Conductive hydrogel for neural electrode as well as preparation method and application of conductive hydrogel

Abstract

The invention provides conductive hydrogel for a neural electrode and a preparation method and application of the conductive hydrogel. The conductive hydrogel comprises a polymer three-dimensional network, and a conductive polymer and Lewis acid are doped in the hydrogel; and the conductive polymer is subjected to phase separation under the action of the Lewis acid to form a conductive network. The conductive hydrogel has excellent conductivity and mechanical properties, and also has good biocompatibility.

Description

Technical Field

[0001] The invention belongs to the field of neural electrodes and relates to a conductive hydrogel for neural electrodes and a preparation method and application thereof. Background Art

[0002] Flexible neural electrodes have broad application prospects in the field of neural signal detection due to their high degree of match with neural tissue and their ability to adapt to micro-movements of brain tissue, which can reduce tissue damage and inflammatory response after implantation, and help achieve more stable and long-term neural recordings. Conductive hydrogels used for flexible neural electrodes have become a very potential alternative to traditional metal neural electrodes in the field of brain-computer interface bioelectronic interfaces due to their similarity to biological tissues (high water content, softness) and conductivity. Among them, conductive polymer hydrogels (conductive hydrogels based on conductive polymers) show a series of advantages compared with other conductive hydrogels based on metals (such as silver, gold, platinum) or carbon nanomaterials (such as carbon nanotubes, graphene and their derivatives), including good electrical properties, physiological environment stability and biocompatibility.

[0003] Although some progress has been made in the development of hydrogels that mimic the mechanical properties of biological tissues, the research on conductive polymer hydrogels with good mechanical properties remains challenging. Existing tough conductive polymer hydrogels, which are usually prepared by mixing or polymerizing conductive polymers in a tough hydrogel matrix, show low conductivity due to the low connectivity between the conductive phases in the hydrogel and / or the high stiffness and low water content that are different from biological tissues. High conductivity is usually achieved by increasing the conductive polymer content (e.g., pure conductive polymer hydrogels), which greatly reduces the mechanical properties of the hydrogel and limits their utility in flexible neural electrodes. This is because flexible neural electrodes need to have both good mechanical and electrical properties in order to effectively reduce the inflammatory response caused by the neural electrode as a foreign body and improve the signal-to-noise ratio of recorded neural electrical signals.

[0004] Therefore, it is very important to develop a conductive hydrogel that has both tissue-like mechanical properties and high electrical conductivity. Summary of the invention

[0005] In order to solve the technical problems existing in the prior art, the present invention provides a conductive hydrogel for neural electrodes and a preparation method and application thereof. The conductive hydrogel has excellent conductive properties and mechanical properties as well as good biocompatibility.

[0006] In order to achieve the above technical effects, the present invention adopts the following technical solutions:

[0007] One of the purposes of the present invention is to provide a conductive hydrogel for neural electrodes, the conductive hydrogel comprising a polymer three-dimensional network, wherein the hydrogel is doped with a conductive polymer and a Lewis acid;

[0008] The conductive polymer undergoes phase separation under the action of the Lewis acid to form a conductive network.

[0009] As a preferred technical solution of the present invention, the conductive polymer is poly(3,4-ethylenedioxythiophene)-poly(styrene sulfonic acid).

[0010] As a preferred technical solution of the present invention, the Lewis acid includes any one of sodium chloride, magnesium chloride, indium chloride, nickel chloride or ferric chloride, or a combination of at least two thereof.

[0011] As a preferred technical solution of the present invention, the polymer three-dimensional network is obtained by polymerizing unsaturated-sulfobetaine monomers and a crosslinking agent.

[0012] As a preferred technical solution of the present invention, the unsaturated sulfobetaine includes methacryloylethyl sulfobetaine.

[0013] And / or, the cross-linking agent comprises N,N'-methylenebisacrylamide.

[0014] The second object of the present invention is to provide a method for preparing the conductive hydrogel for neural electrodes provided by the first object, the preparation method comprising:

[0015] Mixing polymer monomers, photoinitiators and conductive polymer solutions required for forming the polymer three-dimensional network, and performing photopolymerization reaction to obtain a template hydrogel;

[0016] The template hydrogel is immersed in the Lewis acid aqueous solution to obtain the conductive hydrogel.

[0017] As a preferred technical solution of the present invention, the mass fraction of the conductive polymer in the conductive polymer solution is 1 to 1.3%.

[0018] And / or, the mass ratio of the unsaturated sulfobetaine to the conductive polymer is 20 to 120:1.

[0019] And / or, the mass ratio of the unsaturated sulfobetaine to the cross-linking agent is 500-1000:1.

[0020] And / or, the mass ratio of the unsaturated sulfobetaine to the photoinitiator is 5000-10000:1.

[0021] As a preferred technical solution of the present invention, the mass concentration of the Lewis acid aqueous solution is 10-30%.

[0022] As a preferred technical solution of the present invention, the template hydrogel is immersed in anhydrous ethanol for 2 to 4 hours before being immersed in the Lewis acid aqueous solution.

[0023] And / or, after the template hydrogel is immersed in the Lewis acid aqueous solution, it is immersed in a buffer solution with a pH value of 7 to 7.4 for 48 to 72 hours.

[0024] The third object of the present invention is to provide an application of the conductive hydrogel for neural electrodes provided in the first object, wherein the conductive hydrogel is used for preparing neural electrodes for monitoring cerebral cortical field potential signals.

[0025] Compared with the prior art, the present invention has at least the following beneficial effects:

[0026] (1) The present invention provides a conductive hydrogel for neural electrodes and a preparation method and application thereof. The conductive hydrogel has excellent conductive properties and mechanical properties. The conductivity of the conductive hydrogel is 3.2 to 9.2 S / m, and the Young's modulus can reach 16.85 kPa.

[0027] (2) The present invention provides a conductive hydrogel for neural electrodes and a preparation method and application thereof, wherein the conductive hydrogel has good biocompatibility.

[0028] (3) The present invention provides a conductive hydrogel for neural electrodes and a preparation method and application thereof. The flexible neural electrodes prepared with the conductive hydrogel are used to record LFP signals of the cerebral cortex, which can improve the signal-to-noise ratio thereof. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 A schematic flow chart of a method for preparing a conductive hydrogel provided in a specific embodiment of the present invention.

[0030] Figure 2 This is a tensile stress-strain curve of the conductive hydrogel prepared in Example 4 of the present invention.

[0031] Figure 3 This is a graph showing the Young's modulus data of the conductive hydrogels prepared in Examples 1-6 of the present invention.

[0032] Figure 4 This is a scanning electron microscope (SEM) image of the conductive hydrogel prepared in Example 4 of the present invention after freeze-drying.

[0033] Figure 5 The conductivity diagram of the hydrogels prepared in Examples 4 and 7-11 of the present invention after being treated with Lewis acid solutions of different types and concentrations.

[0034] Figure 6This is a graph showing the conductivity change of the conductive hydrogel prepared in Examples 1-6 of the present invention after being immersed in phosphate buffer for 14 days.

[0035] Figure 7 Impedance spectra of an unmodified bare gold electrode and a gold electrode modified with conductive hydrogel prepared in Example 4 at different frequencies.

[0036] Figure 8 The impedance change at a frequency of 1000 Hz of the gold electrode modified with the conductive hydrogel prepared in Example 4 after being immersed in phosphate buffer for 14 days.

[0037] Fig. 9 This is a comparison of live-dead staining of mouse hippocampal neuron cells (HT22) cultured using the conductive hydrogel leaching medium prepared in Example 4 and the control group medium that has not undergone any treatment.

[0038] Fig.10 This is a comparison diagram of the long-term monitoring of LFP signals in the cerebral cortex of normal rats using the conductive hydrogel-polyimide film electrode prepared in Example 4 and the pure polyimide film electrode.

[0039] The present invention is further described in detail below. However, the following examples are only simplified examples of the present invention and do not represent or limit the scope of protection of the present invention. The scope of protection of the present invention shall be subject to the claims. DETAILED DESCRIPTION

[0040] The technical solution of the present application is further described below through specific implementation methods.

[0041] A specific embodiment of the present invention provides a conductive hydrogel for a neural electrode, the conductive hydrogel comprising a polymer three-dimensional network, wherein the hydrogel is doped with a conductive polymer and a Lewis acid;

[0042] The conductive polymer undergoes phase separation under the action of the Lewis acid to form a conductive network.

[0043] In the present invention, the introduced Lewis acid cations interact with the negatively charged conductive polymers, so that the conductive polymers undergo phase separation, and the conductive polymers form a conductive network for further connection, thereby improving the conductivity of the hydrogel.

[0044] In a specific embodiment of the present invention, the conductive polymer is poly(3,4-ethylenedioxythiophene)-poly(styrene sulfonic acid) (PEDOT:PSS). PEDOT and PSS are phase separated under the action of the conductive polymer, and the PEDOT conductive network is further connected.

[0045] In one embodiment of the present invention, the Lewis acid comprises any one of sodium chloride, magnesium chloride, indium chloride, nickel chloride or ferric chloride, or a combination of at least two thereof.

[0046] In one specific embodiment of the present invention, the three-dimensional polymer network is obtained by polymerizing an unsaturated-sulfobetaine monomer and a crosslinking agent.

[0047] In one embodiment of the present invention, the unsaturated sulfobetaine comprises methyl methacryloylethyl sulfobetaine (SBMA).

[0048] In one embodiment of the present invention, the cross-linking agent comprises N,N'-methylenebisacrylamide (MBAA).

[0049] In the present invention, due to the super hydrophilicity of the zwitterionic polymer polymethacrylate sulfobetaine, the conductivity of the conductive hydrogel is further improved, and the conductive hydrogel also has the characteristics of low Young's modulus and good biocompatibility.

[0050] A specific embodiment of the present invention provides a method for preparing a conductive hydrogel for a neural electrode, the preparation method comprising:

[0051] Mixing polymer monomers, photoinitiators and conductive polymer solutions required for forming the polymer three-dimensional network, and performing photopolymerization reaction to obtain a template hydrogel;

[0052] The template hydrogel is immersed in the Lewis acid aqueous solution to obtain the conductive hydrogel.

[0053] In a specific embodiment of the present invention, the mass fraction of the conductive polymer in the conductive polymer solution is 1-1.3%, such as 1%, 1.1%, 1.2% or 1.3%, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0054] In a specific embodiment of the present invention, the mass ratio of the unsaturated sulfobetaine to the conductive polymer is 20 to 120:1, such as 20:1, 30:1, 40:1, 50:1, 60:1, 70:1, 80:1, 90:1, 100:1, 110:1 or 120:1, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0055] In a specific embodiment of the present invention, the mass ratio of the unsaturated group-sulfobetaine to the cross-linking agent is 500 to 1000:1, such as 500:1, 600:1, 700:1, 800:1, 900:1 or 1000:1, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0056] In a specific embodiment of the present invention, the mass ratio of the unsaturated sulfobetaine to the photoinitiator is 5000-10000:1, such as 5000:1, 6000:1, 7000:1, 8000:1, 9000:1 or 10000:1, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0057] In one specific embodiment of the present invention, the photoinitiator is preferably 2-hydroxy-2-methyl-1-phenylpropanone (1173).

[0058] In a specific embodiment of the present invention, the polymer monomers required for the polymer three-dimensional network, the photoinitiator and the conductive polymer solution are mixed under light-proof conditions for 1 to 2 hours.

[0059] In a specific embodiment of the present invention, the photopolymerization reaction is carried out under ultraviolet light conditions, and the reaction time is 1 to 1.5 hours.

[0060] In one specific embodiment of the present invention, the wavelength of the ultraviolet light may be 302 nm.

[0061] In a specific embodiment of the present invention, the mass concentration of the Lewis acid aqueous solution is 10-30%, such as 10%, 12%, 15%, 18%, 20%, 22%, 25%, 28% or 30%, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0062] In a specific embodiment of the present invention, the template hydrogel is immersed in the Lewis acid aqueous solution for 72 to 96 hours, such as 72 hours, 76 hours, 80 hours, 84 hours, 88 hours, 92 hours or 96 hours, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0063] In a specific embodiment of the present invention, the template hydrogel is immersed in an anhydrous ethanol solution for 2 to 4 hours, such as 2h, 2.2h, 2.5h, 2.8h, 3h, 3.2h, 3.5h, 3.8h or 4h before being immersed in the Lewis acid aqueous solution, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0064] In a specific embodiment of the present invention, after the template hydrogel is immersed in the Lewis acid aqueous solution, it is immersed in a buffer solution with a pH value of 7 to 7.4 for 48 to 72 hours. The pH can be 7, 7.1, 7.2, 7.3 or 7.4, etc., and the immersion time can be 48 hours, 54 hours, 60 hours, 66 hours or 72 hours, etc., but it is not limited to the listed values, and other values ​​not listed in the above ranges are also applicable.

[0065] To better illustrate the present invention and facilitate understanding of the technical solution of the present invention, typical but non-limiting embodiments of the present invention are as follows:

[0066] Example 1

[0067] This embodiment provides a method for preparing a conductive hydrogel for a neural electrode, the process of which is as follows: Figure 1 As shown, the preparation method comprises:

[0068] 0.4 g SBMA monomer, 0.44 mg MBAA crosslinker and 0.047 mg photoinitiator 1173 were dissolved in 2 mL PEDOT:PSS (1 wt%) solution, stirred at room temperature in the dark for 1 h, and then cured under 302 nm UV light for 1 h to obtain a template hydrogel;

[0069] The template hydrogel was sequentially immersed in anhydrous ethanol for 4 hours, immersed in a 30wt% NaCl solution for 96 hours, and immersed in a phosphate buffer solution with a pH of 7 to 7.4 for 48 hours to obtain a conductive hydrogel with a mass ratio of SBMA monomer to PEDOT:PSS of 20:1.

[0070] Example 2

[0071] This embodiment provides a method for preparing a conductive hydrogel for a neural electrode, the preparation method comprising:

[0072] 0.8 g SBMA monomer, 0.88 mg MBAA crosslinker and 0.094 mg photoinitiator 1173 were dissolved in 2 mL PEDOT:PSS (1 wt%) solution, stirred at room temperature in the dark for 1 h, and then cured under 302 nm UV light for 1 h to obtain a template hydrogel;

[0073] The template hydrogel was sequentially immersed in anhydrous ethanol for 4 hours, in a 30wt% NaCl solution for 96 hours, and in a phosphate buffer solution with a pH of 7 to 7.4 for 48 hours to obtain a conductive hydrogel with a mass ratio of SBMA monomer to PEDOT:PSS of 40:1.

[0074] Example 3

[0075] This embodiment provides a method for preparing a conductive hydrogel for a neural electrode, the preparation method comprising:

[0076] 1.2 g SBMA monomer, 1.32 mg MBAA crosslinker and 0.141 mg photoinitiator 1173 were dissolved in 2 mL PEDOT:PSS (1 wt%) solution, stirred at room temperature in the dark for 1 h, and then cured under 302 nm UV light for 1 h to obtain a template hydrogel;

[0077] The template hydrogel was sequentially immersed in anhydrous ethanol for 4 h, in a 30 wt % NaCl solution for 96 h, and in a phosphate buffer solution with a pH of 7 to 7.4 for 48 h to obtain a conductive hydrogel with a mass ratio of SBMA monomer to PEDOT:PSS of 60:1.

[0078] Example 4

[0079] This embodiment provides a method for preparing a conductive hydrogel for a neural electrode, the preparation method comprising:

[0080] 1.6 g SBMA monomer, 0.88 mg MBAA crosslinker and 0.094 mg photoinitiator 1173 were dissolved in 2 mL PEDOT:PSS (1 wt%) solution, stirred at room temperature in the dark for 1 h, and then cured under 302 nm UV light for 1 h to obtain a template hydrogel;

[0081] The template hydrogel was sequentially immersed in anhydrous ethanol for 4 hours, in a 30wt% NaCl solution for 96 hours, and in a phosphate buffer solution with a pH of 7 to 7.4 for 48 hours to obtain a conductive hydrogel with a mass ratio of SBMA monomer to PEDOT:PSS of 80:1.

[0082] Example 5

[0083] This embodiment provides a method for preparing a conductive hydrogel for a neural electrode, the preparation method comprising:

[0084] 2.0 g SBMA monomer, 1.1 mg MBAA crosslinker and 0.118 mg photoinitiator 1173 were dissolved in 2 mL PEDOT:PSS (1 wt%) solution, stirred at room temperature in the dark for 1 h, and then cured under 302 nm UV light for 1 h to obtain a template hydrogel;

[0085] The template hydrogel was sequentially immersed in anhydrous ethanol for 4 h, immersed in a 30 wt % NaCl solution for 96 h, and immersed in a phosphate buffer solution with a pH of 7 to 7.4 for 48 h to obtain a conductive hydrogel with a mass ratio of SBMA monomer to PEDOT:PSS of 100:1.

[0086] Example 6

[0087] This embodiment provides a method for preparing a conductive hydrogel for a neural electrode, the preparation method comprising:

[0088] 2.4 g SBMA monomer, 1.32 mg MBAA crosslinker and 0.141 mg photoinitiator 1173 were dissolved in 2 mL PEDOT:PSS (1 wt%) solution, stirred at room temperature in the dark for 1 h, and then cured under 302 nm UV light for 1 h to obtain a template hydrogel;

[0089] The template hydrogel was sequentially immersed in anhydrous ethanol for 4 h, in a 30 wt % NaCl solution for 96 h, and in a phosphate buffer solution with a pH of 7 to 7.4 for 48 h to obtain a conductive hydrogel with a mass ratio of SBMA monomer to PEDOT:PSS of 120:1.

[0090] Example 7

[0091] This embodiment provides a method for preparing a conductive hydrogel for a neural electrode. The preparation method is the same as that of Embodiment 4 except that the concentration of sodium chloride is replaced with 0wt%, 10wt% and 20wt%.

[0092] Example 8

[0093] This embodiment provides a method for preparing a conductive hydrogel for a neural electrode. The preparation method is the same as that of Example 4 except that sodium chloride is replaced by magnesium chloride, and the magnesium chloride is 0wt%, 10wt%, 20wt% and 30wt%.

[0094] Example 9

[0095] This embodiment provides a method for preparing a conductive hydrogel for a neural electrode. The preparation method is the same as that of Embodiment 8 except that magnesium chloride is replaced by indium chloride.

[0096] Example 10

[0097] This embodiment provides a method for preparing a conductive hydrogel for a neural electrode. The preparation method is the same as that of Embodiment 8 except that magnesium chloride is replaced by nickel chloride.

[0098] Embodiment 11

[0099] This embodiment provides a method for preparing a conductive hydrogel for a neural electrode. The preparation method is the same as that of Embodiment 8 except that magnesium chloride is replaced by ferric chloride.

[0100] Performance Test 1

[0101] The tensile properties of the conductive hydrogel obtained in Example 4 were tested on a universal material tester 3365. Figure 2 It can be seen that the hydrogel has good tensile properties, with a maximum elongation greater than 170%.

[0102] Performance Test 2

[0103] The tensile properties of the conductive hydrogels obtained in Examples 1-6 were tested on a universal material tester 3365, and the Young's modulus data were calculated by Figure 3As shown, it can be seen that the Young's modulus of the conductive hydrogels with a mass ratio of SBMA monomer to PEDOT:PSS of 80:1, 100:1, and 120:1 is lower, which is more consistent with the modulus of brain tissue.

[0104] Performance Test 3

[0105] The internal structure of the conductive hydrogel obtained in Example 4 was tested on a field ring scanning electron microscope tester, and the operation method thereof includes:

[0106] The prepared hydrogel was placed in liquid nitrogen, then freeze-dried, sprayed with gold at 25 mA for 3 min, and the microscopic morphology of the hydrogel was observed by scanning electron microscopy (eg Figure 4 As shown). Scanning electron microscopy shows that the conductive hydrogel has a microscopic porous structure.

[0107] Performance Test 4

[0108] The conductivity of the hydrogels treated with Lewis acid solutions of different types and concentrations provided in Examples 4 and 7-11 was tested by ST2242 four-probe instrument. Figure 5 As shown, it can be seen that the hydrogel treated with 30% NaCl solution has the highest conductivity.

[0109] Performance Test 5

[0110] The conductivity change of hydrogels with different SBMA monomer and PEDOT:PSS mass ratios treated with 30% NaCl solution was tested by ST2242 four-probe instrument after being immersed in phosphate buffer for 14 days. Figure 6 As shown, it can be seen that the conductivity of the conductive hydrogel tends to stabilize after the second day.

[0111] Performance Test 6

[0112] The changes in impedance at different frequencies before and after modification of the conductive hydrogel provided in Example 4 were tested by an electrochemical workstation using a three-electrode system, in which the reference electrode was an Ag / AgCl electrode and the counter electrode was a platinum sheet electrode. The final results are as follows: Figure 7 As shown, after the conductive hydrogel was modified, the impedance was significantly reduced when the frequency was less than 10000.

[0113] Performance Test 7

[0114] The electrochemical workstation was used to continue monitoring the impedance change at a frequency of 1000 Hz of the gold electrode modified with the conductive hydrogel provided in Example 4 after being immersed in phosphate buffer for 14 days. Figure 8 As shown, the impedance remains basically stable.

[0115] Performance Test 8

[0116] The dead / live cell staining method is used to determine the cell survival and cell proliferation of HT22 cells in the conductive hydrogel leaching medium in Example 4, and the operation method includes:

[0117] The conductive hydrogel prepared in Example 4 was placed in 20 mL of culture medium for 400 mg and incubated at 37° C. for 24 h. The culture medium after the hydrogel was soaked was filtered with a filter to obtain a conductive hydrogel leaching culture medium. The culture medium without incubation sample was used as the control group.

[0118] HT22 cells were cultured in the above two culture media for 1 day, then the culture media were removed, washed with phosphate buffer for 3 times, and measured using a Live / dead kit. Cell activity was observed under a laser confocal microscope at an excitation wavelength of 488 / 561 nm; live cells were stained with calcein to emit green fluorescence, and dead cells were stained with propidium iodide to emit red fluorescence.

[0119] like Fig. 9 The cell survival in the conductive hydrogel group was similar to that in the control group, indicating that the conductive hydrogel had almost no cytotoxicity and good biocompatibility.

[0120] Performance Test Nine

[0121] With the help of the stereotaxic instrument, a 5x5 mm cranial window was opened in the rat's brain, and the conductive hydrogel-polyimide film electrode or polyimide film electrode was attached to the cranial window and fixed with dental cement. After the electrode implantation process is completed, the electrophysiological instrument can be used to monitor the LFP signal of the rat's cerebral cortex at the specified time. The two-week long-term signal monitoring results are as follows Fig.10 As shown, the signal-to-noise ratio of the signal measured by the electrode modified with the conductive hydrogel provided in Example 4 is higher than that of the unmodified electrode, and the polyimide film electrode modified with the conductive hydrogel can stably monitor the LFP signal within two weeks.

[0122] The applicant declares that the present invention illustrates the detailed structural features of the present invention through the above embodiments, but the present invention is not limited to the above detailed structural features, that is, it does not mean that the present invention must rely on the above detailed structural features to be implemented. Those skilled in the art should understand that any improvement of the present invention, equivalent replacement of the components selected by the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

[0123] The preferred embodiments of the present invention are described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, a variety of simple modifications can be made to the technical solution of the present invention, and these simple modifications all belong to the protection scope of the present invention.

[0124] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations.

[0125] In addition, various embodiments of the present invention may be arbitrarily combined, and as long as they do not violate the concept of the present invention, they should also be regarded as the contents disclosed by the present invention.

Claims

1. A conductive hydrogel for neural electrodes, characterized in that: The conductive hydrogel comprises a three-dimensional polymer network, and the hydrogel is doped with a conductive polymer and a Lewis acid; The conductive polymer undergoes phase separation under the action of the Lewis acid to form a conductive network.

2. The conductive hydrogel according to claim 1, characterized in that: The conductive polymer is poly(3,4-ethylenedioxythiophene)-poly(styrene sulfonic acid).

3. The conductive hydrogel according to claim 1, characterized in that: The Lewis acid includes any one of sodium chloride, magnesium chloride, indium chloride, nickel chloride or ferric chloride, or a combination of at least two thereof.

4. The conductive hydrogel according to claim 1, characterized in that The polymer three-dimensional network is obtained by polymerizing unsaturated-sulfobetaine monomers and a crosslinking agent.

5. The conductive hydrogel according to claim 4, characterized in that: The unsaturated-sulfobetaine includes methacryloylethylsulfobetaine; And / or, the cross-linking agent comprises N,N'-methylenebisacrylamide.

6. A method for preparing a conductive hydrogel for neural electrodes according to any one of claims 1 to 5, characterized in that: The preparation method comprises: Mixing polymer monomers, photoinitiators and conductive polymer solutions required for forming the polymer three-dimensional network, and performing photopolymerization reaction to obtain a template hydrogel; The template hydrogel is immersed in the Lewis acid aqueous solution to obtain the conductive hydrogel.

7. The preparation method according to claim 6, characterized in that: The mass fraction of the conductive polymer in the conductive polymer solution is 1 to 1.3%; And / or, the mass ratio of the unsaturated sulfobetaine to the conductive polymer is 20 to 120:1; And / or, the mass ratio of the unsaturated-sulfobetaine to the cross-linking agent is 500-1000:1; And / or, the mass ratio of the unsaturated sulfobetaine to the photoinitiator is 5000-10000:

1.

8. The preparation method according to claim 6, characterized in that: The mass concentration of the Lewis acid aqueous solution is 10-30%.

9. The preparation method according to claim 6, characterized in that: The template hydrogel is soaked in anhydrous ethanol for 2 to 4 hours before being soaked in the Lewis acid aqueous solution; And / or, after the template hydrogel is immersed in the Lewis acid aqueous solution, it is immersed in a buffer solution with a pH value of 7 to 7.4 for 48 to 72 hours.

10. An application of the conductive hydrogel for neural electrodes according to any one of claims 1 to 5, characterized in that: The conductive hydrogel is used for preparing a neural electrode for monitoring cerebral cortical field potential signals.

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