Hydrogen bond organic framework-polyvinyl alcohol composite hydrogel-based synaptic device as well as preparation method and application thereof

Abstract

The invention discloses a hydrogen bond organic framework-polyvinyl alcohol composite hydrogel-based synaptic device as well as a preparation method and application thereof. The synaptic device comprises a zinc electrode on the upper layer, a titanium electrode on the lower layer and double-layer hydrogel clamped between the zinc electrode and the titanium electrode, the double-layer hydrogel comprises negative HOF / PVA composite hydrogel close to the zinc electrode and positive HOF / PVA composite hydrogel close to the titanium electrode, and the negative HOF / PVA composite hydrogel is in contact with the positive HOF / PVA composite hydrogel; the negative electricity HOF is a hydrogen bond organic framework material synthesized by using 1, 2, 4, 5-tetra (4-carboxyphenyl) benzene as a precursor, and the positive electricity HOF is a hydrogen bond organic framework material synthesized by using 1, 3, 6, 8-tetra (p-aminophenyl)-pyrene as a precursor. The core synaptic plasticity performance such as pulse promotion, pulse suppression, long-time-history promotion, long-time-history suppression and pulse time sequence dependent plasticity can be stably shown.

Description

Technical Field

[0001] This invention relates to a hydrogen-bonded organic framework-polyvinyl alcohol composite hydrogel-based synaptic device, its preparation method, and its application, belonging to the fields of ion diodes and biomimetic synapse technology. Background Technology

[0002] Currently, memristors based on the resistive switching effect are the mainstream technology for realizing artificial synapses, among which electrochemical metallization (ECM) memristors stand out. These devices utilize metal cations (such as Zn)... 2+ Electrochemical deposition / dissolution under an applied electric field forms conductive filaments, thereby modulating the device's conductivity. Its ion regulation mechanism is highly compatible with biological synapses, making it a research hotspot. However, ECM memristors generally face the critical challenge of uncontrollable metal dendrite growth: random dendrite growth leads to significant fluctuations in device switching parameters and decreased cycle stability, even causing short-circuit failure in severe cases. Simultaneously, for relatively simple solid-state or gel electrolyte ECM devices, ion migration paths lack effective regulation. While learning (conductivity enhancement) processes can be achieved, forgetting (conductivity reduction) processes largely rely on spontaneous ion diffusion or passive dendrite dissolution, making active, precise, and stable regulation difficult. This deficiency greatly limits the device's application effectiveness and reliability in simulating complex adaptive learning behaviors.

[0003] To address these issues, existing research has explored two main approaches: first, designing specialized hydrogel electrolytes to improve interfacial stability or inhibit dendrite growth; and second, constructing heterogeneous ionogel structures to simulate more complex synaptic functions. However, these approaches have significant limitations: the former focuses solely on dendrite suppression to improve cycle life, without addressing the dynamic regulation of learning and forgetting at the synaptic core; the latter, while capable of simulating single synaptic behavior, relies solely on ion relaxation effects, failing to fully utilize dendrite dynamics or combine them with programmable ion migration regulation. Ultimately, it cannot achieve coordinated and proactive management of learning and forgetting dynamics, and it is even more difficult to extend to logical applications of ion diode characteristics. Therefore, breakthroughs in the existing technological framework are still needed. Summary of the Invention

[0004] To address the problems existing in the prior art, this invention provides a hydrogen-bonded organic framework-polyvinyl alcohol composite hydrogel-based synaptic device, its preparation method, and its application.

[0005] To achieve the above objectives, the present invention employs a hydrogen-bonded organic framework-polyvinyl alcohol composite hydrogel-based synaptic device, comprising an upper zinc electrode, a lower titanium electrode, and a double-layer hydrogel sandwiched between the zinc electrode and the titanium electrode.

[0006] The bilayer hydrogel includes a negatively charged HOF / PVA composite hydrogel near the zinc electrode and a positively charged HOF / PVA composite hydrogel near the titanium electrode, and the negatively charged HOF / PVA composite hydrogel is in contact with the positively charged HOF / PVA composite hydrogel.

[0007] The negatively charged HOF is a hydrogen-bonded organic framework material synthesized using 1,2,4,5-tetra(4-carboxyphenyl)benzene as a precursor, and the positively charged HOF is a hydrogen-bonded organic framework material synthesized using 1,3,6,8-tetra-(p-aminophenyl)pyrene as a precursor.

[0008] As an improvement, the positively charged HOF / PVA composite hydrogel is a solid composite hydrogel formed by HOF-PyTTA and PVA.

[0009] As an improvement, the negatively charged HOF / PVA composite hydrogel is a solid composite hydrogel formed by HOF-H4TCPB and PVA.

[0010] As an improvement, the thickness of both the positively charged HOF / PVA composite hydrogel and the negatively charged HOF / PVA composite hydrogel is 2.5-7.5 mm, and the two composite hydrogels are arranged in a fully contact overlapping manner, with a total thickness of 5-15 mm after overlapping.

[0011] A second aspect of the present invention also provides a method for preparing the hydrogen-bonded organic framework-polyvinyl alcohol composite hydrogel-based synaptic device, comprising the following steps:

[0012] (1) Electrode preparation: Zinc and titanium electrodes were prepared by cutting and cutting.

[0013] (2) Preparation of positively charged HOF / PVA composite hydrogel: The positively charged HOF / PVA aqueous solution was dropped into a fixed mold. After the drop was completed, it was placed in a refrigerator for freezing, and then thawed at room temperature. The freeze-thaw process was repeated.

[0014] (3) Preparation of bilayer hydrogel: The negatively charged HOF / PVA aqueous solution is dropped onto the surface of the positively charged HOF / PVA composite hydrogel obtained in step (2). After the drop is completed, it is placed in a refrigerator for freezing, and then thawed at room temperature. The freeze-thaw process is repeated.

[0015] (4) Hydrogel activation: Immerse the bilayer hydrogel obtained in step (3) in zinc sulfate solution;

[0016] (5) Device assembly: After absorbing excess moisture from the surface of the hydrogel activated in step (4), the zinc electrode, double-layer hydrogel, and titanium electrode are fixed with insulating tape to obtain the synaptic device.

[0017] As an improvement, the preparation process of the positively charged HOF / PVA aqueous solution in step (2) is as follows: HOF-PyTTA solution with a concentration of 2-5 mg / ml and PVA solution with a mass fraction of 10% are mixed at a mass ratio of 1:(0.5-2.0) and stirred evenly;

[0018] The preparation steps of the HOF-PyTTA solution are as follows: 1,3,6,8-tetra-(p-aminophenyl)-pyrene is dissolved in N,N-dimethylformamide, sonicated until clear, then dispersed in deionized water and stirred, filtered to obtain a solid membrane, and redispersed in deionized water to obtain the HOF-PyTTA solution.

[0019] As an improvement, the preparation process of the negatively charged HOF / PVA aqueous solution in step (3) is as follows: HOF-H4TCPB solution with a concentration of 2-5 mg / ml and PVA solution with a mass fraction of 10% are mixed at a mass ratio of 1:(0.5-2.0) and stirred evenly;

[0020] The preparation steps of the HOF-H4TCPB solution are as follows: 1,2,4,5-tetra(4-carboxyphenyl)benzene is dissolved in DMF, sonicated until clear, then dispersed in deionized water and stirred, filtered to obtain a solid membrane, and redispersed in deionized water to obtain the HOF-H4TCPB solution.

[0021] As an improvement, the preparation process of the PVA solution is as follows: polyvinyl alcohol-1799 particles are mixed with deionized water and stirred in a water bath at 90-100℃ for 2-5 hours.

[0022] As an improvement, the freezing temperature in steps (2) and (3) is -10 to -20°C, the freezing time is 10-12 hours, the thawing temperature at room temperature is 20-25°C, the thawing time is 10-12 hours, and the number of freeze-thaw cycles is 3-5 times.

[0023] A third aspect of the present invention also provides the application of the hydrogen-bonded organic framework-polyvinyl alcohol composite hydrogel-based synaptic device, or the hydrogen-bonded organic framework-polyvinyl alcohol composite hydrogel-based synaptic device prepared by the preparation method, in biomimetic synaptic devices or as ion diodes.

[0024] The mechanism of this invention is:

[0025] Negatively charged HOF / PVA composite hydrogels and positively charged HOF / PVA composite hydrogels were stacked sequentially, and then pre-cut zinc and titanium electrodes were fixed to the outside with insulating tape to construct a layered synaptic device of Zn-HOF-H4TCPB / PVA-HOF-PyTTA / PVA-Ti. The difference in standard potentials between the zinc and titanium electrodes in the device results in an inherent potential difference even without an applied voltage, which is the basis for the device's initial electrical state. When a positive voltage is applied (zinc electrode positive, titanium electrode negative), Zn... 2+ Under the influence of an electric field, it migrates towards the titanium electrode and is reduced (Zn). 2+ + 2e - →Zn) forms zinc dendrites that deposit on the surface of the titanium electrode, and the zinc electrode surface undergoes an oxidation reaction to form Zn. 2+ Replenishing functional layer ions maintains charge balance. As zinc dendrites continue to deposit, the conductive pathway between the two electrodes gradually improves, the equivalent resistance decreases, the potential difference decreases accordingly, and the device conductivity remains at a high level. When the applied voltage is stopped or a reverse voltage is applied, the zinc dendrites on the titanium electrode surface dissolve (Zn→Zn). 2+ + 2e - The potential difference between the two electrodes increases, and the conductivity decreases. This causes the current to increase or decrease with the number of pulses when the device receives continuous pulses, thus achieving a biomimetic memory effect. Furthermore, the two HOF functional layers in the middle layer of the device have opposite charges: HOF-H4TCPB is negatively charged due to the ionization of the carboxyl group (-COOH), and HOF-PyTTA is positively charged due to the protonation of the amino group (-NH2). When Zn 2+ (Positively charged) transfers between functional layers are affected by the electrical properties of the HOF: In the HOF-PyTTA / PVA layer, the positively charged HOF affects Zn. 2+ Generates repulsive force, slowing down Zn 2+ Migration rate; after entering the HOF-H4TCPB / PVA layer, the negatively charged HOF affects Zn. 2+ Generates attraction, accelerates Zn 2+ Migration rate. This difference in migration rate causes Zn to migrate at different polarities when different voltages are applied. 2+ The migration efficiency varies, and this method can control the zinc dendrite deposition effect on the titanium electrode, making the growth of zinc dendrites on the titanium electrode more controllable, avoiding problems such as zinc dendrite fracture and dissolution due to excessive growth, and enhancing the synaptic plasticity of the device.

[0026] Compared with the prior art, the beneficial effects of the present invention are:

[0027] 1. By relying on the inherent potential difference between the zinc electrode and the titanium electrode, the growth / dissolution of zinc dendrites on the surface of the titanium electrode is regulated by applying voltage, thereby dynamically changing the potential difference and conductivity between the two electrodes, and finally realizing the biomimetic synaptic function. It can stably exhibit core synaptic plasticity properties such as pulse promotion (PPF), pulse suppression (PPD), long duration promotion (LTP), long duration suppression (LTD), and pulse timing-dependent plasticity (STDP).

[0028] 2. Breaking through traditional understanding, the phenomenon of Zn dendrite growth and dissolution, conventionally regarded as a performance defect, is transformed into a core mechanism for dynamic and continuous modulation of synaptic weights. Simultaneously, by designing a hydrogel heterostructure composed of positively charged HOF-PyTTA / PVA and negatively charged HOF-H4TCPB / PVA, the ion-selectivity of HOF is utilized to regulate Zn. 2+ The transmission rate can simulate the long-term memory-forgetting curve of biological synapses after different stimuli from multiple dimensions such as pulse amplitude, pulse number, and pulse frequency, significantly improving the biomimicry of the function.

[0029] 3. It has multi-functional application value: It can be used as a biomimetic synapse device to support neuromorphic computing, and it can also be used as an ion diode based on the unidirectional ion transport characteristics to further build simple logic gate circuits such as AND gates and OR gates; In addition, the core materials of the device, HOF and PVA, have good biocompatibility and degradability, which meet the requirements of environmental friendliness and provide a new technical paradigm for building an artificial synapse system with high biorealism and self-adaptive ability. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the synaptic device according to Embodiment 1 of the present invention;

[0031] Figure 2 The images are scanning electron microscope (SEM) images of the HOF-H4TCPB and HOF-PyTTA films prepared in Example 1 of this invention; in the images, (a) and (b) are HOF-H4TCPB films, and (c) and (d) are HOF-PyTTA films.

[0032] Figure 3 These are scanning electron microscope images of the two HOF / PVA composite hydrogel films prepared in Example 1 of this invention;

[0033] Figure 4 The EPSC and IPSC characteristic curves of the synaptic device of the present invention are shown below.

[0034] Figure 5 The PPF and PPD characteristic curves of the synaptic device of the present invention are shown below.

[0035] Figure 6 The LTP and LTD characteristic curves of the synaptic device of the present invention are shown.

[0036] Figure 7 The SRDP characteristic curves of the synaptic device of the present invention are shown, which are response characteristic curves for different pulse widths and different pulse frequencies; in the figure, (a) represents different pulse widths and (b) represents different pulse frequencies.

[0037] Figure 8 The figure shows the forgetting characteristic curves of the synaptic device of the present invention when the same pulse amplitude is applied but different pulse numbers are applied; in the figure, (a) is the current-time curve generated by the device when 10, 20, 30, 40 and 50 pulses are applied; (b) is a schematic diagram of the current value returning to the initial level when the last two pulses are applied for each pulse number.

[0038] Figure 9 The figure shows the forgetting characteristic curves of the synaptic device of the present invention when different pulse amplitudes are applied, but with the same number of pulses; in the figure, (a) is the current-time curve generated by the device when +2V, +3V, +4V, +5V and +6V voltage pulse amplitudes are applied; (b) is a schematic diagram of the current value returning to the initial level when the last two pulses applied for each voltage amplitude pulse return to the initial level.

[0039] Figure 10 The figure shows the ion diode characteristics of the synaptic device of the present invention; in the figure, (a) is the typical current-voltage characteristic curve of the device when a voltage from -4V to 4V is applied, and (b) is the current response curve of the device under ±3V square wave bias at 0.1Hz.

[0040] Figure 11 The figure shows the construction and testing of the synaptic device of the present invention in AND gate logic circuit; in the figure, (a) is a schematic diagram of the AND gate circuit construction; (b) is the test curve of the actual output voltage when the AND gate circuit is applied with states 00, 01, 10 and 11 respectively.

[0041] Figure 12 The figure shows the construction and testing of the synaptic device of the present invention in an OR gate logic circuit; in the figure, (a) is a schematic diagram of the OR gate circuit construction; (b) is the actual voltage test curve of the output when the OR gate circuit is applied to the states of 00, 01, 10 and 11 respectively. Detailed Implementation

[0042] The following embodiments are further illustrations of the present invention and serve as explanations of the technical content of the present invention. However, the essence of the present invention is not limited to the embodiments described below. Those skilled in the art can and should know that any simple changes or substitutions based on the spirit of the present invention should fall within the protection scope claimed by the present invention.

[0043] Example 1

[0044] A method for preparing a hydrogen-bonded organic framework-polyvinyl alcohol composite hydrogel-based synaptic device includes the following steps:

[0045] (1) Electrode preparation: Cut zinc foil and titanium sheet to make electrode sheets of 1.5cm×1.5cm; Zinc foil pretreatment: sandpaper to remove surface oxide layer, ultrasonically cleaned with acetone, ethanol and deionized water for 15min each, and then dried in a vacuum drying oven at 35℃ for 30min to obtain zinc electrode and titanium electrode.

[0046] (2) Preparation of HOF suspension

[0047] Take 0.1 mmol of negatively charged HOF precursor (1,2,4,5-tetra(4-carboxyphenyl)benzene, H4TCPB) and 0.1 mmol of positively charged HOF precursor (1,3,6,8-tetra-(p-aminophenyl)pyrene, PyTTA), dissolve them separately in 7.5 ml of N,N-dimethylformamide (DMF), and sonicate for 15 min until the solid is completely dissolved to form a clear solution;

[0048] The two solutions were dispersed in 162 ml of deionized water and stirred at room temperature for 2 h to obtain a uniform HOF colloidal suspension. The suspension was centrifuged at 8000 rpm for 10 min, the precipitate was collected, washed with deionized water and centrifuged 3 times, and the precipitate was transferred to a vacuum filter to prepare a uniform HOF film.

[0049] The two types of films were dispersed in deionized water to prepare HOF suspensions with a concentration of 2 mg / ml (corresponding to negatively charged HOF-H4TCPB suspension and positively charged HOF-PyTTA suspension).

[0050] (3) Preparation of PVA solution: Weigh 5g of polyvinyl alcohol-1799 type granules, add them to a beaker containing 45ml of deionized water, seal the mouth of the beaker and place it in a 95℃ water bath and stir for 2h until the granules are completely dissolved to obtain a clear and transparent 10wt% PVA solution.

[0051] (4) Preparation of positive and negative charged HOF / PVA solutions

[0052] Negatively charged HOF / PVA solution: Mix 2 mg / ml HOF-H4TCPB suspension with 10 wt% PVA solution at a mass ratio of 1:0.5 and stir for 1 hour until homogeneous;

[0053] Positively charged HOF / PVA solution: Mix 2 mg / ml HOF-PyTTA suspension with 10 wt% PVA solution at a mass ratio of 1:0.5 and stir for 1 hour until homogeneous;

[0054] (5) Preparation of monolayer HOF / PVA composite hydrogel: Take 0.5 ml of the positively charged HOF / PVA solution from step (4), drop it into a 1.5 cm × 1.5 cm plastic mold, freeze at -10℃ for 12 h, thaw at room temperature (20-25℃) for 12 h, repeat the freeze-thaw cycle 3 times to obtain a structurally stable positively charged HOF / PVA composite hydrogel;

[0055] (6) Preparation of bilayer HOF / PVA composite hydrogel: Take 0.5 ml of the negatively charged HOF / PVA solution from step (4) and drop it onto the surface of the positively charged HOF / PVA composite hydrogel from step (5). Repeat the freezing-thawing process of step (5) (freeze at -10℃ for 12 h, thaw at room temperature for 12 h, freeze and thaw 3 times) to obtain bilayer hydrogel, ensuring that the positive and negative layers are in close contact without falling off.

[0056] (7) Synaptic device assembly: The synaptic device is stacked in the following order: zinc electrode, negatively charged HOF / PVA composite hydrogel, positively charged HOF / PVA composite hydrogel, and titanium electrode. The thickness of both the positively charged and negatively charged HOF / PVA composite hydrogels is 5 mm. The two layers of composite hydrogels are overlapped in full contact, with a total overlap thickness of 10 mm. Finally, 3-5 turns of 0.5-1 cm wide insulating tape are used to secure the device, ensuring structural stability. Figure 1 The synaptic device shown.

[0057] The HOF-H4TCPB and HOF-PyTTA films prepared in Example 1 were characterized by scanning electron microscopy (SEM), and the results are as follows: Figure 2 Figures 2(a) and 2(b) show that a single HOF-H4TCPB is a sheet-like structure, and a dense HOF-H4TCPB film is formed by stacking. Figures 2(c) and 2(d) show that a single HOF-PyTTA is a rod-like structure, and a HOF-PyTTA film is formed by stacking.

[0058] Meanwhile, the HOF-H4TCPB / PVA composite hydrogel film and the HOF-PyTTA / PVA composite hydrogel film were characterized by SEM, and the results are as follows: Figure 3 As shown in the figure. Analysis shows that both rod-shaped HOF-PyTTA and sheet-shaped HOF-H4TCPB can be uniformly encapsulated by the PVA matrix, forming a compact structure of HOF functional unit-PVA matrix. This significantly enhances the mechanical strength and structural stability of HOF materials, effectively solving the defects of pure HOF materials being brittle and easily broken, and providing structural support for device assembly and long-term use.

[0059] Example 2

[0060] Based on Example 1, only one variable was changed, and the rest of the steps were completely consistent with Example 1. The specific variable is as follows: the concentration of HOF-H4TCPB suspension and HOF-PyTTA suspension in step (2) was adjusted from 2 mg / ml to 3 mg / ml.

[0061] Example 3

[0062] Based on Example 1, only one variable was changed, and the rest of the steps were completely consistent with Example 1. The specific variable is as follows: the concentration of HOF-H4TCPB suspension and HOF-PyTTA suspension in step (2) was adjusted from 2 mg / ml to 4 mg / ml.

[0063] Example 4

[0064] Based on Example 1, only one variable was changed, and the rest of the steps were completely consistent with Example 1. The specific variable is as follows: the concentration of HOF-H4TCPB suspension and HOF-PyTTA suspension in step (2) was adjusted from 2 mg / ml to 5 mg / ml.

[0065] Example 5

[0066] Based on Example 1, only one variable is changed, and the rest of the steps are completely consistent with Example 1. The specific variable is as follows: the mass ratio of HOF-H4TCPB to PVA and the mass ratio of HOF-PyTTA to PVA in step (4) are adjusted from 1:0.5 to 1:1.

[0067] Example 6

[0068] Based on Example 1, only one variable is changed, and the rest of the steps are completely consistent with Example 1. The specific variable is as follows: the mass ratio of HOF-H4TCPB to PVA and the mass ratio of HOF-PyTTA to PVA in step (4) are adjusted from 1:0.5 to 1:1.5.

[0069] Example 7

[0070] Based on Example 1, only one variable is changed, and the rest of the steps are completely consistent with Example 1. The specific variable is as follows: the mass ratio of HOF-H4TCPB to PVA and the mass ratio of HOF-PyTTA to PVA in step (4) are adjusted from 1:0.5 to 1:2.

[0071] Example 8

[0072] The synaptic device of the present invention has significant biomimetic synaptic plasticity, and can realize functions such as excitatory postsynaptic current (EPSC), inhibitory postsynaptic current (IPSC), pulse promotion (PPF), pulse suppression (PPD), long duration promotion (LTP), long duration suppression (LTD), and pulse timing-dependent plasticity (STDP). The test results are shown in Figures 4-7 respectively; the response characteristics of the device to different pulse parameters are shown in Figures 8-10.

[0073] Test method: Using the Autolab electrochemical workstation from Metrohm, Switzerland, electrical signals with set high level, low level and number of cycle pulses were applied to the device, and the response current output was tested.

[0074] Figure 4 This indicates that the device exhibits significant differences in current response to pulse stimulation of different polarities: the current response triggered by a positive pulse simulates the excitatory postsynaptic current (EPSC) of a biological synapse, while the reverse pulse simulates the inhibitory postsynaptic current (IPSC), achieving precise biomimicry of the excitation-inhibition dual-state function of a biological synapse.

[0075] Figure 5 This indicates that when two pairs of consecutive positive or negative pulses are applied, the device exhibits pulse promotion (PPF) and pulse suppression (PPD) characteristics: the peak response current of the second pulse is higher than that of the first (PPF) or lower than that of the first (PPD), which is consistent with the dynamic response law of biological synapses under short-term stimulation, reflecting the short-term memory simulation capability of the device.

[0076] Figure 6 This indicates that under multiple pairs of continuous positive or negative pulse stimulation, the device exhibits long-term promotion (LTP) and long-term inhibition (LTD) effects: after a large number of pulses, the peak value of the response current remains higher than (LTP) or lower than (LTD) initial value, and the current does not immediately return to zero during the low-level phase, but shows a slow changing trend, simulating the formation and decay process of biological synaptic long-term memory.

[0077] Figure 7 This indicates that the pulse parameters regulate the device's conductivity: when pulses of different high-level pulse widths or frequencies are applied, the degree of conductivity change in the low-level phase increases significantly with increasing pulse width and frequency. This suggests that the device can achieve fine modulation of synaptic weights by adjusting the stimulation parameters, which is consistent with the adaptive characteristics of biological synapses to stimulation intensity.

[0078] Figure 8 and Figure 9The memory retention characteristics of the device were further verified: the more pulse stimuli there were and the higher the amplitude, the longer the "forgetting" time of the device (i.e. the longer the memory retention). This rule is highly consistent with the memory mechanism of the human brain: repeated or strong stimulation will strengthen the neural synaptic connection, making the memory more stable, and the memory can still be retained for a long time even if the stimulation disappears.

[0079] Example 9

[0080] The synaptic device of the present invention has stable ion diode characteristics, enabling precise switching logic control and demonstrating clear application value in logic circuit construction.

[0081] Taking the device obtained in Example 1 as an example: Figure 10 (a) shows the characteristic curve of the ion diode in the voltage range of -4V to 4V. The results show that when the applied voltage does not reach the turn-on threshold, the device only generates a weak leakage current (in the off state); when the voltage exceeds the turn-on threshold, the current increases by orders of magnitude (enters the turn-on state). Figure 10 (b) shows the diode current response curves of the device at -3V and 3V levels. For each cycle, the forward and reverse bias currents rapidly decrease from the initial high value to a constant value, indicating that the switching characteristics remain stable in multiple cycle tests, verifying the reliability of the device's diode logic function.

[0082] Furthermore, the AND and OR gate circuits built using this device (test results are shown in Figures 11 and 12) show that the actual output logic waveforms are in complete agreement with the theoretical design, fully demonstrating that the device of this invention can be directly used to build basic logic circuits, thus expanding its application scenarios in the field of information processing.

[0083] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions or improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A hydrogen-bonded organic framework-polyvinyl alcohol composite hydrogel-based synaptic device, characterized in that, It includes an upper zinc electrode, a lower titanium electrode, and a double-layer hydrogel sandwiched between the zinc electrode and the titanium electrode; The bilayer hydrogel includes a negatively charged HOF / PVA composite hydrogel near the zinc electrode and a positively charged HOF / PVA composite hydrogel near the titanium electrode, and the negatively charged HOF / PVA composite hydrogel is in contact with the positively charged HOF / PVA composite hydrogel. The negatively charged HOF is a hydrogen-bonded organic framework material synthesized using 1,2,4,5-tetra(4-carboxyphenyl)benzene as a precursor, and the positively charged HOF is a hydrogen-bonded organic framework material synthesized using 1,3,6,8-tetra-(p-aminophenyl)pyrene as a precursor.

2. The hydrogen-bonded organic framework-polyvinyl alcohol composite hydrogel-based synaptic device according to claim 1, characterized in that, The positively charged HOF / PVA composite hydrogel is a solid composite hydrogel formed by HOF-PyTTA and PVA.

3. The hydrogen-bonded organic framework-polyvinyl alcohol composite hydrogel-based synaptic device according to claim 1, characterized in that, The negatively charged HOF / PVA composite hydrogel is a solid composite hydrogel formed by HOF-H4TCPB and PVA.

4. The hydrogen-bonded organic framework-polyvinyl alcohol composite hydrogel-based synaptic device according to claim 1, characterized in that, The thickness of both the positively charged HOF / PVA composite hydrogel and the negatively charged HOF / PVA composite hydrogel is 2.5-7.5 mm. The two composite hydrogels are arranged in a fully contact overlapping manner, and the total thickness after overlapping is 5-15 mm.

5. The method for preparing the hydrogen-bonded organic framework-polyvinyl alcohol composite hydrogel-based synaptic device according to any one of claims 1-4, characterized in that, Includes the following steps: (1) Electrode preparation: Zinc and titanium electrodes were prepared by cutting and cutting. (2) Preparation of positively charged HOF / PVA composite hydrogel: The positively charged HOF / PVA aqueous solution was dropped into a fixed mold. After the drop was completed, it was placed in a refrigerator for freezing, and then thawed at room temperature. The freeze-thaw process was repeated. (3) Preparation of bilayer hydrogel: The negatively charged HOF / PVA aqueous solution is dropped onto the surface of the positively charged HOF / PVA composite hydrogel obtained in step (2). After the drop is completed, it is placed in a refrigerator for freezing, and then thawed at room temperature. The freeze-thaw process is repeated. (4) Hydrogel activation: Immerse the bilayer hydrogel obtained in step (3) in zinc sulfate solution; (5) Device assembly: After absorbing excess moisture from the surface of the hydrogel activated in step (4), the zinc electrode, double-layer hydrogel, and titanium electrode are fixed with insulating tape to obtain the synaptic device.

6. The method for preparing the hydrogen-bonded organic framework-polyvinyl alcohol composite hydrogel-based synaptic device according to claim 5, characterized in that, The preparation process of the positively charged HOF / PVA aqueous solution in step (2) is as follows: HOF-PyTTA solution with a concentration of 2-5 mg / ml and PVA solution with a mass fraction of 10% are mixed at a mass ratio of 1:(0.5-2.0) and stirred evenly; The preparation steps of the HOF-PyTTA solution are as follows: 1,3,6,8-tetra-(p-aminophenyl)-pyrene is dissolved in N,N-dimethylformamide, sonicated until clear, then dispersed in deionized water and stirred, filtered to obtain a solid membrane, and redispersed in deionized water to obtain the HOF-PyTTA solution.

7. The method for preparing the hydrogen-bonded organic framework-polyvinyl alcohol composite hydrogel-based synaptic device according to claim 6, characterized in that, The preparation process of the negatively charged HOF / PVA aqueous solution in step (3) is as follows: HOF-H4TCPB solution with a concentration of 2-5 mg / ml and PVA solution with a mass fraction of 10% are mixed at a mass ratio of 1:(0.5-2.0) and stirred evenly; The preparation steps of the HOF-H4TCPB solution are as follows: 1,2,4,5-tetra(4-carboxyphenyl)benzene is dissolved in DMF, sonicated until clear, then dispersed in deionized water and stirred, filtered to obtain a solid membrane, and redispersed in deionized water to obtain the HOF-H4TCPB solution.

8. The method for preparing the hydrogen-bonded organic framework-polyvinyl alcohol composite hydrogel-based synaptic device according to claim 7, characterized in that, The preparation process of the PVA solution is as follows: Polyvinyl alcohol-1799 particles are mixed with deionized water and stirred in a water bath at 90-100℃ for 2-5 hours.

9. The method for preparing the hydrogen-bonded organic framework-polyvinyl alcohol composite hydrogel-based synaptic device according to claim 5, characterized in that, The freezing temperature in steps (2) and (3) is -10 to -20°C, the freezing time is 10-12 hours, the thawing temperature at room temperature is 20-25°C, the thawing time is 10-12 hours, and the number of freeze-thaw cycles is 3-5 times.

10. A hydrogen-bonded organic framework-polyvinyl alcohol composite hydrogel-based synaptic device according to any one of claims 1-4, or a hydrogen-bonded organic framework-polyvinyl alcohol composite hydrogel-based synaptic device prepared by the preparation method according to any one of claims 5-9, for use in biomimetic synaptic devices or as an ion diode.

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