Variable retention time organic electrochemical transistor based on gate capacitance and application of variable retention time organic electrochemical transistor in synapse simulation

Abstract

The invention discloses a variable retention time organic electrochemical transistor based on gate capacitance and application of the variable retention time organic electrochemical transistor in synapse simulation. The invention provides a method for simulating neuron behaviors based on an organic electrochemical transistor, which comprises the following steps of: taking a grid electrode of the organic electrochemical transistor as a presynaptic membrane, taking a channel as a postsynaptic membrane, and doping and de-doping ions in an electrolyte solution to the channel under the driving of double-pulse voltage of the grid electrode so as to simulate a neurotransmitter to realize information conduction; according to the method, the short-time synaptic plasticity is regulated and controlled by adjusting the size of the grid capacitance. The invention also provides a neuromorphic organic electrochemical transistor and a neuromorphic device for realizing the method. The neuromorphic organic electrochemical transistor provided by the invention has the characteristics of controllable plastic function and adjustable retention time, so that a foundation is laid for establishing a chemical response plastic device, and possibility is provided for realizing complex synaptic plastic function simulation by using the organic electrochemical transistor structure.

Description

Technical Field

[0001] The present invention belongs to the field of neuromorphic devices and functions, and particularly relates to an organic electrochemical transistor for regulating the retention time of synaptic-like functions by adjusting the gate capacitance of the organic electrochemical transistor and its application in synaptic-like devices. Background Art

[0002] An organic electrochemical transistor (OECT) is a novel transistor technology for hybrid ion-electron transport. Different from traditional organic field-effect transistor (OFET) devices, OECT uses an electrolyte containing migratable ions to replace the dielectric layer in OFET devices, and uses a polymer semiconductor material that can simultaneously transport ions and carriers as the channel layer, and adjusts the redox state and conductivity of the channel layer material by driving ions into the channel layer.

[0003] Due to the characteristics of high transconductance, low operating voltage, fast response speed, high sensitivity, and compatibility with the biological environment of the organic electrochemical transistor, it can simulate the behavior of neurons and has important potential in brain-computer interfaces, brain-like computing, and neural prosthetics. During the simulation process, the gate of the organic electrochemical transistor acts as the presynaptic membrane, the channel acts as the postsynaptic membrane, and the ion flow in the electrolyte solution can mimic neurotransmitters, thus realizing information conduction.

[0004] The synaptic plasticity of neurons is generally considered to be the molecular biological mechanism of brain learning and memory. It refers to the change phenomenon of the enhancement or weakening of synaptic transmission efficiency, which is an important feature of the nervous system and an important guarantee for the nervous system to realize its functions. According to the duration, synaptic plasticity can be divided into short-term synaptic plasticity and long-term synaptic plasticity. Short-term synaptic plasticity includes two types: short-term potentiation and short-term depression. Different from long-term synaptic plasticity, the generation of short-term synaptic plasticity mainly depends on the change of neurotransmitter release probability, which often determines the information processing and response mode of neural circuits, not only directly participates in the recognition and processing of input signals, but also has an important impact on the expression of long-term synaptic plasticity. Therefore, the development of organic electrochemical transistor devices with adjustable synaptic plasticity function strength is of great significance for designing efficient and multifunctional brain-like computing circuits and constructing intelligent brain-computer interaction devices.

[0005] However, the current research on the neuromorphic functions of organic electrochemical transistors mainly focuses on the design and modification of channel materials, and less research has been done on the gate, which is an important part of it.

[0006] In view of this, the present invention is hereby provided. Summary of the Invention

[0007] The object of the present invention is to provide an organic electrochemical transistor with a novel structure and its application in mimicking synapses. The organic electrochemical transistor has the characteristics of controllable plasticity function and adjustable retention time, thereby laying a foundation for establishing a chemically responsive plasticity device and providing the possibility of simulating complex synaptic plasticity functions using the structure of the organic electrochemical transistor.

[0008] To achieve the above object, the present invention adopts the following technical solutions: In a first aspect, the present invention provides a method for simulating neuron behavior based on an organic electrochemical transistor, including: using the gate of the organic electrochemical transistor as the presynaptic membrane and the channel as the postsynaptic membrane. Under the drive of the gate voltage, ions in the electrolyte solution are doped and de-doped into the channel to simulate neurotransmitters and achieve information conduction; wherein, the method realizes the regulation of short-term synaptic plasticity by adjusting the size of the gate capacitance.

[0009] In the present invention, the short-term synaptic plasticity is characterized by the retention time; the retention time is the interval time required for the first pulse to have no effect on the second pulse when a double-pulse voltage is applied to the gate; the size of the gate capacitance is positively correlated with the length of the retention time. Specifically, the larger the gate capacitance, the larger the difference in pulse currents between the two pulses and the longer the retention time.

[0010] The calculation method of the retention time is as follows: First, the double-exponential function formula that can fit the decay curve of the conductance difference is used to calculate the time constants τ1 and τ2 related to the distribution of ions between the gate and the channel, and then the formula is used to calculate the retention time τ, where A1 and A2 are the weights of the kinetic processes of ions at the gate and the channel, and ΔG0 is the offset value of the initial conductance.

[0011] The regulation mechanism is as follows: In the ion circuit of the neuromorphic transistor, the voltage drop of the gate voltage affects the electric field differently, so that the migration and aggregation of ions in the solution to the channel and the doping with the organic polymer semiconductor material are different, thereby regulating the channel current; when a double-pulse voltage is applied, the capacitance of the gate not only affects the voltage drop, but its ion adsorption ability causes a lag effect on the movement of ions, thereby realizing the regulation of neuromorphic function plasticity.

[0012] In the above method, the adjustable range of the gate capacitance of the neuromorphic transistor is 1.12 μF - 1.35 mF.

[0013] According to an embodiment of the present invention, the gate capacitance is obtained by measuring the electrochemical impedance spectrum of a three-electrode system through a workstation for different working electrodes in a phosphate buffer solution. The three-electrode system uses different glassy carbon electrodes as the working electrode, an Ag / AgCl electrode as the reference electrode, and a Pt wire as the counter electrode.

[0014] In the above method, the gate is selected from one or more of an Ag / AgCl electrode, a bare glassy carbon electrode, a glassy carbon electrode modified with carbon nanotubes, and a glassy carbon electrode modified with a modified organic polymer semiconductor material PEDOT:PSS.

[0015] According to an embodiment of the present invention, the glassy carbon electrode modified with carbon nanotubes is obtained by the following method: After mixing a carbon nanotube dispersion with isopropanol and a Nafion solution, 2.5 - 5 μL is taken and drop-coated onto a polished glassy carbon electrode, and then dried to obtain the glassy carbon electrode modified with carbon nanotubes.

[0016] According to an embodiment of the present invention, the glassy carbon electrode modified with the modified organic polymer semiconductor material PEDOT:PSS is obtained by the following method: 40 - 50 mg of ethylene glycol (EG) that can increase the film conductivity, 0.5 - 1 mg of dodecylbenzenesulfonic acid (DBSA) that acts as a surfactant, 5 - 10 mg of 3-glycidoxypropyltrimethoxysilane (GOPTS) that can increase the viscosity, and 1 - 2 ml of a PEDOT:PSS solution are mixed and ultrasonically mixed for 20 - 30 min to prepare a modified organic polymer semiconductor material PEDOT:PSS solution. 2.5 - 5 μL of the mixed solution is taken from it and drop-coated onto a polished bare glassy carbon electrode, and then placed in a tube furnace and subjected to high-temperature treatment at 120 - 160 °C for 20 - 30 min in a nitrogen atmosphere, and then the temperature is decreased step by step to obtain the glassy carbon electrode modified with the modified organic polymer semiconductor material PEDOT:PSS.

[0017] In a second aspect, the present invention provides a neuromorphic organic electrochemical transistor, including: a substrate, a gate, an electrolyte solution, a channel, a source electrode, and a drain electrode; the gate is a capacitance-adjustable gate capable of regulating the retention time of short-term synaptic plasticity through the above-mentioned regulation method.

[0018] In the above neuromorphic organic electrochemical transistor, the gate is selected from one or more of an Ag / AgCl electrode, a bare glassy carbon electrode, a glassy carbon electrode modified with carbon nanotubes, and a glassy carbon electrode modified with a modified organic polymer semiconductor material PEDOT:PSS. Preferably, the gate is a glassy carbon electrode modified with carbon nanotubes and a glassy carbon electrode modified with a modified organic polymer semiconductor material PEDOT:PSS. Using such electrodes as the gate for modification, an intelligent synaptic-like device for chemical substance recognition and response can be further prepared.

[0019] In the above-mentioned neuromorphic organic electrochemical transistor, both ends of the channel are respectively connected to the source electrode and the drain electrode; wherein the material of the channel is alumina ceramic, and its size is length: 10~100 μm × width: 0.1~1 cm; both the source electrode and the drain electrode are gold electrodes, and their thickness is 1~10 μm; the surface of the interdigital electrode is modified with a semiconductor thin film; the semiconductor thin film is formed by a mixed solution of a modified organic semiconductor polymer; the substrate is alumina ceramic.

[0020] The mixed solution of the modified organic semiconductor polymer is obtained by the following method: Mix 40~50 mg of ethylene glycol (EG) that can increase the conductivity of the thin film, 0.5~1 mg of dodecylbenzenesulfonic acid (DBSA) that acts as a surfactant, 5~10 mg of 3-glycidoxypropyltrimethoxysilane (GOPTS) that can increase the viscosity, and 1~2 ml of PEDOT:PSS solution, and perform ultrasonic treatment for 20~30 min to mix evenly to obtain a modified organic polymer semiconductor material PEDOT:PSS solution.

[0021] In a third aspect, the present invention also provides a neuromorphic device containing the above-mentioned neuromorphic organic electrochemical transistor.

[0022] Furthermore, the neuromorphic device is a neuromorphic synapse-like device.

[0023] In a fourth aspect, the present invention also provides a test method for the short-term plasticity retention time of a neuromorphic transistor. The neuromorphic transistor includes a gate electrode, a source electrode, a drain electrode, and a channel; the test method includes: using the gate electrode as the working electrode, using the source electrode, the drain electrode, and the channel as interdigital electrodes, placing the working electrode and the interdigital electrodes in an electrolyte solution, applying a double-pulse voltage to the gate electrode to imitate the double-pulse behavior of synaptic plasticity, and fitting the retention time.

[0024] In the above test method, the gate electrode is selected from one or more of an Ag / AgCl electrode, a bare glassy carbon electrode, a glassy carbon electrode modified with carbon nanotubes, and a glassy carbon electrode modified with a modified organic polymer semiconductor material PEDOT:PSS.

[0025] In the above test method, the operating parameters of the double-pulse voltage are: the duration of a single pulse is 10~100 ms, the magnitude of the pulse voltage value is 0.1~0.5 V, the interval time between two pulses varies between 20 ms and 1000 ms, the source electrode is grounded, and a constant voltage of -0.1~0.5 V is applied to the drain electrode.

[0026] Compared with the prior art, the beneficial effects achieved by the present invention are: The present invention firstly proposes that the length of the short-term synaptic plasticity retention time is positively correlated with the gate capacitance of the neuromorphic transistor. The larger the gate capacitance, the longer the short-term synaptic plasticity retention time. Utilizing this discovery, the present invention proposes a neuromorphic organic electrochemical transistor with a novel structure, which has the characteristics of controllable plasticity function and adjustable retention time, thus laying a foundation for establishing a chemically responsive plasticity device and providing the possibility for simulating complex synaptic plasticity functions using the organic electrochemical transistor structure. At the same time, the present invention also provides a method for testing the short-term plasticity retention time of a neuromorphic transistor, and this method is simple and efficient. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is the equivalent circuit of the ion circuit of the synaptic-mimicking organic electrochemical transistor provided by the present invention.

[0028] Figure 2 It is the test diagram of the short-term synaptic plasticity performance of the organic electrochemical transistor with an Ag / AgCl electrode as the gate in the embodiment of the present invention; among them, (A) is the double-pulse inhibition test diagram, and (B) is the curve diagram of the conductance difference between two pulses varying with the time interval between two pulses.

[0029] Figure 3 It is the comparison diagram of the retention time calculated by fitting the conductance difference varying with the time interval between two pulses with a double-exponential function when double-pulse inhibition is performed with different gates in the embodiment of the present invention.

[0030] Figure 4 It is the Nyquist diagram obtained by testing the capacitance of the electrochemical impedance spectrum at different gates and the channel in the embodiment of the present invention; among them, (A) is the bare glassy carbon electrode, (B) is the glassy carbon electrode modified with carbon nanotubes, (C) is the glassy carbon electrode modified with the modified organic polymer semiconductor material PEDOT:PSS, and (D) is the interdigitated electrode modified with the modified organic polymer semiconductor material PEDOT:PSS.

[0031] Figure 5 It is the schematic diagram of the voltage drop in the ion circuit of the neuromorphic device with different gates in the embodiment of the present invention; among them, (A) is the polarized electrode and (B) is the non-polarized electrode.

[0032] Figure 6 It is the change diagram of the gate current and the channel current when the neuromorphic device with an Ag / AgCl electrode as the gate in the embodiment of the present invention is turned on and off at the transient time scale.

[0033] Figure 7 It is the comparison diagram of the transient time constants at the gate and the channel when the glassy carbon electrode modified with carbon nanotubes and the glassy carbon electrode modified with the modified organic polymer semiconductor material PEDOT:PSS are turned on and off in the embodiment of the present invention.

[0034] Figure 8 This is a schematic diagram of the doping and de-doping of double-pulse process ions at the channel and the adsorption and desorption processes of the gate in the embodiments of the present invention. Detailed implementation manners

[0035] The present invention will be further described below in conjunction with specific embodiments, but the present invention is not limited to the following embodiments.

[0036] Unless otherwise specified, the experimental methods used in the following embodiments are all conventional methods.

[0037] Unless otherwise specified, the materials, reagents, etc. used in the following embodiments can all be obtained through commercial channels.

[0038] The reagents used in the following embodiments are as follows: Phosphate buffer solution, PBS solution; organic polymer semiconductor solution, PEDOT:PSS solution; crosslinking agent, 3-glycidoxypropyltrimethoxysilane (GOPTS); solvent for increasing the film conductivity, ethylene glycol (EG); surfactant, dodecylbenzenesulfonic acid (DBSA); isopropanol was purchased from SIGMA-ALDRICH.

[0039] Carbon nanotube dispersion was purchased from Xianfeng Nanomaterials Technology Co., Ltd.

[0040] Interdigitated electrodes were purchased from Guangzhou Yuxin Technology Sensing Co., Ltd.

[0041] Embodiment 1 This embodiment provides a synaptic-like organic electrochemical transistor, and its structure includes: a substrate, a gate, an electrolyte solution, a channel, a source electrode, and a drain electrode; The gate is composed of an Ag / AgCl electrode, a bare glassy carbon electrode, a glassy carbon electrode modified with carbon nanotubes, and a glassy carbon electrode modified with a modified organic polymer semiconductor material PEDOT:PSS; Both ends of the channel are respectively connected to the source electrode and the drain electrode to form interdigitated electrodes; the size of the channel is: length: 100 μm × width: 1 cm; both the source electrode and the drain electrode are gold electrodes, and their thickness is 7 μm; The electrolyte solution is phosphate buffered saline; The substrate is alumina ceramic; The equivalent circuit of the ion circuit of the above-mentioned organic electrochemical transistor includes: the interface capacitance of the gate - electrolyte solution, the electrolyte solution resistance, and the interface capacitance of the channel - electrolyte solution; the gate voltage drop forms an electric field, which is used to control ion aggregation by the gate, and then adjust the conductance of the channel, thereby mimicking the behavior of a synapse. Due to the large gate capacitance, the gate voltage is mainly at the interface of the channel - electrolyte solution. The resulting large electric field causes cations to aggregate at the channel, resulting in de - doping and a large decrease in current; when the gate voltage is removed, due to the large gate capacitance, only a small part of the anions at the gate return to the channel for doping, so the channel current recovers less; when the second pulse voltage is applied, cations continue to cause a decrease in the channel current, and finally, the difference between the two pulse currents is large; similarly, when the gate capacitance is small, the current difference is small; and as the pulse interval time is lengthened, this relaxation effect caused by the gate capacitance is more significant, so when the gate capacitance is large, the retention time is longer.

[0042] The preparation of the above - mentioned electrode is as follows: Preparation process of the bare glassy carbon electrode: Take a small amount of alumina polishing powder and place it in the electrode plate, drop two drops of deionized water, place the glassy carbon electrode on it and polish it in a figure - eight shape. During polishing, it is required to be slow and smooth. After polishing for 2 - 3 minutes, rinse off the surface polishing powder with deionized water and clean it in an ultrasonic cleaner to obtain the bare glassy carbon electrode.

[0043] Preparation process of the glassy carbon electrode modified with carbon nanotubes: Mix 375 μL of 1 mg / mL carbon nanotube dispersion, 125 μL of isopropanol, and 30 μL of 5% Nafion solution, ultrasonically mix for 5 minutes, then take 2.5 μL of the mixed solution and drop - coat it onto the polished bare glassy carbon electrode, and dry it under a baking lamp to obtain the glassy carbon electrode modified with carbon nanotubes.

[0044] Preparation process of the glassy carbon electrode modified with the modified organic polymer semiconductor material PEDOT:PSS: Mix 50 mg of ethylene glycol (EG) that can increase the film conductivity, 1 mg of dodecylbenzenesulfonic acid (DBSA) that acts as a surfactant, 10 mg of 3 - glycidoxypropyltrimethoxysilane (GOPTS) that can increase the viscosity, and 1 mL of PEDOT:PSS solution, and ultrasonically mix for 30 min to obtain the modified organic polymer semiconductor material PEDOT:PSS solution. Take 2.5 μL of the mixed solution and drop - coat it onto the polished bare glassy carbon electrode, then place it in a tube furnace and perform high - temperature treatment at 120 °C for 20 min in a nitrogen atmosphere, and then cool down step - by - step to obtain the glassy carbon electrode modified with the modified organic polymer semiconductor material PEDOT:PSS.

[0045] The preparation of the above - mentioned synaptic - mimicking organic electrochemical transistor is as follows: S100: Prepare a modified organic semiconductor polymer mixed solution In this step, other reagents need to be added to the organic semiconductor polymer (such as PEDOT:PSS) solution used in the experiment before it can be used for electrode modification. This is mainly because adding other reagents can improve the performance of the semiconductor thin film, facilitate semiconductor film formation, and enhance the detection performance of the organic electrochemical transistor.

[0046] The specific operation is as follows: Mix 50 mg of ethylene glycol (EG) that can increase the conductivity of the film, 1 mg of dodecylbenzenesulfonic acid (DBSA) that acts as a surfactant, 10 mg of 3-glycidoxypropyltrimethoxysilane (GOPTS) that can increase the viscosity, and 1 ml of PEDOT:PSS solution, and perform ultrasonic mixing for 30 min to obtain a modified organic polymer semiconductor material PEDOT:PSS solution.

[0047] S200: Perform spin coating modification of the interdigitated electrode In this step, take 2.5 μL of the modified organic semiconductor polymer mixed solution and drop it onto the interdigitated electrode, and use the spin coating method to modify the semiconductor thin film on the interdigitated electrode. Specifically, drop the mixed solution onto the surface of the interdigitated electrode, and place it on a spin coater to form a uniform film on the surface of the interdigitated electrode. The spin coating and film formation conditions are 2000 r and 120 s. After completion, an interdigitated electrode uniformly modified with a PEDOT:PSS thin film can be obtained.

[0048] S300: Anneal the modified interdigitated electrode Perform post-treatment on the electrode obtained by the above high-temperature treatment: Under the protection of nitrogen, heat the PEDOT:PSS modified interdigitated electrode to 120 °C by a tube furnace, maintain the high temperature treatment for 20 min, and then perform programmed cooling.

[0049] The equivalent circuit of the ion circuit of the above organic electrochemical transistor when applying a double-pulse voltage is as Figure 1 shown, where the working electrode is the gate electrode.

[0050] Test experiment: 1. To confirm the feasibility of constructing a synaptic-like organic electrochemical transistor by the above method, the inventors conducted double-pulse inhibition tests and double-exponential function fittings on it, and the results are shown in Figure 2 .

[0051] Dual-pulse inhibition process: Insert the Ag / AgCl electrode and the interdigital electrode modified with the modified organic polymer semiconductor material into the phosphate buffer solution. Voltages of 0 V and -0.3 V are applied to the source and drain of the numerical source meter respectively, and a dual-pulse voltage is applied to the gate. The voltage value is 0.3 V, the single-pulse duration is 100 ms, and the pulse interval is 100 ms. The difference in the channel current during the two pulses is measured, referring to Figure 2 A.

[0052] Set the pulse intervals to vary from 40 ms to 2000 ms respectively, and calculate the conductance difference (ΔG = ΔI / V ds ) from the measured pulse current difference, and perform a double-exponential function fitting to obtain the decay curve, referring to Figure 2 B.

[0053] As can be seen from Figure 2 A, after applying a dual-pulse voltage to the gate, two current peaks with a difference in the drain current appear, indicating that the neuromorphic device can achieve the synaptic-like function of dual-pulse inhibition.

[0054] As can be seen from Figure 2 B, when the pulse interval of the gate is increased, the difference in the drain current decreases, indicating that the device can mimic the short-term plasticity function of the synapse.

[0055] 2. To explore the influence of different gates on the retention time of the device, subsequently, a bare glassy carbon electrode, a glassy carbon electrode modified with carbon nanotubes, a glassy carbon electrode modified with the modified organic polymer semiconductor material PEDOT:PSS, and an Ag / AgCl electrode are used as gates respectively to conduct tests on short-term synaptic plasticity and fit out the retention time, referring to Figure 3 .

[0056] As can be seen from Figure 3 , different retention times can be obtained by using different gates, indicating that there is a relationship between the retention time of the device and the type of gate. In addition, due to the small capacitance of the bare glassy carbon electrode and weak regulation effect, its decay curve is too scattered to calculate the retention time, and the signal needs to be further amplified before calculating the retention time.

[0057] 3. To study the factors of different gates regulating the retention time, the electrochemical impedance spectra of each part of the device are measured in a three-electrode system in PBS phosphate buffer solution through an Autolab workstation, and the capacitance value is obtained by fitting the Nyquist diagram. The bare glassy carbon electrode (referring to Figure 4 A), the glassy carbon electrode modified with carbon nanotubes (referring to Figure 4 B), the glassy carbon electrode modified with the modified organic polymer semiconductor material PEDOT:PSS (referring to Figure 4 C), and the channel of the interdigital electrode modified with PEDOT:PSSFigure 4 D).

[0058] As can be seen from Figure 4 , there are differences in the capacitances of different gates, and the capacitance size is positively correlated with the retention time. This shows that the gate capacitance can regulate the retention time of the device and mimic different neuromorphic functions.

[0059] 4. To illustrate the regulation ability of the capacitance on the channel current, the inventors respectively drew schematic diagrams of the distribution of the gate voltage in the ion circuit when using the polarized electrode (refer to Figure 5 A) and the non-polarized electrode (refer to Figure 5 B) as the gate.

[0060] As can be seen from Figure 5 A and Figure 5 B, the electric field intensities generated at the interface between the electrolyte and the electrolyte solution from strong to weak are: the Ag / AgCl electrode, the glassy carbon electrode modified with the modified organic polymer semiconductor material PEDOT:PSS, the glassy carbon electrode modified with carbon nanotubes, and the bare glassy carbon electrode.

[0061] 5. To further verify that the gate capacitance can regulate the plasticity of the neuromorphic device, the inventors studied the changes in the gate current and the channel current when the device was turned on and off at the transient time scale. This transient process can illustrate the influence of the gate capacitance on the plasticity of the neuromorphic device by the speed of ion injection and outflow from the channel, refer to Figure 6 . During the process of the device performing pulses and stopping the pulses after a period of time, a 4-ms interval was taken for hyperbolic function fitting to calculate the time constants of the gate current and the channel current, refer to Figure 7 .

[0062] As can be seen from Figure 6 , Figure 7 , the time constant of the glassy carbon electrode modified with the modified organic polymer semiconductor material PEDOT:PSS is longer than that of the glassy carbon electrode modified with carbon nanotubes. This is consistent with the results of the capacitance tests of the two, indicating that the neuromorphic device formed by the former has a better hysteresis effect and a longer short-term synaptic plasticity.

[0063] 6. To better represent the regulation of the channel ions by the gate capacitance and thus affect the plasticity of the device, the inventors analyzed this process by drawing a schematic diagram, refer to Figure 8 .

[0064] As can be seen from Figure 8 , when the gate capacitance is large, the gate voltage is mainly at the interface between the electrolyte solution and the channel, generating a large electric field that causes cations to gather at the channel, and combine with PEDOT +Dedoping occurs, causing the current to drop more. When the gate voltage is removed, due to the large gate capacitance, only a small portion of the anions at the gate return to the channel to dope, so the channel current recovers less. When the second pulse voltage is applied, the cations continue to cause the channel current to drop, and finally the difference between the two pulse currents is large. Similarly, when the gate capacitance is small, the current difference is small. And as the pulse interval time is lengthened, this relaxation effect caused by the gate capacitance is more significant, so when the gate capacitance is large, the retention time is longer.

[0065] Although the present invention has been described in detail with general descriptions and specific embodiments above, based on the present invention, some modifications or improvements can be made, which are obvious to those skilled in the art. Therefore, these modifications or improvements made without departing from the spirit of the present invention all fall within the scope of the present invention claimed.

Claims

1. A method for simulating neuron behavior using an organic electrochemical transistor, comprising: The gate of the organic electrochemical transistor is used as the presynaptic membrane, and the channel is used as the postsynaptic membrane. Under the drive of the gate double pulse voltage, ions in the electrolyte solution are doped and dedoped into the channel to simulate neurotransmitters and realize information conduction. The method achieves the regulation of short-term synaptic plasticity by adjusting the gate capacitance.

2. The method according to claim 1, characterized in that The short-term synaptic plasticity is characterized by retention time; the retention time refers to the interval time required for the first pulse to have no effect on the second pulse when a double pulse voltage is applied to the gate; the gate capacitance is positively correlated with the retention time.

3. The method according to claim 1 or 2, characterized in that: The regulation mechanism is as follows: in the ion circuit of the neuromorphic transistor, the gate voltage drop will affect the difference in the electric field, so that the ions in the solution migrate and gather in the channel, which is different from the doping of the organic polymer semiconductor material, thereby regulating the channel current; when the double pulse voltage is applied, the capacitance of the gate can not only affect the voltage drop, but its adsorption ability of ions will cause the movement of ions to have a hysteresis effect, thereby realizing the regulation of neuromorphic functional plasticity.

4. The method according to claim 3, characterized in that The gate is selected from one or more of a Ag / AgCl electrode, a bare glassy carbon electrode, a glassy carbon electrode modified with carbon nanotubes, and a glassy carbon electrode modified with a modified organic polymer semiconductor material PEDOT:PSS.

5. A neuromorphic organic electrochemical transistor comprising: Substrate, gate, electrolyte solution, channel, source and drain; The gate is a capacitance-adjustable gate capable of regulating short-term synaptic plasticity by the method according to any one of claims 1 to 4.

6. The neuromorphic organic electrochemical transistor according to claim 5, characterized in that The gate is selected from one or more of an Ag / AgCl electrode, a glassy carbon electrode modified with carbon nanotubes, and a glassy carbon electrode modified with a modified organic polymer semiconductor material PEDOT:PSS; The two ends of the channel are connected to the source and drain respectively to form interdigital electrodes; wherein the material of the channel is alumina ceramic, and its size is length: 10~100μm × width: 0.1~1cm; the source and drain are gold electrodes, and their thickness is 1~10μm; The interdigitated electrode surface is modified with a semiconductor film; the semiconductor film is formed by a modified organic semiconductor polymer mixed solution; The substrate is alumina ceramic.

7. A neuromorphic device, characterized in that A neuromorphic organic electrochemical transistor comprising the neuromorphic organic electrochemical transistor according to claim 5 or 6.

8. The neuromorphic device according to claim 7, characterized in that The device is a simulated synaptic device.

9. A method for testing the short-term plasticity retention time of a neuromorphic transistor according to claim 5 or 6, comprising: The gate is used as the working electrode, and the source, drain and channel are used as interdigital electrodes. The working electrode and the interdigital electrodes are placed in an electrolyte solution, and a double pulse voltage is applied to the gate to simulate the double pulse behavior of synaptic plasticity, and the retention time is fitted.

10. The testing method according to claim 8, characterized in that: The gate is selected from one or more of an Ag / AgCl electrode, a bare glassy carbon electrode, a glassy carbon electrode modified with carbon nanotubes, and a glassy carbon electrode modified with a modified organic polymer semiconductor material PEDOT:PSS; The operating parameters of the double pulse voltage are: a single pulse duration of 10 to 100 ms, a pulse voltage value of 0.1 to 0.5 V, an interval between two pulses ranging from 20 ms to 1000 ms, the source is grounded, and a constant voltage of -0.1 to 0.5 V is applied to the drain.

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