Preparation method of conductive film used as cerebral cortex patch, conductive film and application of conductive film

Abstract

The invention discloses a preparation method of a conductive film used as a cerebral cortex patch, the conductive film and application of the conductive film, and the preparation method comprises the following steps: mixing PVDF polyvinylidene fluoride powder and ionic liquid, dispersing the mixture in a solvent, and heating and stirring in a water bath to prepare a mixed solution; and introducing the mixed solution into a polytetrafluoroethylene mold, drying, cooling to room temperature, and removing from the mold to obtain the conductive film. According to the invention, high-temperature-resistant and hydrophobic commercial ionic liquid is used as a conductive medium, so that the problems that common conductive hydrogel is easy to decompose at high temperature and high voltage, easy to leak and the like are solved; the mass fraction of the ionic liquid and the conductivity form a linear relationship, and the ionic liquid with the doping amount lower than 50% is difficult to realize high conductivity; meanwhile, the conflict between transparency and conductivity of an electronic conductor is solved through ionic conductivity, and high conductivity (the conductivity is 10 <-3 > S / cm <-1 >) and high transparency (the light transmittance is 75%) are achieved.

Description

Technical Field

[0001] The present invention belongs to the field of medical material preparation, and particularly relates to a preparation method of a conductive film used as a cerebral cortex patch, the conductive film and its application. Background Art

[0002] Currently, the metal films used for EEG patches are often rigid materials, and their high Young's modulus often brings inevitable damage to brain tissues and causes strong immune responses. The use of metals limits their application in high-spatial-resolution imaging (magnetoencephalography, positron emission tomography, functional magnetic resonance imaging, functional near-infrared spectroscopy, etc.).

[0003] Currently, flexible materials for brain patches are usually composed of conductive polymers, but their electron conjugation structure as the conductive basis makes it difficult for them to have transparent properties.

[0004] Meanwhile, in conductive polymers, the conflict between electron conductivity and transparency makes it difficult to complete the excitation and collection of light while recording electrical signals. Summary of the Invention

[0005] The purpose of this part is to outline some aspects of the embodiments of the present invention and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this part, the abstract of the specification and the title of the invention of this application to avoid obscuring the purpose of this part, the abstract of the specification and the title of the invention, and such simplifications or omissions cannot be used to limit the scope of the present invention.

[0006] In view of the above and / or problems existing in the prior art, the present invention is proposed.

[0007] Therefore, the purpose of the present invention is to overcome the deficiencies in the prior art and provide a preparation method of a conductive film used as a cerebral cortex patch.

[0008] To solve the above technical problems, the present invention provides the following technical solution: A preparation method of a conductive film used as a cerebral cortex patch, including,

[0009] Mixing PVDF (polyvinylidene fluoride) powder and an ionic liquid and dispersing them in a solvent, heating and stirring in a water bath to obtain a mixed solution;

[0010] Introducing the mixed solution into a polytetrafluoroethylene mold, drying and then cooling to room temperature, and taking it out of the mold to obtain the conductive film.

[0011] As a preferred scheme of the preparation method of the present invention, wherein: the ionic liquid includes 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide or 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide.

[0012] As a preferred embodiment of the preparation method of the present invention, wherein: the solvent includes dimethylformamide.

[0013] As a preferred embodiment of the preparation method of the present invention, wherein: the mass ratio of the PVDF (polyvinylidene fluoride) powder to the ionic liquid is 0.3 - 1.2:1.

[0014] As a preferred embodiment of the preparation method of the present invention, wherein: the ratio of the PVDF (polyvinylidene fluoride) powder to the solvent is 0.5 g:5 mL.

[0015] As a preferred embodiment of the preparation method of the present invention, wherein: for the water bath heating and stirring, the heating temperature is 20 - 60 °C, and the stirring reaction time is 20 - 120 min.

[0016] As a preferred embodiment of the preparation method of the present invention, wherein: for the drying, the drying temperature is 150 - 210 °C, and the time is 10 - 40 min.

[0017] Another object of the present invention is to overcome the deficiencies in the prior art and provide a conductive film, the thickness of the conductive film is 50 - 300 μm.

[0018] Another object of the present invention is to overcome the deficiencies in the prior art and provide an application of the conductive film in in vivo nerve signal acquisition and in vivo imaging.

[0019] Advantages of the present invention:

[0020] (1) The present invention provides a conductive film used as a cerebral cortex patch, which uses a flexible polymer as the electrode material, avoiding the damage to tissues caused by metal materials and the limitations on high - spatial imaging (such as magnetic resonance imaging, etc.).

[0021] (2) The present invention uses a commercial high - temperature - resistant and hydrophobic ionic liquid as the conductive medium, solving problems such as easy decomposition and easy leakage of common conductive hydrogels under high temperature and high voltage; the mass fraction of the ionic liquid has a linear relationship with conductivity, and it is difficult to achieve high conductivity with an ionic liquid doping amount below 50%; at the same time, the conflict between the transparency and conductivity of electronic conductors is solved through ionic conduction, achieving high conductivity (conductivity: 10 -3 S / cm -1 ) and high transparency (light transmittance: 75%). Description of the Drawings

[0022] To more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings. Among them:

[0023] Figure 1 It is the conductivity diagram of the membrane material in the embodiments of the present invention; wherein, A is the diagram of the influence of the ratio of ionic liquid to polyethylene (PVA), polyvinyl chloride (PVC), and PVDF on conductivity, B is the diagram of the influence of the doping amount of ionic liquid on the ionic conductivity of PVDF-IL, and C is the diagram of the ionic conduction activation energy in PVDF-IL.

[0024] Figure 2 It is the mechanical properties and X-ray scattering spectrum diagram of the membrane material in the embodiments of the present invention; wherein, A is the comparison diagram of Young's modulus and tensile strength with different doping amounts of ionic liquid, B is the stress curve of 70% PVDF-IL, C is the small-angle X-ray scattering (SAXS) spectrum, and D is the 2D-SAXS spectrum.

[0025] Figure 3 It is the ultraviolet absorption spectrum and photo diagram of the PVDF-IL membrane in the embodiments of the present invention.

[0026] Figure 4 It is the property analysis diagram of the PVDF-IL membrane in the embodiments of the present invention; wherein, A is the thermogravimetric result diagram of PVDF-IL in an inert gas and air atmosphere, B is the diagram of the mass and resistance change of PVDF-IL within 60 minutes at 50 °C, C is the diagram of the decomposition voltage tested by linear sweep voltammetry (LSV), and D is the cyclic voltammogram of the PVDF-IL electrode in different electrolyte solutions (deionized water, high-salt solution, physiological environment).

[0027] Figure 5 It is the diagram of the influence of different concentrations of leaching solution on the activity of Schwann cells cultured for 24 h in the embodiments of the present invention.

[0028] Figure 6 It is the photo diagram of the colony growth of Staphylococcus aureus and Escherichia coli in the embodiments of the present invention.

[0029] Figure 7 It is the diagram of the PVDF-IL electrode used to record the emotional changes of mice and the result diagram of optogenetic stimulation of brain signals in the embodiments of the present invention; wherein, (a) is the diagram of the PVDF-IL electrode used to record the emotional changes of mice, and (b) to (d) are the result diagrams of the PVDF-IL electrode used to record optogenetic stimulation of brain signals.

[0030] Figure 8This is the nuclear magnetic resonance image of the PVDF-IL electrode implanted in the mouse brain in the embodiment of the present invention. Detailed implementation manners

[0031] To make the above objects, features, and advantages of the present invention more obvious and understandable, the following will describe the detailed implementation manners of the present invention in conjunction with the embodiments of the specification.

[0032] In the following description, many specific details are set forth to fully understand the present invention. However, the present invention can also be implemented in other ways different from those described herein. Those skilled in the art can make similar generalizations without departing from the connotation of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed below.

[0033] Secondly, the so-called "one embodiment" or "embodiment" herein refers to a specific feature, structure, or characteristic that can be included in at least one implementation manner of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment that excludes other embodiments.

[0034] In the present invention, PVDF (polyvinylidene fluoride) is purchased from Aladdin Reagent Co., Ltd.; the ionic liquid is purchased from Aladdin Reagent Co., Ltd.

[0035] In the present invention, 0.5 g of PVDF (polyvinylidene fluoride) powder is mixed and dispersed with ionic liquids in different proportions (mass ratio) (IL: 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide salt or 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide salt) in 5 mL of dimethylformamide. After stirring and reacting in a water bath at 50 °C for 30 minutes; it is introduced into a 5 cm * 6 cm * 0.5 cm polytetrafluoroethylene mold and placed in an oven at 200 °C for 30 minutes and then cooled to room temperature;

[0036] The film material is taken out of the mold and can be cut into various properties for various characterizations.

[0037] Example 1

[0038] 0.5 g of PVDF (polyvinylidene fluoride) powder is mixed and dispersed with ionic liquids in different proportions (mass ratio) (IL: 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide salt liquid) in 5 mL of dimethylformamide. After stirring and reacting in a water bath at 50 °C for 30 minutes;

[0039] It is introduced into a 5 cm * 6 cm * 0.5 cm polytetrafluoroethylene mold, placed in an oven at 200 °C for 30 minutes and then cooled to room temperature, and the film material is taken out of the mold;

[0040] It is cut into a disk with a diameter of 1 cm and its thickness is measured using a thickness measuring instrument.

[0041] The conductivity was measured by the alternating current impedance technique using a CHI 660D electrochemical workstation (CHI Instruments, USA) in a two-probe electrochemical cell with a frequency range of 1 Hz - 1 MHz and an input voltage amplitude of 5 mV. The environmental temperature was controlled by an oven.

[0042] The conductivity calculation formula is as follows:

[0043]

[0044] Where L is the thickness (mm), R is the resistance (Ω), S is the tablet area (cm 2 ), and σ is the conductivity (S·cm -1 ). The resistance was calculated from the semicircle of the Nyquist plot. The activation energy value was obtained from the slope of the least-squares fitted line. The activation energy (Ea) was estimated by the following formula

[0045]

[0046] Where σ is the ionic conductivity, σ o is the pre-exponential factor, k is the Boltzmann constant, and T is the Kelvin temperature. Using ZView software, through equivalent circuit simulation, extrapolating the impedance data results, completing the Nyquist plot, and obtaining the resistance value.

[0047] And calculate its conductive activation energy, see Figure 1 ; where A is the graph of the influence of the ratio of ionic liquid to polyvinyl alcohol (PVA), polyvinyl chloride (PVC), and PVDF on conductivity, B is the graph of the influence of ionic liquid doping amount on the ionic conductivity of PVDF-IL, and C is the graph of the ionic conductive activation energy of different membranes in the examples of the present invention.

[0048] From Figure 1 A, it can be seen that as the amount of ionic liquid added increases, the conductivity of PVDF-IL continuously increases until it increases by more than three orders of magnitude, while the conductivities of PVA and PVC polymers are hardly affected by the change in ionic liquid content.

[0049] From Figure 1 B, it can be seen that when the ionic liquid content reaches 80%, the ionic conductivity can exceed 1 mS cm -1 . According to the ionic conductivity, the ionic conductive activation energy was calculated.

[0050] From Figure 1 C, it can be seen that in PVDF-IL (the mass fraction of ionic liquid is 80% for all), the activation energy for ion transfer is as high as 0.068 eV, far exceeding that of PVA-IL (0.039 eV) and PVC-IL (0.032 eV).

[0051] Example 2

[0052] 0.5 g of PVDF (polyvinylidene fluoride) powder was mixed and dispersed with ionic liquids (IL: 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide) in different ratios (mass fraction) in 5 mL of dimethylformamide. After stirring and reacting in a water bath at 50 °C for 30 minutes;

[0053] It was introduced into a 5 cm * 6 cm * 0.5 cm polytetrafluoroethylene mold and placed in an oven at 200 °C for 30 minutes, then cooled to room temperature;

[0054] The film material was taken out of the mold, cut into a 1 cm * 4 cm rectangle, and its mechanical properties were tested using a universal mechanical tester, and its crystal properties were determined using a small-angle X-ray diffractometer;

[0055] See Figure 2 , where A is the comparison of Young's modulus and tensile strength with different doping amounts of ionic liquids, B is the stress curve of 70% PVDF-IL, C is the small-angle X-ray scattering (SAXS) spectrum, and D is the 2D-SAXS spectrum.

[0056] It can be seen that as the content of the ionic liquid increases continuously, the Young's modulus of PVDF-IL shows a downward trend, indicating a weakening of the intermolecular interaction; although the Young's modulus of pure PVDF is very high, exceeding 120 MPa, its modulus has been reduced to less than 10 MPa through the doping of ionic liquids.

[0057] Only a shoulder peak was observed in the SXAS diagram ( Figure 2 C, D), indicating the existence of a structure larger than the detectable limit (>50 nm) of the current SAXS setting; this shoulder scattering peak comes from an ordered polymer crystal structure. With the addition of the ionic liquid, a new scattering peak appears, which represents the formation of disordered micelles. The formation of this disordered micelle destroys the original ordered rigid structure of the polymer, thus realizing the decrease of Young's modulus; the scattering peak of the micelle was also observed in the XRD test.

[0058] Example 3

[0059] 0.5 g of PVDF (polyvinylidene fluoride) powder was mixed and dispersed with 70% (mass fraction) of ionic liquid (IL: 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide) in 5 mL of dimethylformamide. After stirring and reacting in a water bath at 50 °C for 30 minutes;

[0060] It was introduced into a 5 cm * 6 cm * 0.5 cm polytetrafluoroethylene mold and placed in an oven at 200 °C for 30 minutes, then cooled to room temperature; the film material was taken out of the mold, cut into a disk with a diameter of 1 cm, and its transmittance was measured using a UV-visible spectroscopy instrument. The measurement results are as Figure 3as shown;

[0061] As can be seen from Figure 3 it, the transparency of the membrane exceeds 70%.

[0062] Example 4

[0063] 0.5 g of PVDF (polyvinylidene fluoride) powder was mixed and dispersed in 5 mL of dimethylformamide with 70% by mass of ionic liquid (IL: 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide), and after reacting with stirring in a water bath at 50 °C for 30 minutes;

[0064] It was introduced into a 5 cm * 6 cm * 0.5 cm polytetrafluoroethylene mold, placed in an oven at 200 °C for 30 minutes and then cooled to room temperature;

[0065] The membrane material was taken out of the mold, cut into discs with a diameter of 1 cm, and its thermal stability was measured using a thermogravimetric analyzer. Thermogravimetric analysis (TGA) was carried out by a Perkin-Elmer TGA-2 thermogravimetric analyzer, and the sample was heated from room temperature to 1000 °C at a heating rate of 10 °C / min in air or N2.

[0066] Its voltage stability and electrochemical stability were measured by a CHI660D electrochemical workstation: The decomposition voltages of PVDF-IL, hydrogel electrolyte (Neurospec, Switzerland) and PEDOSS:PSS conductive polymer (Heraeus, Germany) were tested using a two-electrode system, and the scanning rate was set to 0.5 mV s -1 in the range from 0 to 10 V; The material to be measured was clamped between two stainless steel electrodes and a voltage was applied;

[0067] To prove its stability in various solution environments, three environments were selected: low electrolyte strength solution (deionized water), high salt solution (3.4 w% NaCl) and physiological solution environment (1X PBS), and its aqueous solution stability was tested using a three-electrode system.

[0068] The measurement results are as Figure 4 shown. Among them, A is the thermogravimetric result diagram of PVDF-IL in an inert gas and air atmosphere. As can be seen from it, it is found through analysis that the mass of PVDF-IL remains constant below 300 °C whether in an inert gas environment or an argon atmosphere, while significant mass loss occurred in common commercial flexible sensors.

[0069] B is the change of the mass and resistance of PVDF-IL within 60 minutes at 50 °C. As can be seen from it, in an air environment at 50 °C, its mass loss within 60 minutes is only less than 1% and it does not cause an increase in resistance. The decomposition voltage found in the experimental results is several times higher than that of commercial hydrogels

[0070] C is the decomposition voltage tested by linear sweep voltammetry (LSV). It can be seen that as the applied voltage is too high, the current of the detected hydrogel and PEDOSS:PSS conductive polymer increases sharply. Bubbles are generated at the interface between the hydrogel electrode and the electrolyte, indicating that water is electrolyzed and decomposed. The PEDOSS:PSS conductive polymer undergoes a visible color change as the current increases, indicating that the material is damaged. PVDF-IL is quite stable throughout the voltage range, indicating that a higher voltage can be applied to the PVDF-IL electrode.

[0071] D is the cyclic voltammogram of the PVDF-IL electrode in different electrolyte solutions (deionized water, high-salt solution, physiological environment). It can be seen that after 100 cycles of operation in the three electrolyte environments, the cyclic voltammetry results are almost the same as before operation, indicating that PVDF-IL remains constant in various solution environments.

[0072] Example 5

[0073] 0.5 g of PVDF (polyvinylidene fluoride) powder is mixed and dispersed with 70% by mass of ionic liquid (IL: 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide) in 5 mL of dimethylformamide, and after stirring and reacting in a water bath at 50 °C for 30 minutes;

[0074] It is introduced into a 5 cm * 6 cm * 0.5 cm polytetrafluoroethylene mold, placed in an oven at 200 °C for 30 minutes and then cooled to room temperature; the film material is taken out of the mold.

[0075] The extraction of the leachate is carried out according to ISO 10993-5: Samples of 5 mm * 6 mm * 0.1 mm are sequentially immersed in ethanol and PBS solution (pH = 7, Biosharp) and irradiated with ultraviolet light for 2 h; then the materials are freeze-dried, weighed, and sterilized.

[0076] The sterilized materials are respectively immersed in deionized water and PBS, and cultured on a constant temperature shaker at 37 °C and 60 rpm for 24 h to obtain two leachates of 1 mg / ml -1 respectively;

[0077] The cytotoxicity is measured by the CCK-8 method: Different concentrations of leachate are added to Schwann cells, incubated for 24 h, 10 μl of CCK-8 solution is added, and then incubated for 4 h; after removing the supernatant, 100 μL of dimethyl sulfoxide is added to the wells.

[0078] The absorbance is measured by an enzyme-labeled instrument, and untreated cells are used as a control experiment. The effects of different concentrations of leachate on the activity of Schwann cells cultured for 24 h are shown in Figure 5 ;

[0079] It can be seen that after 24 hours of incubation in all experiments, the cell viability was greater than 95%, indicating that the cytotoxicity of PVDF-IL to RSC96 cells was negligible.

[0080] Example 6

[0081] 0.5 g of PVDF (polyvinylidene fluoride) powder was mixed and dispersed with 80% by mass of ionic liquid (IL: 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide) in 5 mL of dimethylformamide. After reacting with stirring in a water bath at 50 °C for 30 minutes;

[0082] It was introduced into a 5 cm * 6 cm * 0.5 cm polytetrafluoroethylene mold, placed in an oven at 200 °C for 30 minutes and then cooled to room temperature; the film material was taken out of the mold and cut into discs with a diameter of 1 cm.

[0083] The antibacterial activity of PVDF-IL was evaluated by the plate method:

[0084] The liquid LB medium used the formula: 10 g of tryptone, 5 g of yeast extract, 10 g of sodium chloride, and 1000 ml of double-distilled water. The solid medium (agar plate): On the basis of liquid LB, agar was added according to the standard of 15 g / L. The materials treated by ultraviolet sterilization were respectively placed in petri dishes, and the colonies of Staphylococcus aureus and Escherichia coli were cultured on the agar plate at 37 °C for 24 hours and then the experimental results were observed. See Figure 6 。

[0085] From Figure 6 it can be seen that there was hardly any difference in the number of colonies of Staphylococcus aureus and Escherichia coli between the blank group and the PVDF group. In contrast, when incubated with PVDF-IL, a significant reduction in bacteria was observed, indicating that PVDF-IL had an effective antibacterial efficiency.

[0086] Example 7

[0087] 0.5 g of PVDF (polyvinylidene fluoride) powder was mixed and dispersed with 80% by mass of ionic liquid (IL: 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide) in 5 mL of dimethylformamide. After reacting with stirring in a water bath at 50 °C for 30 minutes;

[0088] It was introduced into a 5 cm * 6 cm * 0.5 cm polytetrafluoroethylene mold, placed in an oven at 200 °C for 30 minutes and then cooled to room temperature;

[0089] The film material is taken out of the mold and cut into strips with a diameter of 1 * 0.3 cm as brain patches. The brain signals are measured by an in-vivo electrophysiological device. A small animal anesthesia machine is used to anesthetize the mice with 2% isoflurane and then fix them on the mouse brain stereotaxic apparatus. The head skin is cut open with surgical scissors to expose the skull. The mucous membrane and tissue on the surface of the skull are removed. A cranial drill is used to drill holes in the skull. The PVDF-IL electrode is implanted into the mouse brain (AP - 3.6 mm, ML - 2.4 mm, DV - 2.9 mm).

[0090] Two stainless steel micro-screws are fixed on the contralateral side as reference electrodes and ground electrodes. After the PVDF electrode is implanted into the designated area, dental cement is used to fix the electrode on the skull to prevent relative displacement of the electrode. The detection channels are connected to a brain signal acquisition system (to amplify the signals. The whole recording process is carried out in a self-built shielding box, and the signal acquisition frequency is 30 kHz).

[0091] Adeno-associated virus (rAAV-hSyn-ChrimsonR-tdTomato, 5 μl) is injected into the right hippocampus of the mouse (AP - 3.6 mm, ML - 2.4 mm, DV - 0.2 mm).

[0092] Four weeks after the injection, the PVDF-IL electrode is connected to the optical fiber and inserted through the previously drilled micro-holes in the mouse skull, and is activated by 475 nm laser light pulses.

[0093] Electrophysiological recordings are made using a brain signal acquisition system, as Figure 7 shown. The brain patches can record the changes in brain signals caused by emotional changes in mice and the changes in brain epidermal signals under optogenetic stimulation.

[0094] Example 8

[0095] 0.5 g of PVDF (polyvinylidene fluoride) powder is mixed and dispersed with different proportions of ionic liquid (IL: 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide) in 5 mL of dimethylformamide. After reacting with stirring in a water bath at 50 °C for 30 minutes;

[0096] It is introduced into a 5 cm * 6 cm * 0.5 cm polytetrafluoroethylene mold, placed in an oven at 200 °C for 30 minutes and then cooled to room temperature;

[0097] The film material was removed from the mold and cut into discs with a diameter of 3 mm. It was implanted into the mouse brain and attached to the cerebral cortex of the hippocampal region, and then magnetic resonance imaging was performed (Sagittal parameters: TE = 8.9 ms, TR = 450 ms, slice thickness = 1.5 mm; Coronal parameters: TE = 11.7 ms, TR = 250 ms, slice thickness = 2 mm; Axial parameters: TE = 8.8 ms, TR = 600 ms, slice thickness = 1.5 mm). As Figure 8 shown, it can be seen that the implantation of the electrode patch has no effect on the nuclear magnetic resonance imaging.

[0098] In the present invention, the base material used must be PVDF. Using other polymers such as PVA / PVC as the base material will cause the conductivity to decrease by 3-6 orders of magnitude; the conductive ions used must be ionic liquids. Using other salts as ionic additives will cause a significant decrease in conductivity.

[0099] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the spirit and scope of the technical solutions of the present invention, and they should all be covered within the scope of the present invention.

Claims

1. A method for preparing a conductive film used as a cerebral cortex patch, characterized in that: including, Mix PVDF (polyvinylidene fluoride) powder with an ionic liquid and disperse them in a solvent, then heat and stir in a water bath to obtain a mixed solution; Pour the mixed solution into a polytetrafluoroethylene mold, dry it and then cool it to room temperature, and take it out of the mold to obtain the conductive film.

2. The preparation method according to claim 1, characterized in that: The ionic liquid includes 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide or 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide.

3. The preparation method according to claim 1 or 2, characterized in that: The solvent includes dimethylformamide.

4. The preparation method according to claim 1, characterized in that: The mass ratio of the PVDF (polyvinylidene fluoride) powder to the ionic liquid is 0.3 - 1.2:

1.

5. The preparation method according to claim 1 or 4, characterized in that: The ratio of the PVDF (polyvinylidene fluoride) powder to the solvent is 0.5 g:5 mL.

6. The preparation method according to claim 1, characterized in that: For the heating and stirring in the water bath, the heating temperature is 20 - 60 °C and the stirring reaction time is 20 - 120 min.

7. The preparation method according to claim 1, characterized in that: For the drying, the drying temperature is 150 - 210 °C and the time is 10 - 40 min.

8. The conductive film prepared by the preparation method according to any one of claims 1 to 7, characterized in that: The thickness of the conductive film is 50 - 300 μm.

9. Application of the conductive film according to claim 8 in in-vivo nerve signal acquisition and in-vivo imaging.

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