A visual neural synapse based on copper / copper oxide nanowires and its preparation method

Abstract

This invention provides a visual neural synapse based on copper / copper oxide nanowires and its preparation method, comprising: (1) treating copper foil to remove the oxide layer on the surface of the copper foil; (2) firing the copper foil obtained in step (1) under air conditions at a firing temperature of 400-450℃ to obtain a copper / copper oxide nanowire film; (3) depositing a silver electrode on the surface of the copper oxide nanowire film in the copper / copper oxide nanowire film, and obtaining a copper / copper oxide nanowire / silver visual neural synapse after the deposition is completed. The visual neural synapse based on copper / copper oxide nanowires can well simulate the basic behavior of visual neural synapses under both light and electrical stimulation.

Description

Technical Field

[0001] This invention belongs to the field of multifunctional memristor fabrication technology, specifically, it relates to a multifunctional visual neural synapse based on copper / copper oxide nanowires and its fabrication method. Background Technology

[0002] With the advent of the big data era, the amount of data that artificial intelligence systems need to process is increasing daily. Currently, the sensors, processors, and memory of computers based on the von Neumann architecture are discrete, linked by a bus. Data needs to travel back and forth between these units multiple times to complete a single data processing step, making the overall system inefficient. Faced with such massive amounts of data in the big data era, intelligence can only meet the data processing demands by increasing the overall processing system area. Therefore, scientists urgently need a new processing system to overcome the shortcomings of the von Neumann computing system.

[0003] The human brain, as the most powerful processing system in nature, possesses parallelism, low power consumption, fault tolerance, self-learning, and robustness that even the world's most powerful supercomputers cannot fully simulate. Simulating the brain's functions could potentially solve the problems of von Neumann computing systems. To simulate brain functions, we must first simulate the brain's most basic unit—the synapse. Memristors, as an emerging device, have a structure similar to brain synapses, and their nonlinear conductance characteristics are remarkably similar to the enhancement and inhibition of brain synapses. Therefore, using memristors to simulate brain synapses has significant advantages.

[0004] Copper oxide is an important semiconductor material with an optical bandgap between 1.2 eV and 1.9 eV and a carrier concentration of 10. 12 -10 18 cm -3 The migration rate is 5-200cm. 2 With a resistivity of 1-30 Ω·cm, copper oxide has been extensively studied in optoelectronic devices and memristors due to its excellent properties.

[0005] Current research on copper oxide-based memristors is limited to simulating basic synaptic functions under electrical stimulation. It lacks research on more complex functions, such as dendritic nerve function and responses to external conditions, thus failing to develop a comprehensive copper oxide memristor integrating perception, storage, and computation. Therefore, it is essential to investigate whether copper oxide memristors can simulate the visual nerve under light stimulation. Summary of the Invention

[0006] To address the problems existing in the prior art, this invention provides a visual neural synapse based on copper / copper oxide nanowires and its preparation method, which can effectively simulate the basic behavior of visual neural synapses under both light and electrical stimulation.

[0007] This invention is achieved through the following technical solution:

[0008] A method for preparing visual neural synapses based on copper / copper oxide nanowires, comprising:

[0009] (1) Treat the copper foil to remove the oxide layer on the surface of the copper foil:

[0010] (2) The copper foil obtained in step (1) is fired in air at a temperature of 400-450°C to obtain a copper / copper oxide nanowire film.

[0011] (3) Silver electrodes were prepared by vapor deposition on the surface of copper oxide nanowire thin film in copper / copper oxide nanowire thin film, and copper / copper oxide nanowire / silver visual nerve synapse was obtained after vapor deposition.

[0012] Preferably, step (1) specifically involves: immersing the copper foil in dilute hydrochloric acid for 10-30 minutes, then removing the copper foil and cleaning it.

[0013] Furthermore, the cleaning process involves rinsing the copper foil first, followed by ultrasonic cleaning for 15–30 minutes at an ultrasonic power of 600–1000W.

[0014] Preferably, the thickness of the copper foil is 0.1 to 2 mm.

[0015] Preferably, in step (2), the temperature is increased from room temperature to 400-450°C at a heating rate of 4-6°C / min during firing.

[0016] Preferably, in step (2), the firing temperature is maintained at 400-450℃ for 240-360 minutes.

[0017] Preferably, in step (3), the vacuum degree used during vapor deposition is 1×10⁻⁶. -4 Pa.

[0018] The visual nerve synapse based on copper / copper oxide nanowires obtained by the aforementioned preparation method comprises, from bottom to top, a copper bottom electrode, a copper oxide nanowire film, and a silver top electrode.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] In this invention, copper atoms on the surface of a copper foil react with oxygen in the air at high temperature to generate copper oxide nanoparticles. Using these copper oxide nanoparticles as growth sites, copper oxide nanowires gradually grow over time, ultimately yielding a copper / copper oxide nanowire film. The fabrication process is simple, rapid, safe, and low-cost, producing high-quality copper oxide nanowire films. Visual nerve synapses made from copper / copper oxide nanowires were successfully fabricated using the obtained copper oxide nanowire films.

[0021] This invention relates to a visual neural synapse using copper / copper oxide nanowires. The shallow and deep traps in the copper oxide nanowire film generate a photogating effect on photogenerated electrons, enabling the device to effectively simulate the functions of visual and ordinary synapses. Under light stimulation, it successfully simulates the basic functions of visual neural synapses, such as short-term memory (STM), long-term memory (LTM), double-pulse dissimilarity (PPF), and peak temporal plasticity (STDP). By utilizing the different light responses at different wavelengths, it simulates the functions of dendritic nerves under light stimulation, successfully simulating logical AND and OR operations. Under light stimulation, it achieves the biologically famous Pavlovian conditioned reflex, and under electrical stimulation, it similarly simulates the functions of brain synapses and dendritic nerves. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the copper / copper oxide nanowire / silver visual nerve synapse structure of the present invention.

[0023] Figure 2 This is a SEM image of the copper oxide nanowire thin film in Example 2 of the present invention.

[0024] Figure 3 This is a schematic diagram of the connection between two copper / copper oxide nanowires / silver visual nerve synapses in Embodiment 3 of the present invention.

[0025] Figure 4 This is a graph showing the IV curve data of the copper / copper oxide nanowire / silver visual nerve synapse in Example 2 of the present invention.

[0026] Figure 5 This is a diagram of the dual-pulse dissimilarity data of copper / copper oxide nanowires / silver visual nerve synapses in Example 2 of the present invention.

[0027] Figure 6 This is a STDP data diagram of the copper / copper oxide nanowire / silver visual nerve synapse in Example 2 of the present invention.

[0028] Figure 7 This is a graph showing the continuous enhancement and inhibition data of copper / copper oxide nanowires / silver visual nerve synapses in Example 2 of the present invention.

[0029] Figure 8This is a graph showing the test data of the dendritic structure of the copper / copper oxide nanowire / silver visual nerve synapse under electrical stimulation of the copper / copper oxide nanowire / silver visual nerve synapse in Example 3 of the present invention.

[0030] Figure 9 This is a data graph of the Pavlovian conditioned reflex of the copper / copper oxide nanowire / silver visual nerve synapse under electrical stimulation of the copper / copper oxide nanowire / silver visual nerve synapse in Example 2 of the present invention.

[0031] Figure 10 This is a graph showing the double-pulse dissimilarity data of the copper / copper oxide nanowire / silver visual nerve synapse under photostimulation in Example 2 of the present invention.

[0032] Figure 11 This is a Pavlovian conditioned reflex data diagram of the copper / copper oxide nanowire / silver visual nerve synapse under light stimulation during electrical stimulation of the copper / copper oxide nanowire / silver visual nerve synapse in Example 2 of the present invention. Detailed Implementation

[0033] To further understand the present invention, the present invention will be described below with reference to embodiments. These descriptions are only for further explaining the features and advantages of the present invention and are not intended to limit the claims of the present invention.

[0034] This invention discloses a method for preparing a photoelectrically stimulated multifunctional visual nerve synapse based on copper / copper oxide nanowires, comprising the following steps:

[0035] (1) Treat and clean the surface of the copper foil to remove the oxide layer:

[0036] (2) Preparation of copper / copper oxide nanowire thin film: The copper foil obtained in step (1) is placed in a muffle furnace and fired in air. The firing parameters are: the heating rate is 4-6℃ / min from room temperature to 400-450℃, and the temperature is held for 240-360min before naturally cooling to room temperature. During this process, the copper atoms on the surface of the copper foil react with oxygen in the air at high temperature to generate copper oxide nanoparticles. Using these copper oxide nanoparticles as growth sites, they gradually grow into copper oxide nanowires as time increases, and finally copper / copper oxide nanowire thin film is obtained.

[0037] (3) Preparation of photo-electric stimulation multifunctional visual nerve synapse of copper / copper oxide / silver: On the surface of the copper / copper oxide nanowire thin film prepared in step (2), a silver electrode is prepared in a vacuum environment by vapor deposition. After vapor deposition, copper / copper oxide nanowire / silver visual nerve synapse is obtained.

[0038] Step (1) specifically involves: cutting the purchased copper foil with a thickness of 0.1–2 mm into small pieces, sanding the surface of the copper foil with sandpaper, and then immersing it in dilute hydrochloric acid for 10–30 minutes to remove the oxide layer on the surface of the copper foil. After treatment, the copper foil is removed and repeatedly rinsed with deionized water to remove the hydrochloric acid. Then, the copper foil is ultrasonically cleaned in acetone, ethanol, and deionized water for 15–30 minutes at an ultrasonic power of 600–1000 W. The preferred thickness of the flexible substrate copper foil is 0.1–0.2 mm, and the preferred thickness of the rigid substrate copper foil is 2 mm.

[0039] In step (2), the preferred heating rate is 5℃ / min, the holding temperature is 400℃, and the holding time is 240min.

[0040] The photoelectric stimulation multifunctional visual nerve synapse prepared by the copper / copper oxide nanowires of the present invention mainly consists of a copper bottom electrode, a copper oxide nanowire thin film, and a silver top electrode.

[0041] Example 1: Preparation of copper / copper oxide nanowires / silver photo-electro-stimulated multifunctional visual nerve synapses.

[0042] The preparation process is as follows:

[0043] (1) Cutting, processing and cleaning of copper foil: Cut the purchased 0.1mm thick copper foil into squares of 1×1cm. Polish the surface of the copper foil with 2000-grit sandpaper. After polishing, immerse it in 1mol / L dilute hydrochloric acid for 10 minutes to remove the oxide layer on the surface of the copper foil. After processing, remove the copper foil and rinse it repeatedly with deionized water to remove the hydrochloric acid. Then, ultrasonically clean the copper foil in acetone, ethanol and deionized water for 15 minutes with an ultrasonic power of 600W.

[0044] (2) Preparation of copper / copper oxide nanowire thin film: The copper foil obtained in step (1) was placed in a muffle furnace and fired in air. The firing parameters were: the heating rate was 6℃ / min from room temperature to 450℃, and the temperature was held for 360min before naturally cooling to room temperature to obtain copper / copper oxide nanowire thin film.

[0045] (3) Preparation of copper / copper oxide nanowires / silver photo-electrostimulation multifunctional visual nerve synapses: On the copper / copper oxide nanowire film prepared in step (2), a 1×10 -4 Silver electrodes were prepared under vacuum at a rate of 0.4 nm / s using a 1 mm diameter circular mask. After evaporation, a copper / copper oxide nanowire / silver photo-electro-stimulatory multifunctional visual nerve synapse was obtained.

[0046] Example 2: Preparation of Copper / Copper Oxide Nanowires / Silver Photo-Electro-Stimulation Multifunctional Visual Neuron Synapses

[0047] The production process is as follows:

[0048] (1) Cutting, processing and cleaning of copper foil: Cut the purchased 0.2mm thick copper foil into squares of 1×1cm. Use 2000-grit sandpaper to polish the surface of the copper foil. After polishing, immerse it in 1mol / L dilute hydrochloric acid for 30 minutes to remove the oxide layer on the surface of the copper foil. After treatment, take out the copper foil and rinse it repeatedly with deionized water to remove the hydrochloric acid. Then, ultrasonically clean the copper foil in acetone, ethanol and deionized water for 30 minutes with an ultrasonic power of 1000W.

[0049] (2) Preparation of copper / copper oxide nanowire thin film: The copper foil obtained in step (1) was placed in a muffle furnace and fired in air. The firing parameters were: the heating rate was 4℃ / min from room temperature to 400℃, and the temperature was held for 240min before naturally cooling to room temperature to obtain copper / copper oxide nanowire thin film.

[0050] (3) Fabrication of a multifunctional visual nerve synapse device using copper / copper oxide nanowires / silver photo-electro-stimulation: On the copper / copper oxide nanowire film prepared in step (2), a 1×10 -4 Silver electrodes were prepared under vacuum at a rate of 0.4 nm / s using a 1 mm diameter circular mask. After evaporation, copper / copper oxide nanowires / silver visual nerve synapses were obtained.

[0051] Example 3: Preparation of Copper / Copper Oxide Nanowires / Silver Photo-Electro-Stimulation Multifunctional Visual Neuronal Synapses

[0052] The production process is as follows:

[0053] (1) Cutting, processing and cleaning of copper foil: Cut the purchased 0.2mm thick copper foil into squares of 1×1cm. Use 2000-grit sandpaper to polish the surface of the copper foil. After polishing, immerse it in 1mol / L dilute hydrochloric acid for 30 minutes to remove the oxide layer on the surface of the copper foil. After treatment, take out the copper foil and rinse it repeatedly with deionized water to remove the hydrochloric acid. Then, ultrasonically clean the copper foil in acetone, ethanol and deionized water for 30 minutes with an ultrasonic power of 1000W.

[0054] (2) Preparation of copper / copper oxide nanowire thin film: The copper foil obtained in step (1) was placed in a muffle furnace and fired in air. The firing parameters were: the heating rate was 4℃ / min from room temperature to 400℃, and the temperature was held for 240min before naturally cooling to room temperature to obtain copper / copper oxide nanowire thin film.

[0055] (3) Preparation of copper / copper oxide nanowires / silver photo-electrostimulation multifunctional visual nerve synapses: On the copper / copper oxide nanowire film prepared in step (2), a 1×10-4 Silver electrodes were prepared under vacuum at a rate of 0.4 nm / s. A circular mask with a diameter of 1 mm was used as the evaporation mask. After evaporation, a copper / copper oxide nanowire / silver photo-electro-stimulatory multifunctional visual nerve synapse was obtained.

[0056] (4) Preparation and assembly of a copper / copper oxide nanowire / silver photo-electric stimulation multifunctional visual nerve synapse device that can simulate dendritic function: Connect the bottom copper electrodes of the two copper / copper oxide nanowire / silver photo-electric stimulation multifunctional visual nerve synapses prepared in step (3) together to form a device with an input at both ends and an output at one end, and obtain a copper / copper oxide nanowire / silver photo-electric stimulation multifunctional visual nerve synapse device that can simulate dendritic function.

[0057] Example 4: Preparation of Copper / Copper Oxide Nanowires / Silver Photo-Electro-Stimulation Multifunctional Flexible Visual Neural Synapses

[0058] The production process is as follows:

[0059] (1) Cutting, processing and cleaning of copper foil: Cut the purchased flexible copper foil with a thickness of 0.1 mm into squares of 1×1 cm. Use 2000-grit sandpaper to polish the surface of the copper foil. After polishing, immerse it in 1 mol / L dilute hydrochloric acid for 30 min to remove the oxide layer on the surface of the copper foil. After the treatment, take out the copper foil and rinse it repeatedly with deionized water to remove the hydrochloric acid. Then, ultrasonically clean the copper foil in acetone, ethanol and deionized water for 30 min with an ultrasonic power of 1000W.

[0060] (2) Preparation of copper / copper oxide nanowire thin film: The copper foil obtained in step (1) was placed in a muffle furnace and fired in air. The firing parameters were: the heating rate was 4℃ / min from room temperature to 400℃, and the temperature was held for 240min before naturally cooling to room temperature to obtain copper / copper oxide nanowire thin film.

[0061] (3) Fabrication of flexible copper / copper oxide nanowires / silver photo-electrostimulation multifunctional flexible visual nerve synapses: On the copper / copper oxide nanowire film prepared in step (2), a 1×10 -4 Silver electrodes were prepared under vacuum at a rate of 0.4 nm / s using a 1 mm diameter circular mask. After evaporation, a copper / copper oxide nanowire / silver photo-electro-stimulatory multifunctional flexible visual nerve synapse was obtained.

[0062] Figure 1 This is a schematic diagram of the copper / copper oxide nanowire / silver photo-electric stimulation multifunctional visual nerve synapse structure of the present invention, which includes, from bottom to top, a copper bottom electrode, a copper oxide nanowire film, and a silver top electrode.

[0063] Figure 2This is a SEM image of the copper oxide nanowire thin film in Example 2 of the present invention. It can be clearly seen from the image that the uniformly arranged copper oxide nanowires constitute a dense copper oxide nanowire thin film, and the nanowires are oriented in a consistent manner.

[0064] Figure 3 This is a schematic diagram of the connection between two copper / copper oxide nanowires / silver visual nerve synapses in Embodiment 3 of the present invention. By connecting the bottom copper electrodes of the two memristors together, a structure with input at both ends and output at one end is formed to simulate the function of dendritic nerves in the brain.

[0065] Figure 4 The image shows the IV curve data of the copper / copper oxide nanowire / silver visual nerve synapse in Example 2 of this invention. The obtained curve conforms to the traditional non-volatile memristor curve and has obvious high-resistivity and low-resistivity states.

[0066] Figure 5 The image shows the dual-pulse heterogeneity data of the copper / copper oxide nanowire / silver visual nerve synapse in Embodiment 2 of the present invention. When two consecutive pulses are applied between them, the conductivity of the device shows a continuous increase, and the postsynaptic current generated by the second pulse is higher than that generated by the first pulse.

[0067] Figure 6 The image shows STDP data of the copper / copper oxide nanowire / silver visual nerve synapse in Embodiment 2 of the present invention. Applying a pulse to the top electrode is a presynaptic stimulus, and applying a pulse to the bottom electrode is a postsynaptic stimulus. By using devices with different application intervals between the two, the important peak time-permissive plasticity function of biological synapses can be simulated.

[0068] Figure 7 The diagram shows the continuous enhancement and inhibition data of the copper / copper oxide nanowire / silver visual nerve synapse in Example 2 of this invention. The continuous positive pulse applied to the device significantly increases the device's conductivity, and the conductivity decreases rapidly after a negative pulse is applied to the device.

[0069] Figure 8 This is a test data diagram of the dendritic structure of the copper / copper oxide nanowire / silver visual nerve synapse under electrical stimulation of copper / copper oxide nanowire / silver visual nerve synapse in Embodiment 3 of the present invention. By using the structure with input at two ends and output at one end, logical "AND" and logical "OR" operations can be realized by adjusting the reading voltage at the output end.

[0070] Figure 9 This is a Pavlovian conditioned reflex data diagram of the copper / copper oxide nanowire / silver visual nerve synapse under electrical stimulation of the copper / copper oxide nanowire / silver visual nerve synapse in Embodiment 2 of the present invention. Low voltage is used as the ringing condition and high voltage is used as the food condition. Through training, the device can reach the specified current threshold under low voltage conditions.

[0071] Figure 10 The image shows the dual-pulse dissimilarity data of the copper / copper oxide nanowire / silver visual nerve synapse under photostimulation in Embodiment 2 of the present invention. When two consecutive light pulses are applied between them, the conductivity of the device shows a continuous enhancement, and the postsynaptic current generated by the second light pulse is higher than that generated by the first light pulse.

[0072] Figure 11 This is a Pavlovian conditioned reflex data diagram of the copper / copper oxide nanowire / silver visual nerve synapse under photostimulation during electrical stimulation of the copper / copper oxide nanowire / silver visual nerve synapse in Embodiment 2 of the present invention. Utilizing the different responses of the device to light in different wavelength bands, a low-response 405nm light pulse is used as the ringing condition, and a high-response 365nm light pulse is used as the food condition. Through training, the device can reach the specified current threshold under the low-response 405nm light pulse condition.

[0073] As can be seen from the above embodiments, the copper / copper oxide nanowire / silver visual synapse prepared by this invention has a simple structure, is easy to prepare, and is low in cost and simple in process. Most importantly, it can well simulate the basic functions of biological visual synapses and the information logic processing capabilities between multiple neurons. Therefore, it can be applied to the field of artificial intelligence, as well as to artificial neural networks, and has broad application prospects.

Claims

1. A method for preparing visual neural synapses based on copper / copper oxide nanowires, characterized in that, include: (1) Treat the copper foil to remove the oxide layer on the surface of the copper foil: (2) The copper foil obtained in step (1) is fired in air at a temperature of 400~450 ℃ to obtain a copper / copper oxide nanowire film; the temperature is increased from room temperature to 400~450 ℃ at a rate of 4~6 ℃ / min during firing. (3) Silver electrodes were prepared by vapor deposition on the surface of copper oxide nanowire thin film in copper / copper oxide nanowire thin film. After vapor deposition, copper / copper oxide nanowire / silver visual nerve synapse was obtained.

2. The method for preparing visual neural synapses based on copper / copper oxide nanowires according to claim 1, characterized in that, Step (1) specifically involves: immersing the copper foil in dilute hydrochloric acid for 10-30 minutes, then removing and cleaning the copper foil.

3. The method for preparing visual neural synapses based on copper / copper oxide nanowires according to claim 2, characterized in that, The cleaning process involves rinsing the copper foil first, followed by ultrasonic cleaning for 15-30 minutes at an ultrasonic power of 600-1000W.

4. The method for preparing visual neural synapses based on copper / copper oxide nanowires according to claim 1, characterized in that, The thickness of the copper foil is 0.1~2 mm.

5. The method for preparing visual neural synapses based on copper / copper oxide nanowires according to claim 1, characterized in that, In step (2), the firing temperature is maintained at 400~450 ℃ for 240~360 min.

6. The method for preparing visual neural synapses based on copper / copper oxide nanowires according to claim 1, characterized in that, In step (3), the vacuum degree used during vapor deposition is 1×10⁻⁶. -4 Pa.

7. A visual neural synapse based on copper / copper oxide nanowires obtained by the preparation method according to any one of claims 1-6, characterized in that, From bottom to top, it includes a copper bottom electrode, a copper oxide nanowire thin film, and a silver top electrode.

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