Method for preparing carbon-based device array on polyimide material and application thereof

Abstract

The invention discloses a method for preparing a carbon-based device array on a polyimide material and application of the carbon-based device array, and belongs to the field of wearable electronics. On the basis of the laser direct writing technology, an LIG material device structure distributed in an array mode is formed on the surface of the PI material, a micro-necking structure is introduced into the device, the nanometer gaps are formed, data storage is achieved by controlling opening / closing of the nanometer gaps, opening / closing of the nanometer gaps can be controlled through an electric field or laser, the technology is simple and reliable, and the method is suitable for large-scale production. And no complex material combination is needed. The applicable PI material forms comprise fabrics, plastics or paper and the like, the nonvolatile memory array with the switch ratio up to 108 can be obtained by adopting the method, compared with the prior art, the problem of large-scale preparation of high-performance, stable and durable devices on the rough or uneven PI material surface is solved, and the method is suitable for large-scale production of the high-performance, stable and durable devices. And a technical foundation is laid for development and application of flexible wearable electronic devices.

Description

Technical Field

[0001] The present invention belongs to the field of textile electronics, and particularly relates to a method for fabricating a carbon-based device array on a polyimide (PI) material and its applications. Background Art

[0002] Electronic textile devices can be seamlessly integrated into textiles, and have great application potential in the fields of healthcare, personalized medicine, and human-computer interaction. Their advantages lie in enabling distributed data processing, enhancing privacy protection, and promoting the development of consumer electronics, adaptive fashion, and Internet of Things (IoT) systems, laying the foundation for the next generation of intelligent wearable technologies.

[0003] Despite the broad prospects, current textile storage technologies still face many challenges before widespread application. The most important ones are three aspects of problems: (1) Large-scale fabrication problem: Due to the rough and uneven surface of the fabric, traditional planar lithography processes cannot be used to fabricate devices or device arrays, which limits the batch manufacturing ability of textile devices. (2) Durability problem of devices: Whether the devices are fabricated by techniques such as direct adhesion, embedding in fibers, or using a cross-grid structure, these textile devices are prone to wear under repeated bending, folding, and friction, and performance degradation will occur. In addition, for devices made using a cross-grid structure, signal crosstalk problems will occur, thus reducing the reliability of the devices. (3) Comfort problem caused by textile devices: The introduction of non-textile materials such as metals, oxides, and two-dimensional nanostructured materials in the devices will affect the comfort and breathability of the fabric. Solving the above problems is crucial for realizing textile storage devices and promoting their applications in various related fields. Summary of the Invention

[0004] The present invention proposes a method and application for fabricating a carbon-based device array on a polyimide (PI) material. Based on the CO2 pulsed laser direct writing process, the laser energy density and scanning path are precisely controlled on the surface of the PI fabric, enabling local carbonization of the fabric to form a conductive laser-induced graphene (LIG) material. Combining with a microconstriction structure, the fabrication of the carbon-based device array is achieved.

[0005] The technical solution provided by the present invention is as follows:

[0006] A method for fabricating a carbon-based device array on a polyimide material, the steps of which include:

[0007] 1) Making an array pattern, wherein the devices in the array are distributed in a two-dimensional array, and the planar shape of each device is dumbbell-shaped; all the devices are two-terminal devices, that is, the two ends of the device are electrodes, and the middle slender part connecting the electrodes is a conductive channel. A gap region is arranged in the middle of the conductive channel of each device, and the size of the gap region is 25 - 50 μm;

[0008] 2) Using a polyimide material as the substrate, lay the polyimide material flat on the laser processing platform. At the same time, import the array pattern in step 1) into the laser control software. The laser scans the polyimide material according to the array pattern by means of a stepwise laser pulse.

[0009] 3) Under the action of the pulsed laser, the polyimide material is carbonized to form carbonized spots. The electrodes and conductive channel materials of the device are transformed from the polyimide material into laser-induced graphene materials. In the gap region in the conductive channel, due to the lack of some carbonized spots caused by the laser pulse, a microconstriction structure is formed, thereby constituting a carbon-based device based on the microconstriction structure embedded on the surface of the polyimide material, and finally completing the preparation of the carbon-based device array.

[0010] Furthermore, the polyimide material adopts PI fabric, PI plastic, and PI paper surface. Among them, PI fabric has the same excellent thermal stability as PI film and better mechanical flexibility. In addition, due to the inherent characteristics of the loose structure (which can reduce the stress concentration phenomenon during the laser ablation process) and high compliance of PI fabric, it becomes an ideal flexible substrate material. Most importantly, PI fabric is more suitable for wearable application scenarios and is the optimal solution for wearable storage devices.

[0011] Furthermore, the length of the conductive channel of the device is 25 μm - 2000 μm, and the width is 15 μm - 2000 μm.

[0012] Furthermore, the parameters of the laser are: laser power (P = 5W - 50W), PPI = 300 - 2000.

[0013] The present invention further provides a method for realizing data storage by using a carbon-based device array, and its steps include the following:

[0014] 1) Prepare an array of carbon-based devices on the polyimide material.

[0015] 2) Perform a voltage scan on the electrodes of all carbon-based devices in the array, that is, slowly increase the bias voltage. The microconstriction structure of the carbon-based device breaks to form a nano-gap. At this time, the carbon-based device is in a high-resistance state, forming an initialized memory array.

[0016] 3) Adjust the state of the devices in the memory array from the high-resistance state to the low-resistance state. The nano-gap of the conductive channel of the device is closed, which is the "1" state for data storage; keep the state of the devices in the memory array as the high-resistance state, and the nano-gap of the conductive channel of the device is disconnected, which is the "0" state for data storage.

[0017] Furthermore, the state of the device is adjusted from the high-resistance state to the low-resistance state by applying a scan voltage to the device in a current-limiting state.

[0018] Furthermore, the state of the device is adjusted from a high-resistance state to a low-resistance state by applying laser irradiation above the device.

[0019] The beneficial effects of the present invention are as follows:

[0020] The present invention adopts the laser direct writing technology, without lithography and without special parameter adjustment of the laser. It only needs to complete the laser direct writing according to the design layout. In the specific processing process, due to the instantaneous carbonization process of the PI material under the action of pulsed laser, which will cause the expansion of the LIG material, even if some carbonization spots are missing in the gap area, the LIG material is not completely disconnected, forming point contact of the LIG material, so as to obtain a microscale neck structure based on the LIG material and realize a carbon-based device array based on the microscale neck structure.

[0021] Furthermore, by applying a gradually increasing bias voltage to the device, due to the uneven distribution of the conductive material at the microscale neck structure, Joule heat accumulation occurs, resulting in a rapid increase in the local temperature until it exceeds the threshold that the carbon-carbon bond can withstand and breaks, so that the width of the microscale neck structure gradually decreases, and finally a nano-gap is formed. Using the nano-gap in the open or closed state for the "1" state or "0" state of data storage.

[0022] Using the present invention, a high-performance device with a switching ratio as high as 10 8 and a write / erase cycle life exceeding 10,000 times and a retention time exceeding 10 4 s is constructed. It is more accurate than the traditional method, and the customized processing of the device is realized through laser direct writing, which simplifies the process flow. At the same time, due to the high conductivity and flexibility of the LIG material, the memory has excellent mechanical durability and stability.

[0023] The present invention has the advantages of ultra-low power consumption, high integration, and compatibility with the traditional CMOS process, providing strong support for the integration of subsequent intelligent wearable devices and flexible electronic devices. Brief Description of the Drawings

[0024] Figure 1 It is a design and processing schematic diagram of preparing a carbon-based device on a fabric for a specific embodiment. (a) The layout of the device array designed by CAD. The inset shows the design details of a single device. The device is dumbbell-shaped, with square electrodes with a side length of 300 μm at both ends and a conductive channel with a length of 600 μm and a width of 50 μm in the middle. A 25-μm gap is provided in the middle of the conductive channel for the processing of the microscale neck structure. (b) Schematic diagram of laser direct writing processing of the fabric device;

[0025] Figure 2Morphology of the device array for specific embodiments. (a) Physical photo of the device array prepared on a PI fabric. (b) Environmental scanning electron microscope (ESEM) image of a single device after magnification, where the PI fabric is carbonized after laser ablation. (c) ESEM image of the LIG material embedded inside the PI fabric and bonded to the fibers, with the carbonized and non-carbonized parts of the fibers tightly bonded. (d) ESEM image of the porous structure of the LIG material;

[0026] Figure 3 Schematic diagram of the principle of the microconstriction structure for specific embodiments. (a) Design details of a single device: The device is dumbbell-shaped, with a conductive channel in the middle that is 500 μm - 1000 μm long and 25 μm - 1000 μm wide, and a 25-μm gap is preset in the middle of the conductive channel for processing the microconstriction structure. (b) Schematic diagram of the distribution of carbonized spots during pulsed laser processing. Region A shows continuous pulsed carbonized spots, and region B shows the absence of carbonized spots at the gap position. (c) Schematic diagram of the LIG wire and the microconstriction structure. The blue dashed box shows the continuous and dense wire, and the red dashed box shows the microconstriction region caused by the absence of carbonized spots due to laser pulses;

[0027] Figure 4 Schematic diagram of the microconstriction structure for specific embodiments. (a) Schematic diagram of the device array based on a PI fabric and its microconstriction structure, with the inset showing the laser processing schematic diagram. (b) Characterization diagram of the microconstriction structure of the LIG material based on a PI film, showing the local morphology of the microconstriction structure; (c) ESEM magnification of a single device based on a PI fabric. (d) A single device based on a PI plastic and (e) ESEM magnification view of the microconstriction part on the conductive channel;

[0028] Figure 5 Schematic diagram of the initialization process of the carbon-based device: Steps from the original state to the storage state formation.

[0029] Figure 6 I-V curve of the initialization operation and ESEM images of the device in specific embodiments. (a) Local thermal breakdown and spark discharge phenomena occurring in the microconstriction region during breakdown ablation. (b) I-V curve during the first voltage scan. (c) At the read voltage V READ = 1 V, the device current remains in the μA range, indicating that the device is not completely disconnected and the nano-gap has not formed. (d) ESEM image after the first breakdown. (e) I-V curve recorded during the second voltage scan. (f) At V READ = 1 V, the measured current drops to the pA range, and the formation of the nano-gap marks the completion of the initialization operation. (g) ESEM image after the second breakdown. (h) When the voltage scan reaches 20 V, the device enters the conduction state. (i) At V READThe current read at 1 V returns to the μA level, indicating that the carbon atom chains on both sides of the nanogap are bridged to form a conductive channel.

[0030] Figure 7 For the SET and RESET operations of the carbon-based device in the specific embodiment under electric field control. (a) I-V curves of the SET operation in 50 write / erase cycles. (b) Read current V READ = Low-resistance state current at 1 V. (c) I-V curves of the RESET operation in 50 write / erase cycles; the inset shows that the low-resistance state conductance value read during the device switching process is near 1G0. (d) Read current V READ = Current in the high-resistance state at 1 V.

[0031] Figure 8 For the current change of the device in the specific embodiment under laser irradiation. (a) Schematic diagram of the optical test of the device. (b) Relationship between laser power and current: the current of the device increases sharply when the laser power is 100 mW, and the device returns to the high-resistance state after removing the laser. (c) Response to lasers of different wavelengths: the device is equally sensitive to 650 nm, 520 nm, and 450 nm lasers. (d) The shortest optical response time of the device is 40 ms. (e) When the pulsed laser power slowly increases to 300 mW, the device realizes the optically controlled non-volatile storage function. (f) Optically controlled non-volatile storage of the device at an independent laser pulse power of 300 mW; the inset is the current reading at V READ = 1 V, showing a switching ratio as high as 10 8 .

[0032] Figure 9 For the test device diagram and actual photos of the device when the PI fabric substrate in the specific embodiment is bent. (a) The PI fabric substrate with the fabric device attached to the surface of a semi-cylindrical plastic mold for electrical testing; (b) Actual photo of the fabric device bent with the substrate.

[0033] Figure 10 For the performance change of the device in the specific embodiment before and after bending. (a) Comparison of I-V curves of the RESET operation and (b) SET operation, red for before bending and blue for after bending. (c) Change in the switching ratio of the device before and after bending. (d) Write / erase cycle test of the fabric device under bending conditions, and the switching ratio of the device is greater than 10 during the test 8 . Specific embodiments

[0034] The present invention will be further described below by way of examples of fabric memory preparation. It should be noted that the purpose of disclosing the embodiments is to help further understand the present invention. However, those skilled in the art can understand that various substitutions and modifications are possible without departing from the spirit and scope of the present invention and the appended claims. Therefore, the present invention should not be limited to the content disclosed in the embodiments, and the scope of protection claimed by the present invention shall be subject to the scope defined by the claims.

[0035] In a specific embodiment of the present invention, the polyimide material uses PI fabric. This fabric selects plain weave fabric material, with a thickness of about 500 μm and a unit area weight of 180 g / m 2 , and the linear mass density of the fiber is about 0.127 g / m –1 , provided by Changchun Gaoqi Polyimide Materials Co., Ltd., China. As a precursor for laser-induced graphene materials, PI fabric has good thermal and mechanical properties. The commercial PI fabric is washed with deionized water and dried. After completing the design of the device and its array, the PI fabric is fixed on a flat laser processing platform as the substrate and raw material to prevent substrate deformation during processing. At the same time, the height of the processing platform is adjusted to coordinate the laser focal length to ensure the smallest laser beam spot and the highest energy density during processing.

[0036] The method for preparing a carbon-based device array on a polyimide material according to the present invention comprises the steps of:

[0037] (1) Array pattern design: Use CAD software to design the required pattern. The complexity of the pattern can be adjusted according to application requirements, from simple straight lines to complex geometric shapes. The designed pattern file needs to be converted into a format suitable for the laser system, such as DXF or G-code file, which is the layout of the device array designed by CAD, as Figure 1 (a). Among them, the design details of a single device are as Figure 1 (a) shown in the illustration. The device designed by the present invention is a two-terminal device, and its shape is designed as a dumbbell shape: the square areas with side lengths of 300 μm on both sides are used as device lead electrodes, which are convenient for pinning during experimental testing. The length between the electrodes is 600 μm, and the black line with a width of 50 μm is used as the conductive channel of the device to connect the two ends of the electrodes. A gap area is set in the middle of the conductive channel of each device, and the size of this gap area is 25 - 50 μm.

[0038] (2) Laser processing setting: Import the designed pattern file into the control software of the laser system, set the laser parameters (P = 14 W; PPI = 1000), and start laser processing. As Figure 1(b) shows the schematic diagram for fabricating the device array based on the PI fabric. The inset shows the details of laser processing and the enlarged view of the device. The laser beam scans the PI fabric according to the preset pattern and path. Under the action of the laser, the local area of the PI fabric rapidly heats up, and the instantaneous temperature can reach above 2500 °C. The PI molecular chains break, and the polyimide material carbonizes to form carbonized spots. The electrode and conductive channel materials of the device change from the polyimide material to the laser-induced graphene material. The physical photo of the processed fabric device array is shown in Figure 2 (a). The environmental scanning electron microscope enlarged view of a single device is shown in Figure 2 (b). It can be observed that the LIG material is embedded in the PI fabric, and there are obvious morphological differences between the carbonized area and the non-carbonized area. At the same time, the width of a single LIG line is about 50 μm, which meets the layout design size, indicating that this process can customize the device morphology and its structure. Moreover, the carbonized LIG material is embedded on the surface of the PI fabric and is seamlessly integrated with the fabric, enabling the stable connection between the LIG material and the PI fabric, as shown in Figure 2 (c). The carbonized LIG material presents a three-dimensional porous structure in the EMES enlarged view, as shown in Figure 2 (d).

[0039] (3) Microscale neck structure of the LIG material: During the design process of a single device, a 25-μm-wide gap region is set in the middle of the conductive channel, as shown by the red dashed box in Figure 3 (a). The LIG material is processed by the laser carbonizing the PI material through a step-by-step laser pulse method to form pulsed carbonized spots. Figure 3 (b) Region A is the continuous laser pulse spots, and region B is the laser pulse spots with a missing part in the middle. When the laser source moves rapidly, the chain of pulsed carbonized spots can form a continuous and dense LIG wire, as shown by the position selected by the blue dashed box in Figure 3 (c). Figure 3 (c) The region selected by the red dashed box is the partial carbonized spot missing due to the design of the gap region (25 μm) in the conductive channel of the device during the direct writing process of the laser pulse. Under the action of the pulsed laser, the instantaneous carbonization of the PI material causes the expansion of the LIG material. In the gap region of the conductive channel, the LIG material is not completely disconnected, forming a point contact structure of the LIG material, thus obtaining the microscale neck structure. That is, during the specific processing process, no special parameter adjustment of the laser is required, and only according to the design layout Figure 1 step direct writing is completed to obtain the microscale neck structure. As shown in Figure 4 (a - b). The surface of the LIG material based on the PI fabric is rough and has large fluctuations, making it difficult to observe the microscale neck structure, as shown in Figure 4 (c). The device using the PI film as the substrate is used to observe and characterize the microscale neck structure. As shown in Figure 4(d) shows the ESEM image of the device based on PI film. It can be observed that the micro - constriction part of the LIG material is slightly looser than other regions due to the absence of carbonized spots of pulsed laser, as Figure 4 (e) shows the enlarged view of the LIG micro - constriction structure.

[0040] The carbon - based device of the present invention based on the micro - constriction structure is embedded on the surface of the polyimide material, and finally the preparation of the carbon - based device array is completed.

[0041] The present invention uses a carbon - based device array to achieve data storage, as Figure 5 shown:

[0042] a) Prepare an array of carbon - based devices on the polyimide material;

[0043] b) Perform a voltage scan on the electrodes of all carbon - based devices in the array, apply a gradually increasing bias voltage. The micro - constriction structure of the carbon - based device breaks to form a nano - gap. At this time, the carbon - based device is in a high - resistance state, forming an initialized memory array. Specifically, it includes:

[0044] When the carbon - based device with a micro - constriction structure is in an unactivated state, the conductive channel is composed of dense LIG material and does not show quantization characteristics. It is in a relatively stable but high - conductance state, and the order of magnitude of its current is usually in the mA order of magnitude. Apply a unidirectional scan voltage to the device, gradually increase the bias voltage. Due to the uneven distribution of the conductive material (looser than other parts) at the micro - constriction structure of the LIG wire, the current density in this area is the largest, and the joule heat accumulation causes the local temperature to rise rapidly until it exceeds the threshold that the carbon - carbon bond can withstand and breaks, resulting in the gradual reduction of the width of the LIG material micro - constriction area and finally forming a nano - gap. This process is called initialization. The device current gradually decreases from the initial mA order of magnitude to the μA order of magnitude and the nA order of magnitude. When the voltage scan continues and the voltage increases to a higher value, the micro - constriction completely breaks, the nano - gap is formed, the device is completely disconnected, and the current drops to the pA, or even fA order of magnitude, indicating the completion of the initialization process.

[0045] In actual operation, the micro - constriction structure of the LIG material can form a nano - gap by applying a unidirectional scan voltage several times. During the application of the first unidirectional scan voltage (0V - 20V), the micro - constriction area undergoes severe burning, accompanied by a visible flame to the naked eye, as Figure 6 (a) shows, which indicates that the local area has experienced strong thermal breakdown. When no operation is performed, the initial current value of the device is in the mA order of magnitude. When the scan voltage rises to 20V, the device is first broken down and the current drops significantly, as Figure 6 (b) shows. However, at this time, the read voltage V READThe current measured at 1 V is still in the μA range, only two orders of magnitude lower than the initial state, indicating that the device has not been completely disconnected and the nano-gap has not been fully formed, as shown in Figure 6 (c). Subsequently, the neck width is significantly reduced, and cracks appear in the narrowest region, which is caused by the ablation of the material due to local thermal breakdown, as shown in Figure 6 (d). To complete the formation of the nano-gap and end the initialization process, a second unidirectional scanning voltage (0 V - 10 V) is applied. When the voltage rises to 2 V, the device breaks down again and the current further decreases, as shown in Figure 6 (e). At this time, the current measured at the reading voltage V READ = 1 V drops to the pA range and oscillates slightly around zero, indicating that the neck has been completely broken and the nano-gap has been successfully formed, marking the completion of the initialization process, as shown in Figure 6 (f). After that, the morphology of the neck changes insignificantly compared with that after the first breakdown, as shown in Figure 6 (g), because the main formation of the nano-gap occurs inside the LIG (micrometer or nanometer scale region), which is difficult to capture by in-situ observation techniques. However, the significant change in current verifies the breakage of the neck and the successful formation of the nano-gap.

[0046] c) After the initialization operation is completed, the state of the device in the memory array switches from the high-resistance state to the low-resistance state. The nano-gap of the conductive channel of the device is closed for the "1" state of data storage; the current state of the device in the memory array is maintained at the low current level, and the nano-gap of the conductive channel of the device is open for the "0" state of data storage. That is, a scanning voltage (hysteresis scan) is applied in the current-limiting state, and the device enters the storage operation state. In this state, the device is initially in a high blocking state (caused by the nano-gap). When a scanning voltage is applied, the strong electric field on both sides of the nano-gap induces electrostatic adsorption of the carbon atom chains, which gradually approach. When the electric field strength reaches the critical value, the carbon atom chains are connected together by forming carbon-carbon covalent bonds, thus establishing a conductive channel and making the device conductive. At this time, the current level rises back to the μA range, completing the write (SET) operation. In the non-volatile low-resistance state, the on-current of the device is maintained in the μA range, and the conductive channel is composed of carbon atom chains on both sides of the nano-gap, indicating that the device officially enters the storage operation state.

[0047] In actual operation, a hysteresis scanning voltage (0 V - 25 V - 0 V) with a current limit of 1 μA is applied to the device, and it is observed that the device conducts instantaneously when the voltage rises to 20 V, as shown in Figure 6 (h). In this state, the current measured at the reading voltage V READ = 1 V returns to the μA range, indicating that a conductive channel has been formed on both sides of the nano-gap, as shown in Figure 6(i) As shown. The generation of the conductive channel is attributed to the action of a high electric field, which prompts the carbon atom chains on both sides of the nano-gap to approach and bond, ultimately forming a conductive path between the nano-gaps. This process is called the SET operation (writing process). After the current quickly reaches the current limiting value, the electric field weakens or disappears. The setting of the current limit restricts the current density, preventing the carbon atom chains from being broken down again due to Joule heat, thus ensuring the stability of the device state.

[0048] It should be noted that during the SET operation, the current limiting value of 1 μA here is mainly used to detect whether the device is operating normally. After the device state stabilizes, in order to meet the requirement of low power consumption, the current limiting value is usually set lower. This is because the current in the fabric device in the high resistance state can usually be maintained at the pA or fA level. Therefore, the current limiting value in the SET operation can be as low as 50 pA. The successful completion of the first SET operation marks the smooth transition of the device from the initialization stage to the storage operation state. Thereafter, through the precise regulation of parameters such as voltage and current, the device can stably perform the writing and erasing operations of the storage state, thus realizing data storage and reading. The storage state of the device and the switching operation between its high and low resistance states will be introduced in detail below.

[0049] The nano-gap of the conductive channel of the device can be closed by two independent methods: electric field control and laser control. Electric field control is adjusted by applying an external voltage; while laser control realizes the closing of the gap by using the thermal expansion effect caused by laser irradiation.

[0050] Finally, through the closing / opening of the gap, the on / off state of the storage device is realized. It should be noted that: the closing of the gap is caused by the bridging of the carbon materials on both sides of the gap by the electric field, similar to the behavior of a nano-electromechanical switch. The carbon materials include but are not limited to carbon atom chains, graphene nanoribbons, carbon nanotubes, amorphous carbon, fullerenes, LIG flakes, etc. These carbon materials connect the gap independently or in combination to allow current to pass through the device; the opening of the gap is due to the disconnection of the carbon materials connected in the gap, making the current unable to pass through the device.

[0051] Testing the storage performance of the storage device of the present invention under an electric field: The present invention uses a CRX-VF probe station from LakeShore and a B1500 semiconductor parameter analyzer from Keysight for electrical testing. First, its I-V characteristic curve is tested. The SET / RESET operations during the storage operation of the device are monitored. The I-V curves of the SET operations in 50 write / erase cycles are as Figure 7(a). When the device enters the storage operation state, the nano-gap has been formed and the device is in the high-resistance state. At this time, by applying a hysteresis scanning voltage (0V - 20V - 0V) with a current limit of 50 pA, as the voltage gradually increases, the current remains almost unchanged at the fA level. When the voltage continues to increase and reaches 10V, the current instantaneously jumps to the current limit value of 50 pA, indicating that the device is successfully turned on. Subsequently, set the reading voltage V READ = 1V, and the current in the low-resistance state of the device is read as I LRS = 10 -4 A, further verifying the on-state of the device, as shown in Figure 7 (b). Figure 7 (c) shows the corresponding I-V curve of the RESET operation during 50 write / erase cycles of the device. During this process, the device is initially in the low-resistance state, and a scanning voltage without current limit (0V - 6V) is applied. As the voltage gradually increases, the current increases linearly. When the voltage reaches 4V, the current rapidly drops from the μA level to the fA level, and the device changes from the low-resistance state to the high-resistance state. Subsequently, set the reading voltage V READ = 1V, and the current in the high-resistance state of the device is read as I LRS = 10 -13 A, indicating that the device is disconnected and the nano-gap is reformed, as shown in Figure 7 (d).

[0052] Storage performance test of the fabric device under laser irradiation: The optoelectronic sensing ability of the fabric device stems from its optical response characteristics, where wavelength and power are two key parameters. The present invention designs the following experiments to focus on studying the effects of laser wavelength and power on the resistance state of the device. Figure 8 (a) shows the schematic diagram of the optical test of the device. The present invention mainly uses continuous lasers with wavelengths of 650 nm (red light), 520 nm (green light), and 450 nm (blue light) as light sources, and the laser power is adjustable from 0 - 450 mW. First, use a laser with a specific wavelength (520 nm) to test the effect of laser power on the performance of the fabric device. The test process is as follows: Set the initial state of the device to the high-resistance state, apply a pulsed laser under the condition of V ds = 1V, the pulse width is 5 seconds, and the pulse interval time is 5 seconds to ensure that the device has enough time to reach thermal equilibrium after each laser irradiation. The laser power starts from 50 mW and gradually increases in steps of 25 mW. At lower laser powers (50 mW to 100 mW), the device hardly responds and the current remains in the high-resistance state; when the laser power increases to 100 mW, the current of the device instantaneously increases from 10 -11 A to 10 -5A shows that laser irradiation with a power of 100 mW can turn on the LIG nanogap. However, when the laser is removed, the device quickly returns to the high-resistance state, indicating that the conductive channel formed at a laser power of 100 mW is unstable. As the laser power continues to increase (from 100 mW to 275 mW), the device current level also increases, indicating that the laser power has an obvious regulating effect on the device current level, as Figure 8 (b) shows. In addition, to study the influence of lasers with different wavelengths on the device performance, this paper selected lasers with wavelengths of 650 nm (red light), 520 nm (green light), and 450 nm (blue light) for experiments. By comparing the changes in the conductive performance of the device under the irradiation of lasers with different wavelengths at the same power (275 mW), it was found that the device showed the same sensitivity to lasers of all wavelengths, indicating that the laser wavelength size has no obvious regulating effect on the device performance, as Figure 8 (c) shows. To explore the ultimate light response speed of the device, the present invention reduced the laser pulse width and found that the shortest light response time of the device is 40 ms, as Figure 8 (d) shows.

[0053] The present invention applied pulsed lasers with powers gradually increasing from 50 mW to 300 mW to the device. The experiment shows that the device current shows a continuous increasing trend until the pulsed laser with a power of 300 mW makes the device quickly change from the high-resistance state to the low-resistance state, and the stable low-resistance state can still be maintained after the laser is removed, realizing the light-assisted storage function, as Figure 8 (e) shows. At this time, if you want to convert the conductive state of the device from the low-resistance state to the high-resistance state, the device needs to be electrically erased (RESET operation). Using the laser pulse operation to replace the SET operation in the electrical storage process, the whole process is abbreviated as "light writing, electrical erasing". As Figure 8 (f) shows, under the irradiation of an independent laser with a power of 300 mW, the device quickly changes from the high-resistance state to the low-resistance state, and the stable low-resistance state can still be maintained after the laser is removed. The current read switch ratio of the device at V READ = 1 V was tested, and the result shows that its switch ratio is 10 8 . Its switch ratio is consistent with the storage performance of the device under voltage control, indicating that the light-assisted storage function and the electrical control storage function are highly compatible, as Figure 8 (f) inset shows.

[0054] Robustness Test of Fabric Devices: To investigate the influence of fabric substrate bending on the electrical characteristics of fabric devices, the fabric PI substrate with fabric devices was adhered to a semi-cylindrical rigid surface with a radius (R) of 0.5 cm, and the strain of a single device was estimated to be about 5%. Then it was placed on a DC probe station (MPI, TS150) and the electrical characteristics during bending were measured using a semiconductor parameter analyzer (Keysight, B1500A), as shown in Figure 9 (a). The test was carried out at room temperature in an atmospheric environment. The bending direction of the fabric substrate was parallel to the direction of the substrate conductive channel, as shown in Figure 9 (b). To further verify the performance stability of the fabric device before and after static bending, the I-V curves of the SET and RESET operations in 100 cycles before and after bending of the device were compared. In the experiment, the red curve represents the performance before bending, and the blue curve represents the performance after bending, as shown in Figure 10 (a) and (b). The results show that before and after bending, the threshold voltage of the fabric device did not change significantly. The SET operation voltage (V SET ) was always stable at 2.5 V, and the RESET operation voltage (V RESET ) remained at 5.5 V. In addition, the I-V curves before and after bending were basically the same, the current values in the high-resistance state and the low-resistance state did not change significantly, and the switching ratio remained at 10 8 , as shown in Figure 10 (c).

[0055] To verify the cycle life of the fabric device under bending conditions, the device was placed on a semi-cylindrical bending surface with a curvature radius of 5 mm for write / erase cycle stability testing. The experimental results show that the device maintained a switching ratio of 108 during 12,000 cycles, as shown in Figure 10 (d), showing high stability and reliability. Even in the bent state, the storage performance of the fabric device was not affected.

[0056] The embodiments described above are not intended to limit the present invention. Any person skilled in the art can make various transformations and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention is defined by the scope of the claims.

Claims

1. A method for fabricating a carbon-based device array on a polyimide material, the steps of which include: 1) Fabricating an array pattern, wherein the devices in the array are distributed in a two-dimensional array, and the planar shape of each device is dumbbell-shaped; All the devices are two-terminal devices, that is, the two ends of the device are electrodes, and the middle slender part connecting the electrodes is a conductive channel. A gap region is provided in the middle of the conductive channel of each device, and the size of the gap region is 25 - 50 μm; 2) Using the polyimide material as a substrate, laying the polyimide material flat on the laser processing platform, and at the same time importing the array pattern of step 1) into the laser control software. The laser scans the polyimide material according to the array pattern by means of a stepwise laser pulse; 3) Under the action of the pulsed laser, the polyimide material is carbonized to form carbonized spots. The materials of the device electrodes and the conductive channels are composed of laser-induced graphene transformed from the polyimide. However, due to the absence of carbonized spots in the gap region in the conductive channel, a microconstriction structure is formed. The carbon-based devices containing the microconstriction structure are embedded in the surface of the polyimide material, and finally the fabrication of the carbon-based device array is completed.

2. The method for preparing a carbon-based device array on a polyimide material according to claim 1, wherein The polyimide material is a PI fabric, a PI plastic or a PI paper.

3. The method for fabricating a carbon-based device array on a polyimide material as claimed in claim 1, wherein The length of the conductive channel of the device is 25 μm - 2000 μm, and the width is 15 μm - 2000 μm.

4. The method for fabricating a carbon-based device array on a polyimide material as claimed in claim 1, wherein The parameters of the laser are: laser power P = 5W - 50W, PPI = 300 - 2000.

5. The method for preparing a carbon-based device array on a polyimide material according to claim 1, characterized in that, Design the array pattern using CAD software and convert it into a format suitable for the laser control software.

6. A method for realizing data storage using a carbon-based device array, the steps of which include the following: 1) Using the method for fabricating a carbon-based device array on a polyimide material as described in claim 1 to fabricate an array of carbon-based devices; 2) Performing single or multiple voltage scans on the electrodes of all the carbon-based devices in the array, and slowly increasing the applied bias voltage. The carbon-based device breaks at the microconstriction structure to form a nano-gap. At this time, the carbon-based device is in a high-resistance state, forming an initialized memory array; 3) Switching the state of the devices in the memory array from the high-resistance state to the low-resistance state, and the nano-gap in the conductive channel of the device is in a closed state, representing the "1" state for data storage; keeping the state of the devices in the memory array as the high-resistance state, and the nano-gap in the conductive channel of the device is in an open state, representing the "0" state for data storage.

7. The method for implementing data storage using a carbon-based device array as claimed in claim 6, wherein The state of the device is adjusted from the high-resistance state to the low-resistance state by scanning the voltage of the device in a current-limiting state.

8. The method for implementing data storage using a carbon-based device array as described in claim 6, characterized in that, The state of the device is adjusted from the high-resistance state to the low-resistance state by applying laser irradiation above the device.

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