High-durability fibrous SF-based memristor and preparation method thereof

Abstract

The invention belongs to the technical field of electronic devices, and relates to a high-durability fibrous SF-based memristor and a preparation method thereof, after metal nanoparticles and an SF layer are sequentially deposited on the surface of a bottom electrode fiber, the bottom electrode fiber is in lap joint with a top electrode fiber, and the high-durability fibrous SF-based memristor is obtained. The memristor has excellent cycling stability, uniform performance among devices and long resistance retention time, and the SF-based fibrous memristor is endowed with photoelectric property and thermoelectric property, so that the memristor is beneficial to development towards the direction of intelligent wearable electronic devices.

Description

Technical Field

[0001] The present invention belongs to the technical field of electronic devices, and relates to a highly durable fibrous SF-based memristor and a preparation method thereof. Background Art

[0002] With the rapid development of artificial intelligence technology, the demand for computing efficiency and speed is increasing day by day. The traditional separated memory and computing architecture has been difficult to meet the requirements at the present stage. As a device that can process and store information simultaneously, the memristor has become the key to solving this problem due to its low power consumption and high-efficiency computing characteristics. The working principle of the memristor is based on the migration of carriers inside the material, and its resistance state is determined by the distribution of carriers inside the material. This characteristic is very similar to the function of biological neural synapses, making the memristor have great potential in simulating the functions of human brain neural synapses, especially in the construction of brain-like computing systems and the field of artificial intelligence.

[0003] In order to better simulate the functions of human brain synapses, the research and development of memristive devices that can respond to multiple stimuli and the improvement of the spatio-temporal stability of memristors have become current research hotspots. In recent years, flexible electronic components have been considered an effective method for realizing wearable electronic systems due to their unique flexibility and light weight. As a natural polymer material, silk fibroin (SF) has good biocompatibility and degradability. Therefore, the SF-based memristor has the characteristics of flexibility and light weight and is suitable for integration into wearable devices, providing a new way to achieve high-performance flexible artificial synapses.

[0004] The literature (ACS Sens. 2024, 9, 5312-5321.) discloses a bionic artificial nociception alarm system based on fibrous bio-memristors. The functional layer of the memristor is an SF layer, which is prepared by an electrodeposition reaction. Although regular secondary structures of SF can be prepared on the fibers by electrodeposition, the formation and annihilation of conductive filaments cannot be fixed for a long time only by the action of microcrystals in SF. Therefore, the retention time of its high and low resistance states is only 1000 s. In addition, although the SF fiber bio-resistor constructed in this literature has a piezoresistive function, there is still much room for improvement in memristive stability and its functionality is single.

[0005] Patent application CN109326711A discloses a metal nanocluster-doped memristor and its preparation method. This metal nanocluster-doped memristor includes a top electrode, a resistive switching layer, and a bottom electrode. The resistive switching layer is located between the top electrode and the bottom electrode. The resistive switching layer is a resistive material thin film doped with metal nanoclusters, and the resistive material thin film is selected from one of metal oxide thin films, polymer thin films, and natural protein thin films. Although this patent strengthens the effect of the local electric field and improves the resistance switching characteristics by doping metal nanoclusters in SF, this preparation method cannot be simply applied to fibrous devices and has many limitations. For example, the large-scale contact of nanoparticles with the functional layer material or air may cause reactions to form unexpected phases such as low-conductivity compounds, reducing the switching performance, especially for SF-based biological protein materials, which reduces their durability; during repeated operations, the aggregation or migration of nanoparticles may lead to the degradation of the functional layer structure, resulting in a decrease in the cycle stability of the device and a shortening of the service life.

[0006] Therefore, it is necessary to study a highly durable fibrous SF-based memristor and its preparation method. Summary of the Invention

[0007] The purpose of the present invention is to solve the problems existing in the prior art and provide a highly durable fibrous SF-based memristor and its preparation method.

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

[0009] A preparation method of a highly durable fibrous SF-based memristor. After sequentially depositing metal nanoparticles and an electrodeposited SF layer on the surface of a bottom electrode fiber, it is overlapped with a top electrode fiber to obtain a highly durable fibrous SF-based memristor.

[0010] In the present invention, metal nanoparticles are first deposited on the fiber surface, and then an SF layer is electrodeposited. On the one hand, the metal nanoparticles deposited by electrochemical deposition are not only highly uniformly distributed and tightly combined with the electrode fiber, but also play a role in strengthening the local electric field; on the other hand, SF has repetitive amino acid sequences, and these sequences are prone to form specific secondary structures under certain conditions and then develop into microcrystalline structures. The local electric field existing around the metal nanoparticles can promote the nucleation of SF, form a large number of discretely distributed microcrystalline structures, and make the size of the microcrystals smaller and the size distribution narrower. In addition, the SF layer wraps the metal nanoparticle layer, playing a packaging role, effectively preventing the metal nanoparticles from contacting with air and oxidizing. Since the metal nanoparticles are tightly combined with the electrode fiber and only contact the bottom of the SF layer, the stability of the device can be effectively maintained, making it highly durable.

[0011] Taking the bottom electrode fiber as an Ag fiber and the top electrode fiber as an Ag fiber as an example, the working principle of the highly durable fibrous SF-based memristor of the present invention is described as follows:

[0012] At the beginning, the memristor is in the HRS (high resistance state). When an external electric field is applied, Ag atoms in the top electrode fiber are ionized into Ag + , and under the action of the electric field, Ag + passes through the SF layer and reaches the bottom electrode fiber. Since there are metal nanoparticles on the surface of the bottom electrode fiber and there is a local electric field around the metal nanoparticles, Ag + will migrate concentratedly onto the metal nanoparticles, capture the electrons of the bottom electrode fiber and be reduced to Ag atoms. As the redox process continues, the number of Ag atoms accumulated at the bottom electrode fiber gradually increases, contacts with the top electrode fiber to form a conductive filament, increases the conductivity of the memristor, and changes to the LRS (low resistance state), realizing the SET process. When an opposite voltage with sufficient intensity is applied, the conductive filament is dissolved and annihilated, reducing the conductivity of the memristor and restoring the HRS, realizing the RESET process.

[0013] "Cycle" is the conversion of HRS-LRS-HRS. The more cycles there are, the better the stability. Each time a "cycle" occurs, if the conductive filament is formed and annihilated at the same position, the cycle stability of the memristor can be improved.

[0014] During the SET process, first, the local electric field around the metal nanoparticles plays a role in guiding the formation of the conductive filament at the same position. As the conductive filament grows deeper into the SF layer, the effect of the local electric field weakens, and the fixing effect on the conductive filament weakens. At this time, due to the microcrystalline structure of the SF layer, the microcrystalline structure can fix the growth of the conductive filament between the microcrystals, enabling the conductive filament to continue to grow orderly in the SF layer, greatly improving the stability of the memristor.

[0015] During the RESET process, under the action of the reverse voltage, Ag atoms are oxidized and detached from the conductive filament and migrate towards the top electrode fiber. At the same time, the Joule heat effect and the electrochemical dissolution effect cause the conductive filament to dissolve and break orderly between the microcrystals, ultimately restoring the device to the HRS.

[0016] As a preferred technical solution:

[0017] A preparation method of a highly durable fibrous SF-based memristor as described above, wherein the average particle size of the metal nanoparticles is 20-40 nm, and the coverage rate of the metal nanoparticles on the surface of the bottom electrode fiber is 20-80%, that is, 20-80% of the surface area of the bottom electrode fiber is covered by the metal nanoparticles. The reasonable setting of the size and coverage rate of the metal nanoparticles can enable the local electric field at the metal nanoparticles to cooperate well with the microcrystalline structure of the SF layer, and fix the growth of the conductive filaments; the visible light absorption intensity of the metal nanoparticles is 0.10-0.18 a.u.

[0018] A preparation method of a highly durable fibrous SF-based memristor as described above, wherein the metal nanoparticles are SnSe nanoparticles, ZnS nanoparticles or NiS nanoparticles.

[0019] A preparation method of a highly durable fibrous SF-based memristor as described above, after sequentially depositing metal nanoparticles and electro-depositing the SF layer on the surface, the increased value of the radius of the bottom electrode fiber is 28-95 nm.

[0020] A preparation method of a highly durable fibrous SF-based memristor as described above, the diameter of the bottom electrode fiber is 100 nm - 1 mm; the diameter of the top electrode fiber is 100 nm - 1 mm.

[0021] A preparation method of a highly durable fibrous SF-based memristor as described above, the bottom electrode fiber is an Ag fiber, a Pt fiber, an Au fiber, an Al fiber, an Mg fiber or a Cu fiber; the top electrode fiber is an Ag fiber, a Pt fiber, an Au fiber, an Al fiber, an Mg fiber or a Cu fiber.

[0022] A preparation method of a highly durable fibrous SF-based memristor as described above, electro-deposition is used to deposit the metal nanoparticles. During electro-deposition, a saturated calomel electrode is used as the reference electrode, a platinum sheet electrode is used as the counter electrode, and the bottom electrode fiber is used as the working electrode. The three electrodes are inserted into the metal ion electrolyte for constant potential deposition. The deposition voltage is -0.5~-1.5 V, the deposition time is 30-90 s, and after deposition, ultrasonic treatment is carried out for 5-10 s and then dried; vapor deposition and magnetron sputtering can also be used to deposit the metal nanoparticles, but compared with electro-deposition, these methods cannot deposit on the fiber at one time (only 180-degree deposition on one side can be achieved during deposition), and will result in a smaller binding force between the metal nanoparticles and the bottom electrode fiber.

[0023] A preparation method of a highly durable fibrous SF-based memristor as described above. When electro-depositing the SF layer, connect Ag fiber, Pt fiber, Au fiber, Al fiber, Mg fiber or Cu fiber to the negative pole of a DC power supply, connect the bottom electrode fiber after depositing metal nanoparticles to the positive pole of the DC power supply, immerse the two fibers parallelly into the SF solution, and apply a voltage of 0.1 - 10 V for deposition for 500 - 7500 s.

[0024] The present invention also provides a highly durable fibrous SF-based memristor, which is prepared by using the preparation method of a highly durable fibrous SF-based memristor described in any one of the above; the HRS resistance value of the highly durable fibrous SF-based memristor is 12000 - 62000 Ω, the initial value of the SET voltage is 0.15 - 0.33 V, the LRS resistance value is 85 - 2500 Ω, and the working current is 10 -9 -10 -4 A, the erasable number of times exceeds 10 3 times; the resistance retention time of the highly durable fibrous SF-based memristor under HRS and LRS can both reach 6500 - 7500 s, and the reduction rate of the resistance retention time under HRS and LRS after storing for one month does not exceed 25%; the average SET voltage of the highly durable fibrous SF-based memristor in the 1st - 200th cycle period is 0.15 - 0.36 V, and the standard deviation is 0.02 - 0.04 V.

[0025] After repeated cyclic operations, the SET voltage of the highly durable fibrous SF-based memristor of the present invention can still remain stable, and the high and low resistance state retention degrees are relatively high for a long time, indicating that metal nanoparticles and SF microcrystals can stably improve the performance of the device, enabling it to be used and stored for a long time, which is closely related to the distribution and structure of metal nanoparticles and SF.

[0026] Invention mechanism:

[0027] In the present invention, an array of metal nanoparticles is constructed on a conductive fiber, and the orderly growth of conductive filaments is realized under the coordinated action of metal nanoparticles and SF microcrystals, thereby significantly improving the cycling stability. And under the stimulation of light and heat, the metal nanoparticles exhibit thermoelectric and optoelectronic responses. The specific reasons are as follows:

[0028] (1) The secondary structure of the pure SF solution film is mainly a random coil / helix structure. When used as a functional layer, the performance of the memristor fluctuates greatly, and certain post-treatment means are required to improve its structural regularity to enhance the memristive performance. Under the electro-deposition method, the secondary structure of the SF layer is mainly a β-sheet structure, and under the action of the local electric field at the metal nanoparticles, as the deposition time increases, the random structure in the SF layer gradually decreases, forming a large number of small-sized microcrystalline structures, which can effectively improve the cycling stability and retention time of the memristor.

[0029] (2) In the SF deposition layer, the microcrystals in SF have limited effect on the growth of fixed conductive filaments, making it difficult to ensure the cycling stability and uniformity among devices of the memristor. Since the metal nanoparticles of the present invention are located below the SF layer, under the action of an external electric field, the electric field at the metal nanoparticles is enhanced, especially at the top position of the metal nanoparticles. During the SET process, conductive filaments are easily formed at the metal nanoparticles, and with the coordinated action of the SF microcrystals, the conductive filaments can grow stably, changing from the HRS to the LRS. Applying a reverse electric field dissolves the conductive filaments and restores the HRS. Applying a forward electric field again can return to the previous LRS, realizing the cycling stability of the memristor.

[0030] (3) Durability is an important performance affecting the operation of the memristor. For SF-based memristors, SF may react when mixed and doped with inorganic materials, making SF unstable. At the same time, the simple doping of SF and inorganic materials is physically combined, and during long-term use, their distribution and structure are prone to change. However, the layered structure of the metal nanoparticles and SF deposited electrochemically separately in the present invention is chemically combined, which can achieve the long-term stable interaction between the metal nanoparticles and SF, thereby improving the durability of the device.

[0031] Beneficial effects:

[0032] (1) The present invention prepares a high-durability fibrous SF-based memristor by depositing metal nanoparticles on the bottom electrode fibers and electro-depositing an SF layer thereon. This method is simple and easy to operate, with low cost, and can effectively prepare a high-performance fibrous memristor with good cycling stability, uniform performance among devices, and a long resistance retention time.

[0033] (2) The present invention utilizes the local electric field around the metal nanoparticles to guide the orderly growth of conductive filaments in the SF layer, greatly improving the stability of the memristor. At the same time, the microcrystalline structure of the SF layer further fixes the growth position of the conductive filaments, enabling the conductive filaments to form and annihilate at the same position during both the SET and RESET processes, further enhancing the cycling stability.

[0034] (3) The SF material adopted in the present invention has good biocompatibility and degradability, making the prepared high-durability fibrous SF-based memristor suitable for integration into wearable devices, providing a new way for realizing high-performance flexible artificial synapses.

[0035] (4) The high-durability fibrous SF-based memristor prepared by the present invention also has multifunctionality, which is conducive to the development towards intelligent wearable electronic devices. Description of the Drawings

[0036] Figure 1Variation curve of voltage and current during the first cycle of the highly durable fibrous SF-based memristor of Example 2;

[0037] Figure 2 SEM image of the surface of Ag fiber a with metal nanoparticles deposited on the surface of Example 1;

[0038] Figure 3 UV-visible absorption spectrum of the metal nanoparticles of Example 3;

[0039] Figure 4 Resistance retention time of the highly durable fibrous SF-based memristor of Example 1 under HRS and LRS;

[0040] Figure 5 Resistance retention time of the highly durable fibrous SF-based memristor of Example 1 under HRS and LRS after being stored for one month. Detailed implementation manners

[0041] The present invention will be further described below in conjunction with specific implementation manners. It should be understood that these examples are only used to illustrate the present invention and not 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 also fall within the scope defined by the appended claims of this application.

[0042] Explanation of "cycle period" in each example: The highly durable fibrous SF-based memristor changing from HRS to LRS and then from LRS to HRS is recorded as 1 cycle period; the cycle test process of changing from HRS to LRS and then from LRS to HRS is as follows: in natural light (light intensity is 1.23W / m 2 ) environment, starting from 0V, gradually increasing the voltage to make the highly durable fibrous SF-based memristor change from HRS to LRS, and then gradually decreasing the voltage until the highly durable fibrous SF-based memristor recovers from LRS to HRS; in the first cycle, the resistance value when the highly durable fibrous SF-based memristor changes from HRS to LRS is the LRS resistance value (after the first cycle period, all are based on this resistance value at this time), and the voltage value at this time is the initial value of the SET voltage.

[0043] The following are the test methods for relevant performance indicators in each example and comparative example:

[0044] Size of metal nanoparticles: Fix the fiber deposited with metal nanoparticles to the electron microscope stage through conductive glue, and use a scanning electron microscope with the model Gemini SEM 560 to measure the size under an acceleration voltage of 3 kV.

[0045] SET voltage, operating current, and erasable times: Tested by a 4200A-SCS semiconductor tester of Keithley brand.

[0046] HRS resistance value, LRS resistance value: Measured by a B2901A precision power supply of KEYDIGHT brand in DC mode.

[0047] Resistance retention time: At 25°C and 0.1 MPa, use a 4200A-SCS semiconductor tester of Keithley brand to measure the memristive characteristics of the sample to be tested in DC mode. At a reading voltage of 0.0001 V, respectively measure the time when the resistance of the sample to be tested is stably maintained under HRS and LRS, which is the resistance retention time.

[0048] Visible light absorption intensity: Test the absorption intensity of the sample to be tested in the visible light region (wavelength 380 - 780 nm) by a U-T6 ultraviolet-visible spectrophotometer.

[0049] Example 1

[0050] A preparation method of a high-durability fibrous SF-based memristor, the specific steps are as follows:

[0051] (1) Preparation of materials;

[0052] Silkworm cocoons: Produced in Guiyang City, Guizhou Province;

[0053] Na2CO3 aqueous solution: Mass fraction is 0.5 wt%;

[0054] Deionized water;

[0055] Lithium bromide aqueous solution: Concentration is 9.3 mol / L;

[0056] Saturated calomel electrode;

[0057] Platinum sheet electrode;

[0058] Ag fibers a, Ag fibers b, Ag fibers c: All are Ag fibers with a diameter of 100 nm;

[0059] Metal ion electrolyte: pH value is 2 (adjusted by a 0.1 M HCl aqueous solution), prepared from a stannous chloride aqueous solution and a sodium selenite aqueous solution with a volume ratio of 1:1, and the concentrations of the stannous chloride aqueous solution and the sodium selenite aqueous solution are both 2 mM;

[0060] (2) Preparation of SF solution;

[0061] The peeled silkworm cocoons were boiled twice in a Na2CO3 aqueous solution and washed with deionized water to obtain SF, which was then dissolved in a lithium bromide aqueous solution and subjected to centrifugation, filtration, dialysis and concentration treatments (at 4°C) to obtain a 2wt% SF solution;

[0062] (3) Preparation of high-durability fiber-shaped SF-based memristors;

[0063] (3.1) A saturated calomel electrode was used as a reference electrode, a platinum electrode was used as a counter electrode, and Ag fiber a was used as a working electrode. All three electrodes were inserted into a metal ion electrolyte and deposited at a constant potential of -0.5 V for 30 seconds. The electrodes were then ultrasonically treated for 5 seconds and dried to obtain Ag fiber a with metal nanoparticles (SnSe nanoparticles) deposited on the surface (SEM as shown in FIG. Figure 2 As shown), the average particle size of the metal nanoparticles is 20nm, the coverage of the metal nanoparticles on the surface of the Ag fiber a is 20%, and the visible light absorption intensity of the metal nanoparticles is 0.10au (the visible light absorption intensity of the metal nanoparticles on the surface of the Ag fiber a cannot be directly tested, and a set of parallel experiments is required, that is, the Ag fiber a is replaced with ITO transparent glass, and the visible light absorption intensity of the ITO transparent glass is measured before the test, and the visible light absorption intensity of the ITO transparent glass deposited with metal nanoparticles is measured after the experiment, then the visible light absorption intensity of the metal nanoparticles = | visible light absorption intensity of the ITO transparent glass deposited with metal nanoparticles - visible light absorption intensity of the ITO transparent glass |);

[0064] (3.2) The Ag fiber c was connected to the negative electrode of a DC power supply, and the Ag fiber a with metal nanoparticles deposited on the surface was connected to the positive electrode of a DC power supply. Subsequently, the Ag fiber c and the Ag fiber a with metal nanoparticles deposited on the surface were immersed in SF solution in parallel, and a voltage of 0.1 V was applied for deposition for 500 s to obtain the Ag fiber a with metal nanoparticles and SF layer deposited on the surface. After the metal nanoparticles and the SF layer were deposited on the surface in sequence, the radius of the Ag fiber a increased by 28 nm.

[0065] (3.3) By overlapping Ag fiber a with metal nanoparticles and SF layer deposited on the surface with Ag fiber b, a high-durability fibrous SF-based memristor is obtained.

[0066] The high-durability fiber-shaped SF-based memristor finally obtained has an HRS resistance of 26000Ω, an initial SET voltage of 0.21V, an LRS resistance of 125Ω, and an operating current of 10 -7 A, the number of erasable times exceeds 10 3 times; the resistance of the high-durability fiber-shaped SF-based memristor can be maintained for 7500s under HRS and LRS (e.g. Figure 4As shown), the resistance retention times under HRS and LRS after storage for one month are 5800 s and 6000 s respectively (as Figure 5 shown), that is, the reduction rates of the resistance retention times under HRS and LRS after storage for one month do not exceed 23%; the average SET voltage of the highly durable fibrous SF-based memristor in the 1st - 200th cycle is 0.20 V, and the standard deviation is 0.02 V, indicating that the highly durable fibrous SF-based memristor can achieve 200 stable erasing and writing processes.

[0067] Comparative Example 1

[0068] A preparation method of a fibrous bio-memristor, which is only different from Example 1 in that: step (3.1) is not carried out, and in step (3.2), an SF layer is directly deposited on Ag fiber a.

[0069] The HRS resistance value of the finally prepared fibrous bio-memristor is 36000 Ω, the initial value of the SET voltage is 0.15 V, and the LRS resistance value is 12500 Ω; the average SET voltage of the fibrous bio-memristor in the 1st - 100th cycle is 0.22 V, and the standard deviation is 0.1 V.

[0070] Compared with Example 1, the cycling stability of the fibrous bio-memristor in Comparative Example 1 is significantly worse. This is because in Comparative Example 1, metal nanoparticles were not deposited on Ag fiber a, resulting in the formation of conductive filaments requiring a higher voltage during the SET process due to the lack of enhanced electric fields at the metal nanoparticles, and the growth of conductive filaments being random and disordered, making it difficult to form and maintain stably. When a reverse electric field is applied to dissolve the conductive filaments and then a forward electric field is applied again, it is impossible to precisely form stable conductive filaments at the same position, resulting in unstable switching of the resistance state during the cycling of the fibrous bio-memristor, and thus significantly reducing its cycling stability.

[0071] Comparative Example 2

[0072] A preparation method of a fibrous bio-memristor, which is only different from Example 1 in that: step (2) is not carried out, and the specific processes of steps (3.2) - (3.3) are as follows:

[0073] (3.2) Connect Ag fiber c to the negative pole of the DC power supply, connect Ag fiber a with metal nanoparticles deposited on its surface to the positive pole of the DC power supply. Subsequently, immerse Ag fiber c and Ag fiber a with metal nanoparticles deposited on its surface parallelly into an aqueous solution of zinc nitrate with a concentration of 0.004 mol / ml, apply a voltage of -0.8 V at 60 °C for 60 s to deposit, and obtain Ag fiber a with metal nanoparticles and a ZnO layer deposited on its surface. After sequentially depositing metal nanoparticles and an electrodeposited ZnO layer on the surface, the increase in the radius of Ag fiber a is 32 nm;

[0074] Ag fiber a with metal nanoparticles and ZnO layer deposited on its surface is connected to Ag fiber b, and a fibrous bio-memristor is obtained.

[0075] The HRS resistance value of the finally obtained fibrous bio-memristor is 6500 Ω, the initial value of the SET voltage is 2.1 V, and the LRS resistance value is 625 Ω; the average SET voltage of the fibrous bio-memristor in the 1st - 200th cycle is 2.4 V, and the standard deviation is 0.8 V.

[0076] Compared with Example 1, the cycling stability of the fibrous bio-memristor in Comparative Example 2 is significantly worse. This is because in Comparative Example 2, the SF layer is replaced with a ZnO layer. Compared with the SF layer, the lattice structure of the ZnO layer is dense, the ion migration resistance is large, and it does not have a microcrystalline structure like the SF layer. Inside the ZnO layer (i.e., the functional layer), only the local electric field of the metal nanoparticles acts, and the stable growth of the conductive filaments cannot be achieved, resulting in a decrease in cycling stability.

[0077] Comparative Example 3

[0078] A preparation method of a fibrous bio-memristor is basically the same as that of Example 1, except that: the steps of sequentially depositing metal nanoparticles and electro-depositing the SF layer on the surface of Ag fiber a are replaced by the step of coating a dispersion liquid on the surface of Ag fiber a, and the dispersion liquid is composed of an SF solution and metal nanoparticles (the types and sizes are the same as the metal nanoparticles in the fibrous bio-memristor of Example 1).

[0079] The finally obtained fibrous bio-memristor is basically the same as that of Example 1, except that: the metal nanoparticles are uniformly dispersed in the SF layer.

[0080] The resistance retention times of the finally obtained fibrous bio-memristor at HRS and LRS are 5000 s and 5500 s respectively, and the resistance retention times at HRS and LRS after being stored for one month are 1500 s and 1700 s respectively.

[0081] Comparing Example 1 with Comparative Example 3, it can be seen that the durability of the fibrous bio-memristor in Example 1 is significantly higher than that in Comparative Example 3. The fundamental reason is that in Comparative Example 3, metal nanoparticles are directly doped into the SF layer. Although this method can also improve the performance of the memristor, there are many limitations. For example, the metal nanoparticles dispersed on the surface of SF are in contact with air and thus oxidized, and the metal nanoparticles may react with the SF layer to form unexpected phases such as low-conductivity compounds, resulting in a decrease in switching performance; especially for bio-protein materials such as SF, its durability is reduced and the cycle stability declines. In addition, since the doping of SF and metal nanoparticles is a simple physical combination, during repeated operations, the aggregation or migration of metal nanoparticles may lead to the degradation of the SF layer structure and shorten the device life. In Example 1, metal nanoparticles are first deposited on the fiber surface, and then the SF layer is electrodeposited. Depositing metal nanoparticles below the SF layer will not cause the above problems, because the layered structure of metal nanoparticles and SF deposited electrochemically separately is a chemical bond, which can achieve the long-term stable interaction between metal nanoparticles and SF, and the metal nanoparticles are encapsulated by SF and not in contact with air, greatly improving the durability of the device. In addition, due to the action of the local electric field of metal nanoparticles in Example 1, when the SF layer is deposited, the nucleation rate of SF will be accelerated and the internal microcrystal size will be smaller, so as to better cooperate during the operation of the memristor.

[0082] Example 2

[0083] A preparation method of a high-durability fibrous SF-based memristor is as follows:

[0084] (1) Preparation of materials;

[0085] Silkworm cocoons: The origin is Guiyang, Guizhou Province;

[0086] Aqueous Na2CO3 solution: The mass fraction is 0.5 wt%;

[0087] Deionized water;

[0088] Aqueous lithium bromide solution: The concentration is 9.3 mol / L;

[0089] Saturated calomel electrode;

[0090] Platinum sheet electrode;

[0091] Au fibers a, Au fibers b, Au fibers c: All are Au fibers with a diameter of 500 nm;

[0092] Metal ion electrolyte: The pH value is 2.5 (adjusted by an aqueous HCl solution with a concentration of 0.1 M), and it is prepared from an aqueous stannous chloride solution and an aqueous sodium selenite solution with a volume ratio of 1:1. The concentrations of the aqueous stannous chloride solution and the aqueous sodium selenite solution are both 2 mM;

[0093] (2) Prepare the SF solution;

[0094] Boil the peeled silkworm cocoons twice in an aqueous solution of Na2CO3, wash them with deionized water to obtain SF, and then dissolve SF in an aqueous solution of lithium bromide. After centrifugation, filtration, dialysis, and concentration (performed at 4 °C) in sequence, an SF solution with a concentration of 2.3 wt% is obtained;

[0095] (3) Prepare a highly durable fibrous SF-based memristor;

[0096] (3.1) Use a saturated calomel electrode as the reference electrode, a platinum plate electrode as the counter electrode, and Au fiber a as the working electrode. Insert the three electrodes into the metal ion electrolyte solution. After constant potential deposition at a voltage of -0.75 V for 45 s, perform ultrasonic treatment for 6 s and then dry to obtain Au fiber a with metal nanoparticles deposited on its surface. The average particle size of the metal nanoparticles is 25 nm, the coverage rate of the metal nanoparticles on the surface of Au fiber a is 38%, and the visible light absorption intensity of the metal nanoparticles is 0.12 a.u.;

[0097] (3.2) Connect Au fiber c to the negative pole of the DC power supply and connect Au fiber a with metal nanoparticles deposited on its surface to the positive pole of the DC power supply. Subsequently, immerse Au fiber c and Au fiber a with metal nanoparticles deposited on its surface parallelly into the SF solution, apply a voltage of 5 V for deposition for 3000 s to obtain Au fiber a with metal nanoparticles and an SF layer deposited on its surface. After sequentially depositing metal nanoparticles and an electro-deposited SF layer on the surface, the increase value of the radius of Ag fiber a is 42 nm;

[0098] (3.3) Lap Au fiber a with metal nanoparticles and an SF layer deposited on its surface with Au fiber b to obtain a highly durable fibrous SF-based memristor.

[0099] The HRS resistance value of the finally prepared highly durable fibrous SF-based memristor is 12000 Ω, the initial value of the SET voltage is 0.2 V (the voltage-current change curve of the highly durable fibrous SF-based memristor during the first cycle is as Figure 1 shown), the LRS resistance value is 85 Ω, the working current is 10 -4 A, and the erasable and writable times exceed 10 3 times; the resistance retention time of the highly durable fibrous SF-based memristor under HRS and LRS can both reach 7000 s, and the reduction rate of the resistance retention time under HRS and LRS after storing for one month does not exceed 24%; the average SET voltage of the highly durable fibrous SF-based memristor in the 1st - 200th cycle period is 0.18 V, and the standard deviation is 0.03 V.

[0100] Example 3

[0101] A preparation method of a highly durable fibrous SF-based memristor is as follows:

[0102] (1) Preparation of materials;

[0103] Silkworm cocoons: The place of origin is Tongxiang City, Zhejiang Province;

[0104] Aqueous Na2CO3 solution: The mass fraction is 0.5 wt%;

[0105] Deionized water;

[0106] Aqueous lithium bromide solution: The concentration is 9.3 mol / L;

[0107] Saturated calomel electrode;

[0108] Platinum sheet electrode;

[0109] Ag fibers a, Ag fibers b, Ag fibers c: All are Ag fibers with a diameter of 100 μm;

[0110] Metal ion electrolyte solution: The pH value is 2.3 (adjusted by an aqueous HCl solution with a concentration of 0.1 M), and it is prepared from an aqueous stannous chloride solution and an aqueous sodium selenite solution with a volume ratio of 1:1. The concentrations of the aqueous stannous chloride solution and the aqueous sodium selenite solution are both 2 mM;

[0111] (2) Preparation of SF solution;

[0112] The peeled silkworm cocoons are boiled twice in the aqueous Na2CO3 solution, washed with deionized water to obtain SF, and then SF is dissolved in the aqueous lithium bromide solution and successively subjected to centrifugation, filtration, dialysis, and concentration (performed at 4 °C) to obtain an SF solution with a concentration of 2 wt%;

[0113] (3) Preparation of a highly durable fibrous SF-based memristor;

[0114] (3.1) Using the saturated calomel electrode as the reference electrode, the platinum sheet electrode as the counter electrode, and Ag fiber a as the working electrode, insert the three electrodes into the metal ion electrolyte solution. After constant potential deposition at a voltage of -0.75 V for 60 s, perform ultrasonic treatment for 5 s and then dry to obtain Ag fiber a with metal nanoparticles deposited on its surface. The average particle size of the metal nanoparticles is 31 nm, the coverage rate of the metal nanoparticles on the surface of Ag fiber a is 54%, and the visible light absorption intensity of the metal nanoparticles is 0.15 a.u. (The ultraviolet-visible absorption spectrum is as Figure 3 shown);

[0115] (3.2) Connect the Ag fiber c to the negative pole of the DC power supply, and connect the Ag fiber a with metal nanoparticles deposited on its surface to the positive pole of the DC power supply. Subsequently, immerse the Ag fiber c and the Ag fiber a with metal nanoparticles deposited on its surface parallelly into the SF solution, apply a voltage of 1.5 V for 1500 s for deposition, and obtain the Ag fiber a with metal nanoparticles and an SF layer deposited on its surface. After the metal nanoparticles and the electro-deposited SF layer are sequentially deposited on the surface, the increased value of the radius of the Ag fiber a is 31 nm;

[0116] (3.3) Lap the Ag fiber a with metal nanoparticles and an SF layer deposited on its surface with the Ag fiber b, and thus obtain the highly durable fibrous SF-based memristor.

[0117] The HRS resistance value of the finally prepared highly durable fibrous SF-based memristor is 62000 Ω, the initial value of the SET voltage is 0.23 V, the LRS resistance value is 2500 Ω, and the working current is 10 -9 A, and the erasable and writable times exceed 10 3 times; the resistance retention time of the highly durable fibrous SF-based memristor under HRS and LRS can both reach 7500 s, and the reduction rate of the resistance retention time under HRS and LRS after storage for one month does not exceed 23%; the average SET voltage of the highly durable fibrous SF-based memristor in the 1st - 200th cycle period is 0.22 V, and the standard deviation is 0.04 V.

[0118] Example 4

[0119] A preparation method of a highly durable fibrous SF-based memristor, the specific steps are as follows:

[0120] (1) Preparation of materials;

[0121] Silkworm cocoons: The place of origin is Guiyang City, Guizhou Province;

[0122] Aqueous Na2CO3 solution: The mass fraction is 0.5 wt%;

[0123] Deionized water;

[0124] Aqueous lithium bromide solution: The concentration is 9.3 mol / L;

[0125] Saturated calomel electrode;

[0126] Platinum sheet electrode;

[0127] Pt fibers a, Pt fibers b, Pt fibers c: All are Pt fibers with a diameter of 1 μm;

[0128] Metal ion electrolyte: The pH value is 2.2 (adjusted by an aqueous HCl solution with a concentration of 0.1 M), prepared from an aqueous stannous chloride solution and an aqueous sodium selenite solution with a volume ratio of 1:1. The concentrations of both the aqueous stannous chloride solution and the aqueous sodium selenite solution are 2 mM;

[0129] (2) Prepare the SF solution;

[0130] The peeled cocoons are boiled twice in an aqueous Na2CO3 solution, washed with deionized water to obtain SF, and then SF is dissolved in an aqueous lithium bromide solution and successively subjected to centrifugation, filtration, dialysis, and concentration (performed at 4 °C) to obtain an SF solution with a concentration of 2.5 wt%;

[0131] (3) Prepare a highly durable fibrous SF-based memristor;

[0132] (3.1) Using a saturated calomel electrode as the reference electrode, a platinum plate electrode as the counter electrode, and Pt fiber a as the working electrode, insert the three electrodes into the metal ion electrolyte. After potentiostatic deposition at -1 V for 75 s, perform ultrasonic treatment for 8 s and then dry to obtain Pt fiber a with metal nanoparticles deposited on its surface. The average particle size of the metal nanoparticles is 35 nm, the coverage rate of the metal nanoparticles on the surface of Pt fiber a is 62%, and the visible light absorption intensity of the metal nanoparticles is 0.18 a.u.;

[0133] (3.2) Connect Pt fiber c to the negative pole of the DC power supply and connect Pt fiber a with metal nanoparticles deposited on its surface to the positive pole of the DC power supply. Subsequently, immerse Pt fiber c and Pt fiber a with metal nanoparticles deposited on its surface parallelly into the SF solution and apply a voltage of 7.5 V for deposition for 5000 s to obtain Pt fiber a with metal nanoparticles and an SF layer deposited on its surface. After successively depositing metal nanoparticles and an electrodeposited SF layer on the surface, the increase in the radius of Ag fiber a is 73 nm;

[0134] (3.3) Overlap Pt fiber a with metal nanoparticles and an SF layer deposited on its surface with Pt fiber b to obtain a highly durable fibrous SF-based memristor.

[0135] The HRS resistance value of the finally prepared highly durable fibrous SF-based memristor is 32000 Ω, the initial value of the SET voltage is 0.17 V, the LRS resistance value is 1450 Ω, and the working current is 10 -7 A, and the number of erasable and writable times exceeds 10 3For the high-durability fibrous SF-based memristor, the resistance retention time can reach 6500 s both under HRS and LRS, and the reduction rate of the resistance retention time under HRS and LRS after being stored for one month does not exceed 25%; the average SET voltage of the high-durability fibrous SF-based memristor in the 1st - 200th cycle is 0.15 V, and the standard deviation is 0.02 V.

[0136] Example 5

[0137] A preparation method of a high-durability fibrous SF-based memristor is as follows:

[0138] (1) Preparation of materials;

[0139] Silkworm cocoons: The origin is Tongxiang City, Zhejiang Province;

[0140] Aqueous Na2CO3 solution: The mass fraction is 0.5 wt%;

[0141] Deionized water;

[0142] Aqueous lithium bromide solution: The concentration is 9.3 mol / L;

[0143] Saturated calomel electrode;

[0144] Platinum sheet electrode;

[0145] Au fibers a, Au fibers b, Au fibers c: All are Au fibers with a diameter of 1 mm;

[0146] Metal ion electrolyte solution: The concentration is 0.1 mol / mL, the pH value is 2.7 (adjusted by an aqueous HCl solution with a concentration of 0.1 M), the solute is ZnCl2, and the solvent is an aqueous Na2SO3 solution with a concentration of 0.004 mol / mL (prepared by diluting an aqueous Na2SO3 solution with a concentration of 0.2 mol / mL with water);

[0147] (2) Preparation of SF solution;

[0148] Boil the peeled silkworm cocoons twice in the aqueous Na2CO3 solution, wash them with deionized water to obtain SF, and then dissolve SF in the aqueous lithium bromide solution, and successively carry out centrifugation, filtration, dialysis and concentration (at 4 °C) to obtain an SF solution with a concentration of 3 wt%;

[0149] (3) Preparation of the high-durability fibrous SF-based memristor;

[0150] (3.1) Using a saturated calomel electrode as the reference electrode, a platinum sheet electrode as the counter electrode, and Au fiber a as the working electrode, insert the three electrodes into the metal ion electrolyte. After potentiostatic deposition at -1.5 V for 90 s, perform ultrasonic treatment for 10 s and then dry to obtain Au fiber a with metal nanoparticles (ZnS nanoparticles) deposited on its surface. The average particle size of the metal nanoparticles is 40 nm, the coverage rate of the metal nanoparticles on the surface of Au fiber a is 80%, and the visible light absorption intensity of the metal nanoparticles is 0.15 a.u.;

[0151] (3.2) Connect Au fiber c to the negative pole of the DC power supply and connect Au fiber a with metal nanoparticles deposited on its surface to the positive pole of the DC power supply. Subsequently, immerse Au fiber c and Au fiber a with metal nanoparticles deposited on its surface parallelly into the SF solution, apply a voltage of 10 V for deposition for 7500 s to obtain Au fiber a with metal nanoparticles and an SF layer deposited on its surface. After sequentially depositing metal nanoparticles and an electrodeposited SF layer on the surface, the increase value of the radius of Ag fiber a is 95 nm;

[0152] (3.3) Overlap Au fiber a with metal nanoparticles and an SF layer deposited on its surface with Au fiber b to obtain a highly durable fibrous SF-based memristor.

[0153] The HRS resistance value of the finally prepared highly durable fibrous SF-based memristor is 22000 Ω, the initial value of the SET voltage is 0.33 V, the LRS resistance value is 1150 Ω, and the working current is 10 -7 A, and the erasable and writable times exceed 10 3 times; The resistance retention time of the highly durable fibrous SF-based memristor under HRS and LRS can both reach 6500 s, and the reduction rate of the resistance retention time under HRS and LRS after storing for one month does not exceed 20%; The average SET voltage of the highly durable fibrous SF-based memristor in the 1st - 200th cycle is 0.36 V, and the standard deviation is 0.04 V.

Claims

1. A preparation method of a highly durable fibrous SF-based memristor, characterized in that, After successively depositing metal nanoparticles and electro-depositing an SF layer on the surface of the bottom electrode fiber, it is overlapped with the top electrode fiber to obtain a highly durable fibrous SF-based memristor.

2. The preparation method of a highly durable fibrous SF-based memristor according to claim 1, characterized in that The average particle size of the metal nanoparticles is 20 - 40 nm, the coverage rate of the metal nanoparticles on the surface of the bottom electrode fiber is 20 - 80%, and the visible light absorption intensity of the metal nanoparticles is 0.10 - 0.18 a.u.

3. The preparation method of a highly durable fibrous SF-based memristor according to claim 2, characterized in that, The metal nanoparticles are SnSe nanoparticles, ZnS nanoparticles or NiS nanoparticles.

4. The preparation method of a highly durable fibrous SF-based memristor according to claim 1, characterized in that, After successively depositing metal nanoparticles and electro-depositing an SF layer on the surface, the increased value of the radius of the bottom electrode fiber is 28 - 95 nm.

5. The preparation method of a highly durable fibrous SF-based memristor according to claim 1, characterized in that, The diameter of the bottom electrode fiber is 100 nm - 1 mm; the diameter of the top electrode fiber is 100 nm - 1 mm.

6. The preparation method of a highly durable fibrous SF-based memristor according to claim 5, characterized in that, The bottom electrode fiber is an Ag fiber, Pt fiber, Au fiber, Al fiber, Mg fiber or Cu fiber; the top electrode fiber is an Ag fiber, Pt fiber, Au fiber, Al fiber, Mg fiber or Cu fiber.

7. The preparation method of a highly durable fibrous SF-based memristor according to claim 1, characterized in that, The metal nanoparticles are deposited by electro-deposition, the deposition voltage is -0.5~-1.5 V, and the deposition time is 30 - 90 s.

8. The preparation method of a highly durable fibrous SF-based memristor according to claim 1, characterized in that, When electro-depositing the SF layer, an Ag fiber, Pt fiber, Au fiber, Al fiber, Mg fiber or Cu fiber is connected to the negative pole of a DC power supply, the bottom electrode fiber after depositing the metal nanoparticles is connected to the positive pole of the DC power supply, the two fibers are immersed in the SF solution in parallel, and a voltage of 0.1 - 10 V is applied for 500 - 7500 s for deposition.

9. A high-durability fibrous SF-based memristor, characterized in that, Prepared by using the preparation method of a highly durable fibrous SF-based memristor according to any one of claims 1-8; the HRS resistance value of the highly durable fibrous SF-based memristor is 12,000-62,000 Ω, the initial value of the SET voltage is 0.15-0.33 V, the LRS resistance value is 85-2,500 Ω, and the working current is 10 -9 -10 -4 A, and the erasable and writable times exceed 10 3 times; the resistance retention time of the highly durable fibrous SF-based memristor under HRS and LRS can both reach 6,500-7,500 s, and the reduction rate of the resistance retention time under HRS and LRS after storing for one month does not exceed 25%; the average SET voltage of the highly durable fibrous SF-based memristor in the 1st-200th cycle period is 0.15-0.36 V, and the standard deviation is 0.02-0.04 V.

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