A method for preparing a spider silk memristor for simulating neural synapses

Abstract

The invention belongs to the technical field of memristors, and relates to a method for preparing a spider silk memristor for simulating neural synapses, specifically: after coating a NaOH-spider silk protein solution on a conductive layer to obtain a functional layer, an electrode layer is deposited on the functional layer to obtain a spider silk memristor for simulating neural synapses; the preparation process of the NaOH-spider silk protein solution is: after dissolving degummed spider silk in a NaOH aqueous solution, directly filtering and centrifuging to obtain a NaOH-spider silk protein solution, the concentration of the NaOH aqueous solution is 50-200mM. The memristor prepared by the method of the present invention has bionic neural synaptic characteristics, stable signal transmission, and can realize multiple stable erasing processes from a high resistance state to a low resistance state, thereby significantly improving the stability, durability and consistency of the device.

Description

Technical Field

[0001] The present invention belongs to the technical field of memristors, and in particular relates to a method for preparing a spider silk memristor for simulating neural synapses. Background Art

[0002] The reason why the brain exhibits complex dynamics and excellent adaptability is mainly attributed to the precise connection and efficient operation between neurons. Correspondingly, brain-like neuromorphic devices based on memristors have shown great potential in simulating the functions of human brain synapses due to their high similarity to the biological nervous system. Compared with inorganic materials, biomaterials used to make memristors have opened up broad prospects in the field of biomedical applications due to their excellent biocompatibility, flexibility and unique electrical properties.

[0003] However, the development of bio-memristors faces many challenges, such as material instability and poor cycle stability. In order to overcome these problems, researchers usually try to dope other materials in the functional layer to promote the formation of conductive paths and thus improve device performance. However, due to the inherent characteristics of the materials themselves, it is often difficult to perfectly integrate the functional layer materials and doped materials, resulting in the performance improvement effect not being as significant as expected.

[0004] In this context, spider silk protein, as a unique natural biomaterial, stands out for its high strength, toughness and unique three-dimensional spatial network structure; these properties make memristors made of spider silk protein excel in mechanical stability and durability.

[0005] Patent application CN110752294A proposes a method for preparing a flexible biological memristor for synaptic biomimetic, wherein silkworm cocoons are sequentially degummed, dissolved, dialyzed and concentrated to obtain a silk fibroin aqueous solution, a metal salt is then added to the silk fibroin aqueous solution to obtain a mixed solution, and the mixed solution is then coated on a conductive layer to obtain a flexible biological memristor. However, in this process, since the silk fibroin solution may undergo structural changes during the preparation process, and after the silk fibroin is mixed with the metal salt, some metal ions may not match the binding sites of the silk fibroin, the interaction between the metal ions and the protein is insufficient, and most of the metal ions are in a free state, which affects the stability of the conductive path of the memristor, so that the cycle stability and durability of the memristor obtained by this method are still not ideal. The preparation method of the reference patent application CN110752294A cannot produce a spider silk memristor with excellent cycle stability and durability.

[0006] Therefore, it is necessary to propose a new method to prepare spider silk memristors with excellent cycling stability and durability. Summary of the invention

[0007] The purpose of the present invention is to solve the problems in the prior art and to provide a method for preparing a spider silk memristor for simulating neural synapses.

[0008] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0009] A method for preparing a spider silk memristor for simulating neural synapses, comprising coating a NaOH-spider silk protein solution on a conductive layer to obtain a functional layer, and then depositing an electrode layer on the functional layer to obtain a spider silk memristor for simulating neural synapses;

[0010] The preparation process of NaOH-spider silk protein solution is as follows: after dissolving the degummed spider silk in the NaOH aqueous solution, it does not need to be dialyzed, but is directly filtered and centrifuged to obtain the NaOH-spider silk protein solution, and the concentration of the NaOH aqueous solution is 50-200 mM.

[0011] The spider silk memristor method for simulating neural synapses of the present invention allows metal ions to bind to proteins while dissolving proteins, and the metal ions can be evenly dispersed in the structural network of the protein, so that it is no longer in a messy state. After applying voltage to the memristor, a stable conductive path can be formed, which reduces the power consumption of the memristor and improves the cycle stability and durability of the memristor. The present invention controls the concentration of the NaOH aqueous solution to be 50-200 mM, because if the concentration of the NaOH aqueous solution is too low, the spider silk cannot be completely dissolved, affecting the yield of spider silk protein, and too little spider silk protein content in the solution will affect the stability and durability of the device; if the concentration of the NaOH aqueous solution is too high, the crystal content in the device is too much, which will affect the formation of the conductive path and the transmission of carriers.

[0012] As the preferred technical solution:

[0013] In the method for preparing a spider silk memristor for simulating neural synapses as described above, the concentration of the NaOH aqueous solution is 100 mM.

[0014] In the method for preparing a spider silk memristor for simulating neural synapses as described above, the mass ratio of degummed spider silk to NaOH aqueous solution is 1:30-50.

[0015] As described above, a method for preparing a spider silk memristor for simulating neural synapses comprises the following steps of preparing degummed spider silk: boiling the spider silk in a Na2CO3 aqueous solution for 2 to 3 times, and then washing the degummed spider silk with deionized water, wherein the concentration of the Na2CO3 aqueous solution is 0.2 to 0.5 wt %.

[0016] In the preparation method of a spider silk memristor for simulating neural synapses as described above, the concentration of the Na2CO3 aqueous solution is 0.5wt%; the concentration of the Na2CO3 aqueous solution and the degumming rate of spider silk are nonlinearly related. When the concentration of the Na2CO3 aqueous solution is in the range of 0.2~0.5wt%, the degumming rate of spider silk increases with the increase of the concentration of the Na2CO3 aqueous solution. After that, the concentration of the Na2CO3 aqueous solution continues to increase, but the degumming rate of spider silk remains basically unchanged. Therefore, it is preferred to use a Na2CO3 aqueous solution with a concentration of 0.5wt%.

[0017] In the method for preparing a spider silk memristor for simulating neural synapses as described above, the thickness of the functional layer is 40-50 nm. The thickness of the functional layer should not be too high, otherwise it will make it difficult for the device to form a conductive path and the power consumption of the device will increase.

[0018] In the method for preparing a spider silk memristor for simulating neural synapses as described above, the coating is formed by repeated spin coating, the number of repetitions is 2 to 3 times, the spin coating speed is 1000 to 1500 rpm, and the single spin coating time is 10 to 20 s.

[0019] In order to obtain a functional layer with a smaller thickness, the spin coating time and the spin coating speed need to be set larger within a reasonable range. The NaOH-spider silk protein solution has good hydrophilicity and adhesion, and can be well attached to the surface of the conductive layer. There is no need to worry about all the solution being thrown away by an excessively high spin coating speed, which provides a guarantee for increasing the spin coating speed.

[0020] In the method for preparing a spider silk memristor for simulating neural synapses as described above, the conductive layer is a W (tungsten) film or an ITO film, and the thickness of the conductive layer is 100-200 nm.

[0021] In the method for preparing a spider silk memristor for simulating neural synapses as described above, the conductive layer is supported by a substrate, the substrate is a PET film or glass, and the thickness of the substrate is 0.5-1 mm.

[0022] In the method for preparing a spider silk memristor for simulating neural synapses as described above, the deposition is carried out by electron beam evaporation or thermal evaporation, the electrode layer is an Ag electrode layer or an Al electrode layer, and the thickness of the electrode layer is 100-120 nm.

[0023] A method for preparing a spider silk memristor for simulating neural synapses as described in any of the above items, wherein the maximum cycle period of the spider silk memristor for simulating neural synapses is m times, the average SET voltage of the m cycle periods is 0.9~1.5V, the standard deviation is 0.06~0.15V, and m is 150~250.

[0024] The more cycles there are, the better the cycle stability of the memristor is. The smaller the SET voltage is, the lower the power consumption of the memristor is. The smaller the standard deviation is, the better the stability and durability of the memristor is, and the smaller the fluctuation in each cycle is.

[0025] Beneficial effects:

[0026] (1) The method of the present invention is to obtain a uniform solution of the system and prepare a memristor by directly dissolving spider silk, and the process is simple and easy to operate;

[0027] (2) A method for preparing a spider silk memristor for simulating neural synapses according to the present invention. The prepared memristor has bionic neural synaptic characteristics, stable signal transmission, and realizes multiple stable erasing processes from a high resistance state to a low resistance state, which significantly improves the stability, durability and consistency of the memristor;

[0028] (3) The spider silk memristor prepared by the present invention has a low operating voltage and reduced power consumption, which can improve data storage efficiency and promote the development of memristor devices towards high efficiency and multifunctionality. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 The resistance switching behaviors of the spider silk memristor for simulating neural synapses prepared in Example 1 in the 1st and 250th cycles;

[0030] Figure 2 The resistance switching behaviors of 30 spider silk memristors for simulating neural synapses made by the method of Example 1 in the first cycle. DETAILED DESCRIPTION

[0031] The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms fall within the scope limited by the appended claims of the application equally.

[0032] Detection methods of relevant indicators in the embodiments and comparative examples:

[0033] Cycle period, average SET voltage, and standard deviation: The Keithley 4200A-SCS semiconductor tester was used to measure the memristor's memristor characteristics by applying a continuous scanning voltage in DC mode at room temperature (25°C) and normal pressure. The test results were presented in the form of IV curves. The IV curves of different cycle periods had good repeatability, indicating that the device had good cycle stability. The spider silk memristor transitioned from HRS (high resistance state) to LRS (low resistance state) and then from LRS to HRS as one cycle. The voltage when HRS transitioned to LRS in each cycle was the SET voltage. The average SET voltage and standard deviation of n cycles were calculated based on the test results. The smaller the standard deviation, the better the stability and durability of the memristor.

[0034] The types of spider silk applicable to the present invention are not limited, and the following embodiments and comparative examples are only described using the Jingzhao trichome spider silk as an example.

[0035] Example 1

[0036] A method for preparing a spider silk memristor for simulating neural synapses is as follows:

[0037] (1) Prepare the raw materials:

[0038] Spider silk;

[0039] Na2CO3 aqueous solution: concentration 0.5wt%;

[0040] Deionized water;

[0041] NaOH aqueous solution: concentration 100 mM;

[0042] Conductive layer: ITO film with a thickness of 185nm, supported by a glass substrate with a thickness of 0.7mm;

[0043] (2) Preparation of degummed spider silk:

[0044] The spider silk was boiled twice in a Na2CO3 aqueous solution and then washed with deionized water to obtain degummed spider silk;

[0045] (3) Preparation of NaOH-spider silk protein solution:

[0046] After dissolving the degummed spider silk in a NaOH aqueous solution at a mass ratio of 1:50, the degummed spider silk is directly filtered and centrifuged without dialysis to obtain a NaOH-spider silk protein solution;

[0047] (4) Preparation of memristor:

[0048] After coating the NaOH-spider silk protein solution on the conductive layer to obtain a functional layer with a thickness of 45 nm, an Ag electrode layer with a thickness of 100 nm was deposited on the functional layer by electron beam evaporation, thereby obtaining a spider silk memristor for simulating neural synapses;

[0049] The coating was prepared by repeated spin coating, with the number of repetitions being 3 times, the spin coating speed being 1500 rpm, and the single spin coating time being 15 s.

[0050] The spider silk memristor for simulating neural synapses has a maximum cycle of 250 times, an average SET voltage of 0.9V and a standard deviation of 0.06V after 250 cycles. The resistance switching behavior of the spider silk memristor for simulating neural synapses in the 1st and 250th cycles is shown in Figure 2. Figure 1 As shown in the figure, it can be seen that the spider silk-based memristor has good cycling stability.

[0051] After 30 spider silk memristors for simulating neural synapses were prepared by the method of this embodiment, they were tested respectively to obtain 30 IV curves. The results are shown in Figure 2 ;Depend on Figure 2 It can be seen that the 30 spider silk memristors for simulating neural synapses exhibit good stability, indicating that the spider silk memristors for simulating neural synapses prepared by the method of the present invention exhibit high consistency and reliability in performance.

[0052] Comparative Example 1

[0053] A method for preparing a spider silk memristor for simulating neural synapses is basically the same as that in Example 1, except that the concentration of the NaOH aqueous solution used in this comparative example is 30 mM.

[0054] The spider silk memristor finally produced for simulating neural synapses has a maximum cycle period of 50 times, an average SET voltage of 1.6V after 50 cycles, and a standard deviation of 0.5V.

[0055] Compared with Example 1, the spider silk memristor simulating neural synapses prepared in Comparative Example 1 can only be cycled 50 times (poor cycle stability), with a high average SET voltage, a large standard deviation, and increased device power consumption; this is because the concentration of the NaOH aqueous solution in Comparative Example 1 is too low, the amount of spider silk that can be dissolved is too small, the yield of spider silk protein is too low, and the content of spider silk protein in the solution is too low, which will affect the stability and durability of the device.

[0056] Comparative Example 2

[0057] A method for preparing a spider silk memristor for simulating neural synapses is basically the same as that in Example 1, except that the concentration of the NaOH aqueous solution used in this comparative example is 250 mM.

[0058] The spider silk memristor finally produced for simulating neural synapses has a maximum cycle period of 80 times, an average SET voltage of 1.73V after 80 cycles, and a standard deviation of 0.46V.

[0059] Compared with Example 1, the spider silk memristor simulating neural synapses prepared in Comparative Example 2 can only be cycled 80 times (poor cycle stability), with a high average SET voltage, a large standard deviation, and increased device power consumption; this is because the concentration of the NaOH aqueous solution in Comparative Example 2 is too high, resulting in too much crystal content in the device, which affects the formation of the conductive path and the transmission of carriers, and ultimately makes the stability and durability of the memristor prepared in Comparative Example 2 worse.

[0060] Example 2

[0061] A method for preparing a spider silk memristor for simulating neural synapses is as follows:

[0062] (1) Prepare the raw materials:

[0063] Spider silk;

[0064] Na2CO3 aqueous solution: concentration 0.5wt%;

[0065] Deionized water;

[0066] NaOH aqueous solution: concentration 50 mM;

[0067] Conductive layer: ITO film with a thickness of 185nm, supported by a glass substrate with a thickness of 0.7mm;

[0068] (2) Preparation of degummed spider silk:

[0069] The spider silk was boiled twice in a Na2CO3 aqueous solution and then washed with deionized water to obtain degummed spider silk;

[0070] (3) Preparation of NaOH-spider silk protein solution:

[0071] After dissolving the degummed spider silk in a NaOH aqueous solution at a mass ratio of 1:50, the degummed spider silk is directly filtered and centrifuged without dialysis to obtain a NaOH-spider silk protein solution;

[0072] (4) Preparation of memristor:

[0073] After coating the NaOH-spider silk protein solution on the conductive layer to obtain a functional layer with a thickness of 50 nm, an Ag electrode layer with a thickness of 120 nm was deposited on the functional layer by electron beam evaporation, thereby obtaining a spider silk memristor for simulating neural synapses;

[0074] The coating was prepared by repeated spin coating, with the number of repetitions being 3 times, the spin coating speed being 1000 rpm, and the single spin coating time being 15 s.

[0075] The spider silk memristor finally produced for simulating neural synapses has a maximum cycle period of 180 times, an average SET voltage of 1V after 180 cycles, and a standard deviation of 0.12V.

[0076] Example 3

[0077] A method for preparing a spider silk memristor for simulating neural synapses is as follows:

[0078] (1) Prepare the raw materials:

[0079] Spider silk;

[0080] Na2CO3 aqueous solution: concentration 0.3wt%;

[0081] Deionized water;

[0082] NaOH aqueous solution: concentration 50 mM;

[0083] Conductive layer: W film with a thickness of 100 nm, supported by a glass substrate with a thickness of 0.7 mm;

[0084] (2) Preparation of degummed spider silk:

[0085] The spider silk was boiled twice in a Na2CO3 aqueous solution and then washed with deionized water to obtain degummed spider silk;

[0086] (3) Preparation of NaOH-spider silk protein solution:

[0087] After dissolving the degummed spider silk in a NaOH aqueous solution at a mass ratio of 1:50, the degummed spider silk is directly filtered and centrifuged without dialysis to obtain a NaOH-spider silk protein solution;

[0088] (4) Preparation of memristor:

[0089] After coating the NaOH-spider silk protein solution on the conductive layer to obtain a functional layer with a thickness of 47 nm, an Al electrode layer with a thickness of 100 nm was deposited on the functional layer by electron beam evaporation to obtain a spider silk memristor for simulating neural synapses.

[0090] The coating was prepared by repeated spin coating, with the number of repetitions being 2, the spin coating speed being 1000 rpm, and the single spin coating time being 10 s.

[0091] The spider silk memristor finally produced for simulating neural synapses has a maximum cycle period of 150 times, an average SET voltage of 1.2V after 150 cycles, and a standard deviation of 0.15V.

[0092] Example 4

[0093] A method for preparing a spider silk memristor for simulating neural synapses is as follows:

[0094] (1) Prepare the raw materials:

[0095] Spider silk;

[0096] Na2CO3 aqueous solution: concentration 0.4wt%;

[0097] Deionized water;

[0098] NaOH aqueous solution: concentration 70mM;

[0099] Conductive layer: ITO film with a thickness of 185nm, supported by a PET substrate with a thickness of 0.8mm;

[0100] (2) Preparation of degummed spider silk:

[0101] The spider silk was boiled in a Na2CO3 aqueous solution for three times and then washed with deionized water to obtain degummed spider silk;

[0102] (3) Preparation of NaOH-spider silk protein solution:

[0103] After dissolving the degummed spider silk in a NaOH aqueous solution at a mass ratio of 1:30, the degummed spider silk is directly filtered and centrifuged without dialysis to obtain a NaOH-spider silk protein solution;

[0104] (4) Preparation of memristor:

[0105] After coating the NaOH-spider silk protein solution on the conductive layer to obtain a functional layer with a thickness of 43 nm, a Ag electrode layer with a thickness of 120 nm was deposited on the functional layer by thermal evaporation to obtain a spider silk memristor for simulating neural synapses;

[0106] The coating was prepared by repeated spin coating, with the number of repetitions being 2, the spin coating speed being 1500 rpm, and the single spin coating time being 10 s.

[0107] The spider silk memristor finally produced for simulating neural synapses has a maximum cycle period of 170 times, an average SET voltage of 1.33V after 170 cycles, and a standard deviation of 0.11V.

[0108] Example 5

[0109] A method for preparing a spider silk memristor for simulating neural synapses is as follows:

[0110] (1) Prepare the raw materials:

[0111] Spider silk;

[0112] Na2CO3 aqueous solution: concentration 0.2wt%;

[0113] Deionized water;

[0114] NaOH aqueous solution: concentration 160mM;

[0115] Conductive layer: W film with a thickness of 100 nm, supported by a PET substrate with a thickness of 1 mm;

[0116] (2) Preparation of degummed spider silk:

[0117] The spider silk was boiled in a Na2CO3 aqueous solution for three times and then washed with deionized water to obtain degummed spider silk;

[0118] (3) Preparation of NaOH-spider silk protein solution:

[0119] After dissolving the degummed spider silk in a NaOH aqueous solution at a mass ratio of 1:40, the degummed spider silk is directly filtered and centrifuged without dialysis to obtain a NaOH-spider silk protein solution;

[0120] (4) Preparation of memristor:

[0121] After coating the NaOH-spider silk protein solution on the conductive layer to obtain a functional layer with a thickness of 40 nm, a 100 nm thick Al electrode layer is deposited on the functional layer by thermal evaporation to obtain a spider silk memristor for simulating neural synapses.

[0122] The coating was prepared by repeated spin coating, with the number of repetitions being 3 times, the spin coating speed being 1500 rpm, and the single spin coating time being 20 s.

[0123] The spider silk memristor finally produced for simulating neural synapses has a maximum cycle period of 150 times, an average SET voltage of 1.46V after 150 cycles, and a standard deviation of 0.1V.

[0124] Example 6

[0125] A method for preparing a spider silk memristor for simulating neural synapses is as follows:

[0126] (1) Prepare the raw materials:

[0127] Spider silk;

[0128] Na2CO3 aqueous solution: concentration 0.5wt%;

[0129] Deionized water;

[0130] NaOH aqueous solution: concentration 200 mM;

[0131] Conductive layer: ITO film with a thickness of 200nm, the conductive layer is supported by a glass substrate with a thickness of 1mm Conductive layer:

[0132] (2) Preparation of degummed spider silk:

[0133] The spider silk was boiled in a Na2CO3 aqueous solution for three times and then washed with deionized water to obtain degummed spider silk;

[0134] (3) Preparation of NaOH-spider silk protein solution:

[0135] After dissolving the degummed spider silk in a NaOH aqueous solution at a mass ratio of 1:30, the degummed spider silk is directly filtered and centrifuged without dialysis to obtain a NaOH-spider silk protein solution;

[0136] (4) Preparation of memristor:

[0137] After coating the NaOH-spider silk protein solution on the conductive layer to obtain a functional layer with a thickness of 40 nm, a 120 nm thick Al electrode layer is deposited on the functional layer by thermal evaporation to obtain a spider silk memristor for simulating neural synapses;

[0138] The coating was prepared by repeated spin coating, with the number of repetitions being 3 times, the spin coating speed being 1500 rpm, and the single spin coating time being 20 s.

[0139] The spider silk memristor finally produced for simulating neural synapses has a maximum cycle period of 200 times, an average SET voltage of 1.5V after 200 cycles, and a standard deviation of 0.15V.

Claims

1. A method for preparing a spider silk memristor for simulating neural synapses, characterized in that: After coating the NaOH-spider silk protein solution on the conductive layer to obtain a functional layer, an electrode layer is deposited on the functional layer to obtain a spider silk memristor for simulating neural synapses; The preparation process of NaOH-spider silk protein solution is as follows: after dissolving the degummed spider silk in a NaOH aqueous solution, directly filtering and centrifuging to obtain a NaOH-spider silk protein solution, wherein the concentration of the NaOH aqueous solution is 50-200 mM; The maximum cycle period of the spider silk memristor used to simulate neural synapses is m times, the average SET voltage of m cycles is 0.9~1.5V, the standard deviation is 0.06~0.15V, and m is 150~250.

2. The method for preparing a spider silk memristor for simulating neural synapses according to claim 1, characterized in that: The concentration of the NaOH aqueous solution was 100 mM.

3. The method for preparing a spider silk memristor for simulating neural synapses according to claim 1, characterized in that: The mass ratio of degummed spider silk to NaOH aqueous solution is 1:30~50.

4. The method for preparing a spider silk memristor for simulating neural synapses according to claim 1, characterized in that: The preparation process of degummed spider silk is as follows: the spider silk is boiled in a Na2CO3 aqueous solution for 2 to 3 times, and then washed with deionized water to obtain the degummed spider silk. The concentration of the Na2CO3 aqueous solution is 0.2 to 0.5 wt%.

5. The method for preparing a spider silk memristor for simulating neural synapses according to claim 4, characterized in that: The concentration of the Na2CO3 aqueous solution is 0.5wt%.

6. The method for preparing a spider silk memristor for simulating neural synapses according to claim 1, characterized in that: The thickness of the functional layer is 40~50nm.

7. The method for preparing a spider silk memristor for simulating neural synapses according to claim 6, characterized in that: The coating is formed by repeated spin coating, the number of repetitions is 2 to 3 times, the spin coating speed is 1000 to 1500 rpm, and the single spin coating time is 10 to 20 s.

8. The method for preparing a spider silk memristor for simulating neural synapses according to claim 1, characterized in that: The conductive layer is a W film or an ITO film, and the thickness of the conductive layer is 100-200 nm; the conductive layer is supported by a substrate, and the substrate is a PET film or glass, and the thickness of the substrate is 0.5-1 mm.

9. The method for preparing a spider silk memristor for simulating neural synapses according to claim 1, characterized in that: The deposition is carried out by electron beam evaporation or thermal evaporation. The electrode layer is an Ag electrode layer or an Al electrode layer. The thickness of the electrode layer is 100-120 nm.

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