomic layer is fully stepped on the graphene skeleton plane and the internal pore wall, and the micrometer-scale graphene skeleton and its nanometer-scale metal atomic layer are used as sensitive materials to jointly improve the sensing performance of the flexible electrode, which is applied in micro-nano sensing, flexible electronics, and medical health fields. Summary of the invention

[0006] The purpose of the present invention is to address the shortcomings of the prior art and provide a method for laser-induced fusion atomic layer deposition of flexible graphene sensing electrodes. The method mainly utilizes the three-dimensional conformal construction capability of atomic layer deposition technology to fully step-cover the nanoscale metal atomic layer inside the laser-induced micron-scale three-dimensional porous graphene, and improves the sensitivity and response range of the flexible graphene-based sensing electrode through the interface piezoresistive effect at different micro-nano scales.

[0007] The above technical objectives of the present invention are achieved through the following technical solutions: A method for laser-induced fusion atomic layer deposition of flexible graphene sensing electrodes, characterized in that it includes four processes: laser induction, three-dimensional atomic layer deposition, flexible transfer and electrode assembly;

[0008] S1 Laser Induction: Using continuous CO2 laser to induce the growth of three-dimensional porous graphene with micrometer-sized holes on polyimide film as a skeleton carrier for metal atomic layer deposition;

[0009] S2 3D atomic layer deposition: Using an atomic layer deposition system, the natural holes generated by laser-induced graphene escape are used as gas channels, and the first gas phase precursor, inert gas, second gas phase precursor, and inert gas are alternately introduced to produce gas-solid phase chemical adsorption reactions, thereby depositing a fully stepped nanoscale conductive metal atomic layer on the micron-scale three-dimensional porous graphene skeleton;

[0010] S3 flexible transfer: Pour liquid silicone into the three-dimensional porous graphene skeleton with a conductive metal atomic layer attached, perform room temperature curing and low temperature peeling, and transfer the micron-scale three-dimensional porous graphene skeleton / nanoscale metal atomic layer to the flexible substrate;

[0011] S4 electrode assembly: After connecting both ends of the flexible electrode of the three-dimensional porous graphene / nanoscale metal atomic layer to the conductive copper wire, it is placed in a mold and poured with liquid silicone for further curing and encapsulation.

[0012] Specifically, according to the laser induced fusion atomic layer deposition method for a flexible graphene sensor electrode as described in claim 1, in the S1 laser induction process, the micron-sized holes of the three-dimensional porous graphene serve as natural inlet and outlet channels for gaseous precursors and inert gases in the S2 three-dimensional atomic layer deposition process, and also as natural entry channels for liquid silicone in the S3 flexible transfer process.

[0013] Specifically, according to the laser induced fusion atomic layer deposition method for a flexible graphene sensor electrode as described in claim 1, in the S2 three-dimensional atomic layer deposition process, the thickness of the nanoscale conductive metal atomic layer is 1 to 10 nm, covering the holes of the micron-scale three-dimensional porous graphene with a pore size of 1 to 5 μm.

[0014] Specifically, according to the laser induced fusion atomic layer deposition method for a flexible graphene sensor electrode as described in claim 1, in the S1 laser induction process, the processing parameters are controlled to be an output power of 2 to 4 W, a scanning rate of 10 to 200 mm / s, and a focal length of -2 to 2 mm.

[0015] Specifically, according to the laser induced fusion atomic layer deposition method for a flexible graphene sensor electrode according to claim 1, the conductive metal atomic layer in the S2 three-dimensional atomic layer deposition process refers to one or more of Pt, Fe, Al, and Cu.

[0016] Specifically, according to the laser induced fusion atomic layer deposition method for a flexible graphene sensor electrode as described in claim 1, the first gas phase precursor of the S2 three-dimensional atomic layer deposition process refers to one or more of halides, alkoxides, alkyl compounds, cyclopentadienyl compounds, and diketone compounds.

[0017] Specifically, according to the laser induced fusion atomic layer deposition method for a flexible graphene sensor electrode as described in claim 1, in the S2 three-dimensional atomic layer deposition process, the temperature of the gas phase precursor is alternately introduced at 100°C to 300°C, and the number of times is 100 to 1000 times.

[0018] Specifically, according to the laser induced fusion atomic layer deposition method for a flexible graphene sensor electrode described in claim 1, the room temperature curing in the S3 flexible transfer process refers to the curing and molding of the Ecoflex prepolymer at 25°C for 48 to 64 hours to avoid high-temperature oxidation of the nanoscale conductive metal atomic layer.

[0019] Specifically, according to the laser induced fusion atomic layer deposition method for a flexible graphene sensing electrode described in claim 1, the low-temperature peeling in the S3 flexible transfer process refers to refrigerating the three-dimensional porous graphene skeleton / metal atomic layer after solidification at a low temperature of 2 to 8°C for 30 minutes, and then peeling and transferring it to a silica gel substrate to avoid phase separation between the graphene skeleton and the metal atomic layer.

[0020] Compared with the existing technology, the above-mentioned flexible graphene sensing electrode laser induced fusion atomic layer deposition method has the following beneficial effects:

[0021] ① Low cost and efficient processing: The three processes of laser processing, atomic layer deposition and flexible transfer have good continuity with each other. The formation of the three-dimensional porous structure of the laser-induced graphene electrode originates from the gas escape behavior, which means that the entire skeleton is three-dimensionally connected. During atomic layer deposition, the gas precursor and the inert gas are allowed to alternately enter the three-dimensional porous graphene skeleton and continuously deposit on the surface of the pore wall, and then a gas-solid chemical adsorption reaction occurs to form a fully stepped conductive metal atomic layer. During flexible transfer, it is beneficial for liquid silicone to enter the three-dimensional porous graphene / conductive metal atomic layer, and after curing and peeling, a flexible graphene-based sensing electrode can be formed.

[0022] ② Considering both sensitivity and response range: Electrode structures of different dimensions at micro-nano scales, surfaces and inside contribute to the interface piezoresistance effect. The dynamic and reversible contact / disconnection between nano-metal atomic layers causes a sharp change in the electrical signal. After the micron graphene skeleton is filled with silicone, it bridges the atomic layers at the interface with its own adaptability and reconfigurability. The different functions complement each other's advantages. Since the interface piezoresistance effect at different micro-nano scales is strengthened, the flexible sensing electrode has both high sensitivity and a wide response range. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a schematic diagram of processing of laser-induced fusion atomic layer deposition of flexible graphene-based sensing electrodes in the present invention;

[0024] Figure 2 is a schematic diagram of laser-induced atomic layer deposition of three-dimensional porous graphene in the present invention;

[0025] Figure 3 It is a schematic diagram of the interface piezoresistance principle of the flexible graphene-based sensing electrode in the present invention;

[0026] Figure 4 is a surface morphology diagram of the flexible graphene-based sensing electrode in the present invention;

[0027] Figure 5 is a resistance response curve of the flexible graphene-based sensing electrode of the present invention under a maximum pressure of 180 kPa; DETAILED DESCRIPTION

[0028] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are described in detail below in conjunction with the accompanying drawings. In the following description, many specific details are set forth to facilitate a full understanding of the present application. However, the present application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without violating the connotation of the present application, so the present application is not limited by the specific embodiments disclosed below.

[0029] The problem that the sensing performance, especially the sensitivity and response range, of laser-induced graphene-based flexible electrodes is still difficult to be further improved by relying solely on three-dimensional porous structures is solved. The present invention focuses on the unique self-limited layer-by-layer growth characteristics of atomic layer deposition, and continuously deposits conformal nanoscale conductive metal atomic layers on laser-induced micron-scale three-dimensional porous graphene, through the dynamic contact between the nanoscale metal atomic layers and the layer interface, and the micron-scale graphene skeleton is filled with silica gel as a support to prepare a flexible graphene-based sensing electrode with both high sensitivity and wide response range.

[0030] like Figure 1 and 2As shown, the flexible graphene sensing electrode laser induced fusion atomic layer deposition method is characterized by comprising four steps of laser induction, three-dimensional atomic layer deposition, flexible transfer and electrode assembly;

[0031] S1 Laser Induction: Using continuous CO2 laser to induce the growth of three-dimensional porous graphene with micrometer-sized holes on polyimide film as a skeleton carrier for metal atomic layer deposition;

[0032] S2 3D atomic layer deposition: Using an atomic layer deposition system, the natural holes generated by laser-induced graphene escape are used as gas channels, and the first gas phase precursor, inert gas, second gas phase precursor, and inert gas are alternately introduced to produce gas-solid phase chemical adsorption reactions, thereby depositing a fully stepped nanoscale conductive metal atomic layer on the micron-scale three-dimensional porous graphene skeleton;

[0033] S3 flexible transfer: Pour liquid silicone into the three-dimensional porous graphene skeleton with a conductive metal atomic layer attached, perform room temperature curing and low temperature peeling, and transfer the micron-scale three-dimensional porous graphene skeleton / nanoscale metal atomic layer to the flexible substrate;

[0034] S4 electrode assembly: After connecting both ends of the flexible electrode of the three-dimensional porous graphene / nanoscale metal atomic layer to the conductive copper wire, it is placed in a mold and poured with liquid silicone for further curing and encapsulation.

[0035] Furthermore, in the S1 laser induction process, the micron-sized holes of the three-dimensional porous graphene serve as natural inlet and outlet channels for gaseous precursors and inert gases in the S2 three-dimensional atomic layer deposition process, and also as natural inlet channels for liquid silicone in the S3 flexible transfer process.

[0036] Furthermore, in the S2 three-dimensional atomic layer deposition process, the thickness of the nano-scale conductive metal atomic layer is 1 to 10 nm, covering the holes of the micron-scale three-dimensional porous graphene with an aperture size of 1 to 5 μm.

[0037] Furthermore, in the S1 laser induction process, the processing parameters are controlled to be an output power of 2 to 4 W, a scanning rate of 10 to 200 mm / s, and a focal length of -2 to 2 mm.

[0038] Furthermore, the conductive metal atomic layer in the S2 three-dimensional atomic layer deposition process refers to one or more of Pt, Fe, Al, and Cu.

[0039] Furthermore, the first gas-phase precursor of the S2 three-dimensional atomic layer deposition process refers to one or more of halides, alkoxides, alkyl compounds, cyclopentadienyl compounds, and diketone compounds.

[0040] Furthermore, in the S2 three-dimensional atomic layer deposition process, the temperature of the gas phase precursor is alternately introduced at 100° C. to 300° C., and the number of times is 100 to 1000 times.

[0041] Furthermore, the room temperature curing in the S3 flexible transfer process refers to curing the Ecoflex prepolymer at 25° C. for 48 to 64 hours to prevent high temperature oxidation of the nano-scale conductive metal atomic layer.

[0042] Furthermore, the low-temperature peeling in the S3 flexible transfer process refers to refrigerating the three-dimensional porous graphene skeleton / metal atomic layer after solidification at a low temperature of 2 to 8°C for 30 minutes, and then peeling and transferring it to a silica gel substrate to prevent phase separation between the graphene skeleton and the metal atomic layer.

[0043] like Figure 3 As shown, the working principle of the present invention is that the laser-induced porous graphene electrode has a dual effect of structural-functional integration in atomic layer deposition. First, the laser-induced porous graphene electrode is used as a natural skeleton, and the "one-in-one-out" of gas is used to achieve nano-scale atomic layer thickness control on the hole surface. The formation of the laser-induced porous graphene electrode originates from the gas escape behavior, which means that the entire skeleton is three-dimensionally connected inside, allowing the gas-phase precursor to alternately enter the porous graphene skeleton and continuously deposit on the pore wall surface during atomic layer deposition, and then a gas-solid chemical adsorption reaction occurs to form a fully step-covered conductive metal atomic layer (see Figure 4 ); secondly, after casting-peeling transfer to a flexible substrate, the porous graphene skeleton achieves an enhanced interface piezoresistance effect due to continuous atomic layer deposition. The dynamic and reversible contact / disconnection between the nano-metal atomic layer and the layer interface causes a sharp change in the electrical signal, and after the micron graphene skeleton is filled with silica gel, it bridges the atomic layer at the interface with its own adaptability and reconfigurability. The different functions and advantages of each other complement each other, and the interface piezoresistance effect of the device at different micro-nano scales is enhanced.

[0044] like Figure 5 As shown, through the interface piezoresistance effect between the micron graphene skeleton and the nano-metal atomic layer, the highest sensitivity of the flexible graphene-based sensing electrode is 15.12 kPa -1 , the maximum response range reaches 180 kPa, while the maximum sensitivity of graphene-based flexible electrodes prepared by pure laser induction and transfer printing is only 2.84 kPa -1 , the maximum response range is 180 kPa. Therefore, the sensitivity of the flexible sensing electrode of the present invention is increased by 5.3 times without sacrificing the response range, and has the effects of high sensitivity and wide response range.

[0045] The contents explained in the above embodiments should be understood as these embodiments are only used to more clearly illustrate the present invention, and are not used to limit the scope of the present invention. After reading the present invention, various equivalent forms of modifications to the present invention by those skilled in the art all fall within the scope defined by the claims attached to this application.

Claims

1. A method for laser-induced fusion atomic layer deposition of flexible graphene sensing electrodes, characterized in that: It includes four processes: laser induction, three-dimensional atomic layer deposition, flexible transfer and electrode assembly; S1 Laser Induction: Using continuous CO2 laser to induce the growth of three-dimensional porous graphene with micrometer-sized holes on polyimide film as a skeleton carrier for metal atomic layer deposition; S2 3D atomic layer deposition: Using an atomic layer deposition system, the natural holes generated by laser-induced graphene escape are used as gas channels, and the first gas phase precursor, inert gas, second gas phase precursor and inert gas are alternately introduced to produce gas-solid phase chemical adsorption reactions, thereby depositing a fully stepped nanoscale conductive metal atomic layer on the micron-scale three-dimensional porous graphene skeleton; S3 flexible transfer: After pouring liquid silicone into the three-dimensional porous graphene skeleton with a conductive metal atomic layer attached, it is cured at room temperature and peeled off at low temperature to transfer the micron-scale three-dimensional porous graphene skeleton / nanoscale metal atomic layer to the flexible substrate; S4 electrode assembly: After connecting both ends of the flexible electrode of the three-dimensional porous graphene / nanoscale metal atomic layer to the conductive copper wire, it is placed in a mold and poured with liquid silicone for further curing and encapsulation.

2. According to the laser induced fusion atomic layer deposition method of a flexible graphene sensor electrode as described in claim 1, in the S1 laser induction process, the micron-sized holes of the three-dimensional porous graphene serve as natural inlet and outlet channels for gaseous precursors and inert gases in the S2 three-dimensional atomic layer deposition process, and also as natural entry channels for liquid silicone in the S3 flexible transfer process.

3. According to the laser induced fusion atomic layer deposition method of a flexible graphene sensor electrode as described in claim 1, in the S2 three-dimensional atomic layer deposition process, the thickness of the nanoscale conductive metal atomic layer is 1 to 10 nm, covering the holes of the micron-scale three-dimensional porous graphene with an aperture size of 1 to 5 μm.

4. According to the method for laser-induced fusion atomic layer deposition of a flexible graphene sensing electrode as described in claim 1, in the S1 laser induction process, the control processing parameters are output power of 2 to 4 W, scanning rate of 10 to 200 mm / s, and focal length of -2 to 2 mm.

5. According to the laser induced fusion atomic layer deposition method for a flexible graphene sensor electrode as described in claim 1, the conductive metal atomic layer in the S2 three-dimensional atomic layer deposition process refers to one or more of Pt, Fe, Al, and Cu.

6. According to the laser induced fusion atomic layer deposition method for a flexible graphene sensor electrode as described in claim 1, the first gas phase precursor of the S2 three-dimensional atomic layer deposition process refers to one or more of halides, alkoxides, alkyl compounds, cyclopentadienyl compounds, and diketone compounds.

7. According to the method for laser induced fusion atomic layer deposition of a flexible graphene sensor electrode as described in claim 1, in the S2 three-dimensional atomic layer deposition process, the temperature of the gas phase precursor is alternately introduced at 100°C to 300°C, and the number of times is 100 to 1000 times.

8. According to the laser induced fusion atomic layer deposition method for a flexible graphene sensor electrode as described in claim 1, the room temperature curing in the S3 flexible transfer process refers to curing and molding the Ecoflex prepolymer at 25°C for 48 to 64 hours to avoid high temperature oxidation of the nano-scale conductive metal atomic layer.

9. According to the laser induced fusion atomic layer deposition method for a flexible graphene sensing electrode as described in claim 1, the low-temperature peeling in the S3 flexible transfer process refers to refrigerating the three-dimensional porous graphene skeleton / metal atomic layer after solidification at a low temperature of 2 to 8°C for 30 minutes, and then peeling and transferring it to a silica gel substrate to avoid phase separation between the graphene skeleton and the metal atomic layer.

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