Interdigital supercapacitor, construction method and application

Abstract

The invention discloses a construction method of a high-stability interdigital supercapacitor, and the method comprises the steps: firstly designing the interdigital supercapacitor, and obtaining an interdigital conductive substrate through micromachining; then synthesizing a conductive organic frame nano material with good conductivity, and combining with a conductive polymer PEDOT: PSS to construct a composite flexible nano frame composite layer; by optimizing modification conditions, the composite material is modified on an interdigital conductive substrate, and a novel interdigital supercapacitor is prepared. The result shows that the constructed interdigital supercapacitor still keeps high specific capacitance and high stability after tens of thousands of charging and discharging cycles under different current densities. Based on the high-stability interdigital supercapacitor, a platform for promoting the neural stem cells to differentiate into neurons based on in-situ electrical stimulation is subsequently established in the method: electrical stimulation is continuously and stably applied through the interdigital supercapacitor, so that the differentiation speed of the neural stem cells is remarkably increased; and an effective research tool is provided for research of a basic molecular mechanism of neurodegenerative diseases.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of electrochemical biosensing, and relates to a interdigital supercapacitor, a construction method and application. BACKGROUND

[0002] Bioelectric signals can communicate with bioelectronic devices to influence cell function and drive growth. Most bioelectronic work has focused on measuring electrically excitable cells such as neurons and cardiomyocytes. Modern bioelectronics has a multi-scale structure and is widely used in drug delivery, biosensing and biological regulation. It has great therapeutic potential in treating many biological diseases including Parkinson's disease, congenital heart defects and paralysis.

[0003] For neural stem cell (NSC)-based therapies, the key to success is to effectively and rapidly differentiate NSCs into functional neurons. Electrical stimulation is one of the most effective and widely used ways to promote neural differentiation and enhance neurogenesis by activating voltage-gated ion channels. For example, deep brain electrical stimulation (DBS) is characterized by minimal trauma, reversibility and adjustability by implanting electrodes into specific targets in the brain and continuously or intermittently transmitting current from implanted batteries.

[0004] Many bioelectronic devices have been designed, such as supercapacitors. Microdevices using multi-scale porous material structures and interdigitated microelectrode layouts can regulate cardiomyocytes (CMs) in vitro under physiological conditions, excite ex vivo heart and retina tissues in vitro, and stimulate sciatic nerves in vivo. Such studies show that such designs have practical value in future bioelectric therapy. The current challenges of this technology include improving the stability of the device and developing more customized and adaptive stimulation.

[0005] As a supercapacitor device that provides bioelectric stimulation, long-term stability is very important. However, many electrode materials have problems such as structural collapse, volume expansion, and destruction of the original molecular chain structure during continuous cycling, which leads to performance degradation and poor stability. SUMMARY

[0006] In order to solve the problems existing in the prior art, the purpose of the present application is to provide a interdigital supercapacitor, a construction method and an application. The present application first proposes an interdigital supercapacitor, successfully makes an interdigital conductive substrate through a microprocessing method; secondly synthesizes a nanomaterial MOF / COF and introduces a conductive polymer poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonic acid) (PEDOT:PSS) with high mechanical properties and biocompatibility; finally optimizes the modification conditions of the nanomaterial MOF / COF and the conductive polymer, and modifies them on the interdigital conductive substrate as a mixed electrode material, and successfully constructs an interdigital supercapacitor. The present application uses the nanomaterial MOF / COF and PEDOT:PSS as the electrode material of the supercapacitor, and after pretreatment, the nanomaterial MOF / COF and PEDOT:PSS provide effective stimulation for neural stem cells and promote the rapid differentiation of the neural stem cells by adjusting the frequency, voltage and time of the stimulation.

[0007] The interdigital supercapacitor has high stability and adjustable stimulation mode. After pretreatment, the insulating part PSS in the conductive polymer (PEDOT:PSS) falls off and dissolves in water, the proportion of PEDOT increases, and the conductive performance is enhanced. Part of PEDOT and the aromatic structure in the nanomaterial MOF / COF have π-π interaction, further enhancing the stability. The interdigital supercapacitor still maintains high specific capacitance and high stability after tens of thousands of charge-discharge cycles, and provides stable and controllable electrical stimulation for promoting the differentiation of neural stem cells.

[0008] The present application provides an interdigital supercapacitor, which is constructed by an interdigital conductive substrate, a conductive polymer PEDOT:PSS and a nanomaterial MOF / COF, has the typical characteristics of a double-layer supercapacitor, can perform ion adsorption and desorption under a voltage window of -0.1-0.6V, and realizes cyclic charge-discharge. The specific capacitance of the interdigital supercapacitor can reach 5.1F g -1 Under different current densities (1000, 500 and 300 μA cm -2 ), the specific capacitance is maintained at 96.9%, 95.6% and 95.3% respectively after 10,000 cycles, and has high stability.

[0009] The present application further provides a construction method of an interdigital supercapacitor, which comprises the following specific steps:

[0010] Step (1): design an interdigital supercapacitor, determine the size of the interdigital conductive substrate of the interdigital supercapacitor and the width of a single substrate strip and the gap between the substrate strips;

[0011] Step (2): make an interdigital conductive substrate through microprocessing;

[0012] Step (3): Modify the interdigitated conductive substrate with nanomaterials MOF / COF and poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonic acid) to prepare the interdigitated supercapacitor.

[0013] Step (4): The interdigitated supercapacitor obtained in step (3) is pretreated by electrochemical method (cycled 1000 times at a voltage of -0.1 to 0.6V) to obtain an interdigitated supercapacitor with stable performance and cyclic charging and discharging capability.

[0014] In step (1), the simplified design diagram of the interdigitated supercapacitor is as follows: Figure 2 As shown.

[0015] In step (1), the interdigitated conductive substrate is composed of two independent interdigitated electrodes with an overall diameter of 14 mm.

[0016] In step (1), the width of the single substrate strip is 5 μm.

[0017] In step (1), the gap between the substrate strips is 5 μm.

[0018] In step (2), the microfabrication steps of the interdigitated conductive substrate include: fabrication of a mask, cleaning, spin coating, pre-baking, photolithography, post-baking, development, oxidation, gold plating, chemical stripping, and silver paste curing.

[0019] The mask is manufactured according to the design of the interdigitated supercapacitor in step (1).

[0020] The cleaning process involves using acetone, isopropanol, anhydrous ethanol, water, and ultrasound.

[0021] The photoresist used in the spin coating process is a negative photoresist, applied at 2000-4000 revolutions, with a thickness of 1-2 μm; preferably, it is applied at 3000 revolutions with a thickness of 2 μm.

[0022] The pre-baking temperature is 100-120℃ and the duration is 1-3 minutes; preferably, the pre-baking temperature is 115℃ and the duration is 2 minutes.

[0023] The photolithography dose is 50-100 mJ / cm². 2 Preferably, it is 100 mJ / cm. 2 .

[0024] The post-baking temperature is 100-120℃ and the duration is 1-3 minutes; preferably, the post-baking temperature is 115℃ and the duration is 1 minute.

[0025] The developing reagents include MIF 300, AZ 400K, DPD 230, etc.; preferably, MIF 300.

[0026] The oxygenation process is wherein the pressure is 1-2 Pa, the power is 100-200 W, the O2 flow rate is 50-100 sccm, and the time is 1-2 minutes; preferably, the pressure is 1 Pa, the power is 150 W, the O2 flow rate is 80 sccm, and the time is 1 minute.

[0027] The gold-plated film is deposited using EB (electron beam) vapor deposition with a beam current of 2-5 A / s; preferably, it is 4 A / s.

[0028] The chemical stripping process uses a stripping solution, which includes acetone, hydrogen peroxide, dimethyl sulfoxide, etc.; preferably, it is acetone.

[0029] The silver paste is cured at a temperature of 150-200℃ for 10-20 minutes; preferably, the silver paste is cured at a temperature of 200℃ for 15 minutes.

[0030] In step (3), the preparation method of the nanomaterial MOF / COF includes the following steps:

[0031] Step 1: Mix the desired metal compound and its corresponding ligand in concentrated ammonia water, stir and react to obtain a black mixture;

[0032] Step 2: The mixture obtained in Step 1 is processed by steps such as filtration, washing, and drying to obtain the nanomaterial MOF / COF.

[0033] In step 1, the metal compound is selected from one or more of nickel chloride hexahydrate, copper acetate, cobalt acetate tetrahydrate, etc.; preferably, it is nickel chloride hexahydrate.

[0034] In step 1, the ligand is selected from one or more of 2,3,6,7,10,11-hexaaminobenzophenanthrene hexahydrochloride, 2,3,6,7,10,11-hexahydroxytribenzophenanthrene, 5,10,15,20-tetra(4-aminophenyl)porphyrin, etc.; preferably, it is 2,3,6,7,10,11-hexaaminobenzophenanthrene hexahydrochloride;

[0035] In step 1, the molar ratio of the metal compound to the ligand is (2-5):(1-2); the amount of concentrated ammonia added is 5-10 mL; the reaction temperature is 60-80℃; the reaction time is 12-24 hours; preferably, the molar ratio of the metal compound to the ligand is 1.5:1; the amount of concentrated ammonia added is 5 mL; the reaction temperature is 80℃; and the reaction time is 24 hours.

[0036] In step 2, the filtration time is 5-10 minutes, and the pressure is 1-2 bar; the washing solvent is 150-200 mL of water and 150-200 mL of ethanol, the washing is performed 3-5 times, and the washing time is 3-5 minutes per wash; the drying conditions are: drying in a vacuum oven for 12-24 hours, and drying temperature is 49-60℃; preferably, the filtration time is 5 minutes, and the pressure is 1 bar; the washing solvent is 180 mL of water and 180 mL of ethanol, the washing is performed 3 times, and the washing time is 5 minutes per wash; the drying conditions are: drying in a vacuum oven for 24 hours, and drying temperature is 49℃.

[0037] In step 2, the nanomaterial MOF / COF includes Ni-MOF black powder, Cu-MOF black powder, Cu-COF dark purple powder, or Co-COF dark purple powder, etc.

[0038] In one specific embodiment, the preparation method of the nanomaterial MOF / COF includes the following steps (taking Ni-MOF as an example):

[0039] Step (1): Nickel chloride hexahydrate and 2,3,6,7,10,11-hexaaminobenzophenanthrene hexahydrochloride solution were mixed in concentrated ammonia water and stirred to react, yielding a black mixture. The reaction process is shown in reaction formula (A):

[0040]

[0041] Step (2): The mixture obtained in step 1 is processed by steps such as filtration, washing, and drying to obtain Ni-MOF black powder.

[0042] In step (1), the molar ratio of nickel chloride hexahydrate and 2,3,6,7,10,11-hexaaminobenzophenanthrene hexahydrochloride is 1.5:1, and the solid powder is dissolved in 140 mL of ultrapure water;

[0043] In step (1), the amount of concentrated ammonia added is 5-10 mL;

[0044] In step (1), the reaction temperature is 60-80℃;

[0045] In step (1), the reaction time is 12-24 hours.

[0046] The water used to prepare the solution is ultrapure water.

[0047] In step (2), the filtration process takes 5-10 minutes.

[0048] In step (2), the filtration pressure is 1-2 bar;

[0049] In step (2), the solvent used for washing is 150-200mL of water and 150-200mL of ethanol, the number of washings is 3-5 times, and the washing time is 3-5min / time.

[0050] In step (2), the drying conditions are: drying temperature of 49-60℃ in a vacuum oven and drying time of 12-24 hours.

[0051] The washing water is ultrapure water.

[0052] The present invention also provides a nanomaterial MOF / COF prepared by the above method.

[0053] Before modifying the interdigitated conductive substrate with the nanomaterial MOF / COF and poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonic acid), this invention further includes co-modifying and optimizing the nanomaterial MOF / COF and poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonic acid). The optimization method includes the following specific steps:

[0054] The suspension of the nanomaterial MOF / COF and the poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonic acid) were sequentially modified onto a glassy carbon electrode by drop casting, according to a volume ratio of (1-5):(1-5) and the modification order of first modifying the nanomaterial MOF / COF or poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonic acid). Then, electrochemical performance tests were performed using an electrochemical workstation connected to the electrode, wherein the reference electrode was an Ag / AgCl electrode and the auxiliary electrode was a platinum wire electrode. The best electrochemical performance test result was considered as the optimal condition.

[0055] The glassy carbon electrode mentioned above in this invention is independent of the interdigitated conductive substrate. Since the availability of interdigitated conductive substrates makes simultaneous multi-condition modification for optimization impossible and the modification process is cumbersome, this invention uses a glassy carbon electrode for optimization modification experiments. The optimal conditions in this invention are determined by calculating the specific capacitance, which is directly related to the modification ratio and order.

[0056] Specifically, the optimization method further includes:

[0057] Step A: Prepare a suspension of the aforementioned MOF / COF nanomaterials at a certain concentration, the structures of which are shown in Formulas B-E respectively:

[0058]

[0059] Step B: The suspension of the nanomaterial MOF / COF and the PEDOT:PSS from Step A are sequentially modified onto the glassy carbon electrode by drop casting according to different volume ratios and / or modification order.

[0060] Step C: Using a three-electrode system containing a reference electrode, the modified glassy carbon electrode from step B is immersed in PBS solution at room temperature. The electrode is connected using an electrochemical workstation, and cyclic voltammetry is set to obtain the scanning curve.

[0061] Step D: Calculate the specific capacitance under different modification conditions based on the cyclic voltammetry curves. The condition with the highest specific capacitance is considered the optimal condition.

[0062] In step A, the concentration of the MOF / COF nanomaterial suspension is 1-2 mg / mL. -1 Preferably, the concentration is 2 mg / mL. -1 .

[0063] In step A, the PEDOT:PSS aqueous solution has a mass concentration of 1-2%; preferably, the PEDOT:PSS aqueous solution has a mass concentration of 1.4%.

[0064] In step B, the volume ratio is (1-5):(1-5), preferably 1:4; the modification order is MOF on the bottom layer or PEDOT:PSS on the bottom layer, preferably PEDOT:PSS on the bottom layer.

[0065] In step C, the reference electrode is an Ag / AgCl electrode, the auxiliary electrode is a platinum wire electrode, and the working electrode is a glassy carbon electrode.

[0066] In step C, the concentration of PBS is 10-20 mM, preferably 10 mM.

[0067] In step C, the potential range of the cyclic voltammetry is -0.2 to 0.8V, preferably -0.1 to 0.6V.

[0068] In step C, the scanning speed is 10-100 mV / s; preferably, it is 50 mV / s.

[0069] In step D, the calculation formula is shown in equation (F):

[0070]

[0071] This invention also provides a method for modifying the nanomaterial MOF / COF prepared by the optimized method and the optimized product of poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonic acid) as a composite electrode material (the specific modification steps are: first, poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonic acid) is drop-cast onto the surface of an interdigitated conductive substrate, and after natural drying, the nanomaterial MOF / COF suspension is drop-cast onto the top layer in a ratio of (1-5):(1-5), and then dried to complete the process). This method constructs a highly stable interdigitated supercapacitor on the interdigitated conductive substrate.

[0072] The method for achieving high stability described in this invention involves modifying the aforementioned nanomaterials MOF / COF and PEDOT:PSS on the electrode surface under optimized conditions and performing electrochemical pretreatment for a period of time. This process significantly increases the specific capacitance, which gradually stabilizes. Analysis using SEM, Raman, XPS, and AFM revealed that after pretreatment, the boundary between the two nanomaterials, MOF / COF and PEDOT:PSS, gradually blurred, exhibiting a tendency to merge. The resonant structural transformation of the PEDOT thiophene backbone and the π-π interactions between the aromatic structures in PEDOT:PSS and the MOF / COF nanomaterials form a stable structure. The reduced proportion of the insulating PSS portion in PEDOT:PSS improves the overall conductivity of the material and increases the conductive pathway area. This results in a hybrid electrode material with high specific capacitance and high stability.

[0073] The present invention also provides an interdigitated supercapacitor prepared by the above-described construction method.

[0074] The present invention also provides the construction method as described above, or the application of the interdigitated supercapacitor as described above in promoting the rapid differentiation of neural stem cells into neurons and astrocytes by electrical stimulation.

[0075] In this invention, the specific steps for promoting rapid differentiation of neural stem cells through electrical stimulation are as follows:

[0076] Step i: Isolate neural stem cells (NSCs) from the forebrain of C57 BL / 6 mouse embryos and provide them with complete culture medium for normal growth.

[0077] Step ii: After UV sterilization, the interdigitated supercapacitor is placed at the bottom of a confocal culture dish as a culture medium substrate. Mouse laminin is coated onto the surface of both the ordinary culture dish and the interdigitated supercapacitor, and incubated in a constant temperature incubator at 37°C for 1 hour. Then, the plates are washed three times or more with PBS.

[0078] Step iii: Inoculate NSCs onto ordinary culture dishes and interdigitated supercapacitors respectively, and incubate them overnight in a constant temperature incubator at 37°C to allow them to adhere.

[0079] Step iv: Replace the complete culture medium with neuronal differentiation culture medium.

[0080] Step v: Apply electrical stimulation to the NSCs grown on the interdigital supercapacitors using a function generator.

[0081] Step vi: Immunofluorescence staining was performed on NSCs grown on ordinary culture dishes and interdigitated supercapacitors, and the differentiation of NSCs was observed by fluorescence microscopy.

[0082] In step i, the complete culture medium consists of Neurobasal medium, 2% B-27, 1% penicillin / streptomycin (P / S), and basic fibroblast growth factor (bFGF, 20 ng / mL). -1 ) and epidermal growth factor (EGF, 20 ng / mL) -1 ).

[0083] In step ii, the concentration of laminin is 1-10 μg / cm³. 2 Preferably, it is 5 μg / cm³. 2 .

[0084] In step ii, the concentration of PBS is 10-20 mM, preferably 10 mM.

[0085] In step iv, the neuronal differentiation medium consists of Neurobasal medium, 2% B-27, and 1% penicillin / streptomycin (P / S).

[0086] In step v, the applied electrical stimulation is a sine wave.

[0087] In step v, the frequency of the sine wave is 1-200Hz, preferably 50Hz.

[0088] In step v, the amplitude of the sine wave is 0-0.4V, preferably 0.05V.

[0089] In step v, the duration of the electrical stimulation is 10-30 minutes per day for 1-7 days, preferably 20 minutes for 5 days.

[0090] In step vi, immunofluorescence staining is performed on the cell nucleus, Tuj1 (a marker of early neuronal differentiation), and GFAP (astrocytes), respectively.

[0091] The Neurobasal medium has an osmotic pressure of 224 mOsm / Kg and a pH of 7.11.

[0092] The beneficial effects of this invention include: First, it proposes an interdigitated supercapacitor, which is obtained by microfabrication of an interdigitated conductive substrate; then, it synthesizes an organic framework nanomaterial (MOF / COF) with good conductivity and introduces a conductive polymer (PEDOT:PSS) with high mechanical properties and biocompatibility; finally, it optimizes the modification conditions of both materials and co-modifies them on the interdigitated conductive substrate, followed by electrochemical pretreatment at a voltage of -0.1 to 0.6 V to obtain a highly stable interdigitated supercapacitor. The interdigitated supercapacitor constructed based on this invention can be used to promote the rapid differentiation of neural stem cells through electrical stimulation. Attached Figure Description

[0093] Figure 1 Schematic diagram of neural stem cell differentiation stimulated by interdigital supercapacitors.

[0094] Figure 2 (A) Design drawing of interdigitated supercapacitor; (B) Partial SEM image of interdigitated supercapacitor.

[0095] Figure 3 (A) SEM (Scanning Electron Microscopy) image of Ni-MOF; (B) XRD (X-ray Diffraction) image of Ni-MOF; (C) XPS (X-ray Photoelectron Spectroscopy) image of Ni-MOF: peak fitting diagram of Ni and N.

[0096] Figure 4 (A) Selection of voltage window; (B) Optimization of modification ratio of nanomaterials MOF / COF and PEDOT:PSS; (C) Comparison of specific capacitance under different modification ratios; (D) Selection of modification order of nanomaterials MOF / COF and PEDOT:PSS (a is based on nanomaterials MOF / COF, b is based on PEDOT:PSS); (E) Charge-discharge curves of interdigitated supercapacitors modified according to optimized conditions under different constant currents in a three-electrode system; (F) EIS (electrochemical impedance spectroscopy) spectrum of interdigitated supercapacitors.

[0097] Figure 5 Current densities of 300, 500, and 1000 μA / cm² were respectively. -2 The cyclic stability diagram of the supercapacitor.

[0098] Figure 6(A)(B) SEM images of electrode materials before and after pretreatment; (C) a. Comparison of Raman peaks before and after PEDOT:PSS cycling; b. Local magnified image of Raman peaks; (D) XPS images of electrode materials before and after pretreatment. a, b. Peak fitting diagrams of O and S elements before cycling; c, d. Peak fitting diagrams of O and S elements after cycling; (E) AFM (Atomic Force Microscopy) images of different electrode materials: a. Nanomaterial MOF / COF; b. PEDOT:PSS; c. Direct mixing of nanomaterial MOF / COF and PEDOT:PSS solution; d. Mixed electrode material after pretreatment with nanomaterial MOF / COF and PEDOT:PSS modified on the electrode according to optimized conditions.

[0099] Figure 7 (A) Fluorescent image of NSCs grown normally on a regular culture dish after immunostaining; (B) Fluorescent image of NSCs after immunostaining five days after electrical stimulation by an interdigital supercapacitor. Detailed Implementation

[0100] The invention will be further described in detail below with reference to the specific embodiments and accompanying drawings. Except for the contents specifically mentioned below, the processes, conditions, and experimental methods for implementing the invention are all common knowledge and general knowledge in the art, and the invention does not have any particular limitations.

[0101] Example 1: Design and substrate fabrication of interdigitated supercapacitors

[0102] Design and substrate fabrication of interdigitated supercapacitors. First, design the drawings for the interdigitated supercapacitor, determining the overall dimensions, the width of individual strips, and the spacing between the strips. For example... Figure 2 As shown, the diameter of the interdigitated supercapacitor is 14 mm, the width of a single strip is 5 μm, and the gap between the strips is 5 μm.

[0103] The microfabrication steps include mask fabrication, cleaning, photoresist coating, pre-baking, photolithography, post-baking, development, oxidation, gold plating, chemical stripping, and silver paste curing. (1) Fabricate the mask according to the design drawings. (2) Cleaning. Clean with acetone + isoacetone + anhydrous ethanol + water and perform ultrasonic treatment. The purpose of this step is to clean surface impurities to facilitate subsequent processes. (3) Coat the sapphire surface with photoresist evenly. Use negative photoresist during photoresist coating, set the rotation speed to 3000 rpm, and the final thickness to 1-2 μm. (4) Initially cure and shape the photoresist to facilitate subsequent exposure. The pre-baking temperature is 115℃ and the duration is 2 minutes. (5) Photolithography. Transfer the interdigitated electrode pattern to the substrate by ultraviolet light exposure. The dose used is 100 mJ / cm. 2(6) The exposed photoresist is further baked at 115°C for 1 minute. (7) Development. High-purity organic alkaline developer AZ 300MIF is used to chemically treat the exposed photoresist to reveal the pattern. (8) Oxygenation: Plasma cleaning. Pressure is 1 Pa, power is 150 W, O2 flow rate is 80 sccm, and time is 1 minute. Oxygenation before metal plating is to remove residual photoresist so that the metal can adhere better to the substrate. (9) Film deposition. Gold film is deposited on the substrate by electron beam evaporation at a beam current of 4 A / s and a gold film thickness of 150 nm. (10) Chemical stripping. Excess metal patterns, especially on the photoresist, are removed by etching with stripping solution, leaving only the metal patterns on the interdigitated supercapacitor. (11) Silver paste curing. Conductive silver paste needs to be cured by heating to form a good electrical connection. The curing temperature is 200°C and the time is 15 minutes.

[0104] Example 2:

[0105] Preparation of conductive nanomaterials (Ni-MOF): 323 mg (1.36 mmol) of nickel chloride hexahydrate (NiCl2·6H2O) and 487 mg (0.91 mmol) of 2,3,6,7,10,11-hexaaminobenzophenanthrene hexahydrochloride (HATP·6HCl) were dissolved in small amounts of water, and then added sequentially to 140 mL of water. Then, 5 mL of concentrated ammonia solution (NH4OH, 14 mol / L) was added. -1 The product was added to the mixture. The mixture in the flask was stirred in an oil bath at 80°C for 24 hours, and then allowed to cool. A black powder was obtained by centrifugation, then washed with water (180 mL) and ethanol (180 mL), dried under a nitrogen stream, and stored in a nitrogen-filled glove box until use. Finally, the product was dried in a vacuum oven at 49°C and 84.6 kPa for 24 hours.

[0106] Figure 3 A is a SEM image of Ni-MOF, which has a sheet-like stacked structure. Figure 3 B is the XRD pattern of Ni-MOF. The spectrum shows significant peaks at 2θ = 4.7°, 9.5° and 12.6°, indicating long-range order in the ab plane. Figure 3 C is the peak fitting of Ni and N in the XPS of Ni-MOF, proving that Ni-MOF was successfully synthesized.

[0107] Example 3:

[0108] Optimization of modification conditions for nanomaterials MOF / COF and PEDOT:PSS: First, a suspension of nanomaterials MOF / COF (Ni-MOF) prepared in Example 2 of this invention at a certain concentration was prepared, and commercially available PEDOT:PSS (1.4%, PEDOT:PSS≈1:2.5) was purchased. The nanomaterials MOF / COF (Ni-MOF) and PEDOT:PSS were sequentially modified onto a glassy carbon electrode using a drop casting method at different volume ratios, such as 1:1, 2:1, 3:1, 4:1, 5:1, etc., and / or modification order. Then, using a three-electrode system containing a reference electrode, the glassy carbon electrode was immersed in PBS solution at room temperature. An electrochemical workstation was used to connect the electrodes, and cyclic voltammetry was set to obtain scanning curves. The reference electrode was an Ag / AgCl electrode, the auxiliary electrode was a platinum wire electrode, and the working electrode was a glassy carbon electrode. The electrolyte was PBS with a concentration of 10 mM. The potential range was -0.1 to 0.6 V, and the scan rate was 50 mV / s. Finally, the specific capacitance under different modification conditions was calculated based on the cyclic voltammetry curves.

[0109] Figure 4 A shows the CV curves of the supercapacitor at different voltage windows, obtained by selecting the operating voltage window using cyclic voltammetry. An oxygen peak may appear below -0.1V, while a sharp peak begins to appear above 0.6V. To maintain good double-layer performance, a voltage window of -0.1 to 0.6V is selected. Figure 4 B represents the CV curves of the supercapacitor under different modification ratios. Figure 4 C represents the calculated specific capacitance under different modification ratios. The specific capacitance reaches its maximum when the modification ratio is 1:4. Figure 4 D represents the choice of modification order, and a and b are the CV curves for modifying the nanomaterial MOF / COF (Ni-MOF) first and PEDOT:PSS first, respectively. Calculations of the specific capacitance show that PEDOT:PSS modification first results in better electrochemical performance. Figure 4 E represents the charge-discharge curves of the electrode modified according to the optimized conditions under different constant currents. As shown in the figure, the curves all exhibit an approximately triangular shape, indicating that they possess the characteristics of a double-layer capacitor. Figure 4 F is the electron transfer resistance (EIS) of the supercapacitor, which is approximately 100Ω.

[0110] Figure 5 The stability of the electrode modified according to the optimized conditions under different current densities is demonstrated by maintaining a high specific capacitance after 10,000 cycles.

[0111] Example 4:

[0112] The method for obtaining high stability described in this invention involves preparing the nanomaterials MOF / COF (Ni-MOF) and PEDOT:PSS prepared in Example 2 of this invention under optimized conditions (preparing 2 mg / mL of the nanomaterials). -1 A MOF / COF nanomaterial suspension with a mass concentration of 1.4% PEDOT:PSS (MOF / COF:PEDOT:PSS = 1:4, PEDOT:PSS at the bottom layer) was applied to the electrode surface. After electrochemical pretreatment for a period of time, the specific capacitance significantly increased and gradually stabilized. Analysis using SEM, Raman, XPS, and AFM revealed that after pretreatment, the boundary between the MOF / COF (Ni-MOF) and PEDOT:PSS layers gradually blurred, showing a tendency to merge. The resonant structural transformation of the PEDOT thiophene backbone and the π-π interactions of the aromatic structures in PEDOT:PSS and MOF formed a stable structure. The reduced proportion of the insulating PSS in PEDOT:PSS improved the overall conductivity of the material and increased the conductive pathway area. This resulted in a hybrid electrode material with high specific capacitance and high stability.

[0113] Figure 6 A and 6B are SEM images of the modified electrode before and after cycling, respectively. Before cycling, the boundaries between the nanomaterials MOF / COF and PEDOT:PSS are clear, while after cycling, the two gradually merge together. Figure 6 C represents the Raman peak of the electrode material before and after cycling, at 1400–1500 cm⁻¹. -1 The point is the stretching vibration of Cα=Cβ on the PEDOT pentagonal ring. After cycling, the Raman peak of PEDOT:PSS shifts to higher wavenumbers, which can be attributed to the stretching of the Cα=Cβ thiophene ring, the resonant structural transformation of the thiophene backbone, and the π-π interactions of aromatic structures in PEDOT:PSS and MOF. Figure 6 D represents the XPS of the electrode material before and after cycling. After cycling, the molar ratio of O to S attributable to PEDOT increases, indicating that PEDOT separates from PSS after cycling. Some PSS is dissolved and lost, and the proportion of PEDOT increases, thus enhancing conductivity. Figure 6 E represents the AFM of the following materials: MOF / COF (Ni-MOF), PEDOT:PSS, a direct mixture of MOF / COF (Ni-MOF) and PEDOT:PSS solutions, and a mixed electrode material after pretreatment with MOF / COF (Ni-MOF) and PEDOT:PSS modified onto the electrode under optimized conditions. After cycling, the material roughness increases, the structure becomes more ordered, and the conductive pathways increase.

[0114] Example 5:

[0115] The method for promoting rapid differentiation of neural stem cells by electrical stimulation as described in this invention first involves isolating neural stem cells (NSCs) from the forebrain of C57 BL / 6 mouse embryos, providing appropriate complete culture medium for normal growth, and regularly changing the culture medium and performing cell passages. Interdigitated supercapacitors modified and pretreated according to optimized conditions are sterilized under UV light and placed at the bottom of a confocal culture dish as the culture medium substrate. Then, mouse laminin (density 5 μg / cm³) is coated onto the surfaces of both ordinary culture dishes and the interdigitated supercapacitors. 2 After incubation at 37°C, the cells were washed three times or more with PBS in a clean bench. NSCs were then seeded at specific cell densities onto both ordinary culture dishes and interdigitated supercapacitors, and incubated overnight at 37°C to allow adhesion. Microscopic observation showed that most cells adhered and grew normally on both substrates. The complete culture medium was then replaced with a neuron differentiation medium without growth factors.

[0116] NSCs in ordinary culture dishes were placed in a 37°C incubator to allow for normal differentiation. NSCs cultured on an interdigitated supercapacitor substrate were removed from the incubator at fixed times each day and subjected to electrical stimulation using a function generator. The applied electrical stimulation was a sine wave with a frequency of 50 Hz and an amplitude of 0.05 V, lasting 20 minutes daily for five days. After five days, the nuclei, Tuj1, and GFAP of NSCs under both culture conditions were immunofluorescently stained, and their differentiation was observed under a fluorescence microscope.

[0117] like Figure 7 As shown in Figure A, normally cultured NSCs showed low differentiation, low Tuj1 content, and no obvious synapses or axons. Figure 7 In sample B, the differentiation degree of NSCs after electrical stimulation was significantly increased, with high Tuj1 content and distinct neuronal morphology. This indicates that the provided electrical stimulation can promote rapid differentiation of NSCs.

[0118] The scope of protection of this invention is not limited to the above embodiments. Any variations and advantages that can be conceived by those skilled in the art without departing from the spirit and scope of the inventive concept are included in this invention and are protected by the appended claims.

Claims

1. An interdigital supercapacitor, characterized by, The interdigital supercapacitor is jointly constructed by an interdigital conductive substrate, poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonic acid) (PEDOT:PSS) and nanomaterial MOF / COF, has typical characteristics of double-layer supercapacitors, and can realize ion adsorption and desorption and cyclic charging and discharging under certain conditions.

2. The interdigital supercapacitor of claim 1, wherein, The specific capacitance of the interdigital supercapacitor reaches 5.1 F g -1 At 1000, 500 and 300 μA cm -2 The specific capacitance is maintained at 96.9%, 95.6% and 95.3% respectively after 10,000 cycles.

3. A method of constructing an interdigitated supercapacitor, characterized by, The construction method comprises the following specific steps: Step (1): designing an interdigital supercapacitor, determining the size of the interdigital conductive substrate of the interdigital supercapacitor and the width of a single substrate strip and the gap between the substrate strips; Step (2): fabricating the interdigital conductive substrate through microprocessing; Step (3): modifying the nanomaterial MOF / COF and poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonic acid) on the interdigital conductive substrate to prepare the interdigital supercapacitor.

4. The construction method of claim 3, wherein, In the step (1), the interdigital conductive substrate is composed of two independent interdigital electrodes, and the overall diameter is 14 mm; the width of a single substrate strip and the gap between the substrate strips are both 5 μm; And / or, in the step (2), the microprocessing step of the interdigital conductive substrate comprises the following steps: fabricating a mask mask plate, cleaning, uniform gluing, pre-baking, photolithography, post-baking, development, oxygen punching, gold plating film, chemical stripping and silver glue curing; And / or, in the step (3), the preparation method of the nanomaterial MOF / COF comprises the following steps: Step 1: mixing a metal compound and a corresponding ligand in concentrated ammonia water, stirring and reacting to obtain a corresponding mixture; Step 2: treating the mixture obtained in the step 1 through filtration, washing and drying steps to obtain the nanomaterial MOF / COF.

5. The construction method of claim 4, wherein, In the step 1, the molar ratio of the metal compound to the ligand is (2-5):(1-2); and / or, the metal compound is selected from one or more of nickel chloride hexahydrate, copper acetate and cobalt acetate tetrahydrate; and / or, the ligand is selected from one or more of 2,3,6,7,10,11-hexaaminobenzenophenyl hexahydrochloride, 2,3,6,7,10,11-hexahydrotriphenylbenzophenyl and 5,10,15,20-tetra(4-aminophenyl)porphyrin; and / or, the addition amount of the concentrated ammonia water is 5-10 mL; and / or, the reaction temperature is 60-80℃; and / or, the reaction time is 12-24 hours; And / or, in the step 2, the filtration time is 5-10 minutes, and the pressure is 1-2 bar; and / or, the solvent used for washing is 150-200 mL of water and 150-200 mL of ethanol, the washing times are 3-5 times, and the washing time is 3-5 min / time; and / or, the drying condition is that the drying time in a vacuum oven is 12-24 h, and the drying temperature is 49-60℃.

6. The construction method of claim 3, wherein, The modification of the nanomaterial MOF / COF and poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonic acid) before the interdigital conductive substrate further comprises optimization of the modification of the nanomaterial MOF / COF and poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonic acid), and the method for optimization comprises the following specific steps: The suspension of the nanomaterial MOF / COF and the poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonic acid) are modified on a glassy carbon electrode by drop casting in a volume ratio of (1-5):(1-5) and in a modification order of first modifying the nanomaterial MOF / COF or the poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonic acid); then electrochemical performance testing is performed, and an electrochemical workstation is used to connect the electrode, wherein the reference electrode is an Ag / AgCl electrode, the auxiliary electrode is a platinum wire electrode, and the working electrode is a glassy carbon electrode; finally, the best electrochemical performance testing result is considered as the optimal condition; The concentration of the suspension of the nanomaterial is 1.0-2.0 mg mL -1 The poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonic acid) is a 1-2% aqueous solution.

7. The construction method of claim 6, wherein, The optimized product of the nanomaterial MOF / COF and the poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonic acid) prepared by the method for optimization is used as a composite electrode material to modify the interdigital conductive substrate, and the interdigital supercapacitor is constructed; wherein the modification steps are as follows: the poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonic acid) is first drop cast on the surface of the interdigital conductive substrate, and then the suspension of the nanomaterial MOF / COF is drop cast on the uppermost layer in a ratio of (1-5):(1-5) after natural drying, and the modification is completed after drying.

8. The construction method of claim 3, wherein, Step (4) is further included: the interdigital supercapacitor obtained in step (3) is pretreated by an electrochemical method: 1000 cycles at a voltage of-0.1-0.6 V, to obtain an interdigital supercapacitor with stable performance and cyclic charge-discharge performance.

9. The interdigital supercapacitor prepared by the construction method of any one of claims 3-8.

10. Use of the interdigital supercapacitor of any one of claims 1, 2, and 9 in promoting differentiation of neural stem cells into neurons and astrocytes under electrical stimulation.

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