阅读说明：本技术 一种电极及其制备方法和应用 (Electrode and preparation method and application thereof ) 是由 刘杨 殷鹏飞 肖林 张超 于 2021-08-10 设计创作，主要内容包括：本发明公开了一种电极及其制备方法和应用。一种电极,包括：铝微丝,铝微丝的直径在25～127μm之间；导电聚合物涂层,导电聚合物涂层包裹于铝微丝表面,组分包括聚吡咯和聚(3,4-乙烯二氧噻吩)中的至少一种。本发明提出的电极,以铝微丝替代其他贵金属微丝电极,降低了成本；将铝微丝与导电聚合物涂层相结合,提升了电极与生物体之间的相容性。(The invention discloses an electrode and a preparation method and application thereof. An electrode, comprising: the diameter of the aluminum microwire is 25-127 mu m; the conductive polymer coating is wrapped on the surface of the aluminum microfilament, and the component comprises at least one of polypyrrole and poly (3, 4-ethylenedioxythiophene). According to the electrode provided by the invention, the aluminum microwire is used for replacing other noble metal microwire electrodes, so that the cost is reduced; the aluminum microwire is combined with the conductive polymer coating, so that the compatibility between the electrode and organisms is improved.)

1. An electrode, comprising:

the diameter of the aluminum microwire is 25-127 mu m;

the conductive polymer coating is wrapped on the surface of the aluminum microfilament, and the components of the conductive polymer coating comprise at least one of polypyrrole and poly (3, 4-ethylenedioxythiophene).

2. The electrode according to claim 1, wherein the aluminum microwire comprises aluminum with a mass fraction of 99.99% or more; preferably, the electrode is a bioelectrode.

3. A method of preparing an electrode according to claim 1 or 2, comprising the steps of:

s1, carrying out surface treatment on the aluminum microfilament;

s2, depositing the conductive polymer coating on the surface of the aluminum microwire obtained in the step S1.

4. The method according to claim 3, wherein in step S1, the surface treatment is performed by an electrochemical method; preferably, the electrochemical method is a galvanostatic method.

5. The method according to claim 4, wherein the electrolyte is a first mixed aqueous solution in which solutes including nitric acid and pyrrole; preferably, the concentration of nitric acid in the first mixed aqueous solution is 0.05 to 0.15M, and the concentration of pyrrole in the first mixed aqueous solution is 0.05 to 0.15M.

6. The method according to claim 4, wherein the constant current method is used, and the current is 50-500 μ A; preferably, the treatment time of the constant current method is 60-120 s.

7. The method according to claim 3, wherein in step S2, the conductive polymer coating is deposited by electrodeposition; preferably, the electrodeposition method is cyclic voltammetry.

8. The method according to claim 7, wherein the electrolyte is a second mixed aqueous solution in which the solute includes oxalic acid and a monomer of a polymer; preferably, the polymer monomer comprises at least one of pyrrole and 3, 4-ethylenedioxythiophene; preferably, in the second mixed aqueous solution, the concentration of the oxalic acid is 0.05 to 0.15M, and the concentration of the polymer monomer is 0.5M.

9. The method according to claim 7, wherein in the cyclic voltammetry, the initial value of the sweep voltage is about-0.1V, and the final value is between 2.0 and 3.0V; preferably, the scanning rate of the cyclic voltammetry is between 5 and 100 mV/s; further preferably, the cyclic voltammetry has 5-20 cycles.

10. A nerve detection device comprising the electrode according to any one of claims 1 to 2 or the electrode produced by the production method according to any one of claims 3 to 9.

Technical Field

The invention belongs to the technical field of bioelectrode, and particularly relates to an electrode and a preparation method and application thereof.

Background

With the increasing aging population, more and more people are suffering from neurological diseases. The neural interface is a new means for diagnosing and treating the above-mentioned diseases, and is favored by doctors and researchers, and plays a very important role in the field of neurology-related research. The nerve electrode is a part in the nerve interface which is directly contacted with nerve tissues, can record the electrophysiological activity of neurons, and takes a recorded signal as the basis for diagnosing the neurogenic disease; an electrical signal of a particular amplitude and frequency may also be externally applied to the nerve tissue for stimulating and activating neuronal activity to ameliorate nerve dysfunction.

At present, commonly used metal electrodes can be classified into metal microwire electrodes (such as tungsten, platinum iridium electrodes, etc.) and silicon-based metal microelectrode arrays (such as utah electrodes and michigan electrodes, etc.). These electrodes, while successful to some extent, have some problems: 1. the mechanical properties of the electrode material are not matched with those of the nerve tissues, and after the electrode is implanted into the nerve tissues for a long time, the electrode can be subjected to severe tissue reaction to cause abnormal work, and needs to be taken out by a secondary operation, so that the physical and economic burden of a patient is increased; 2. signal sensitivity, biological safety and the like need to be improved; 3. the noble metal electrode has the characteristics of scarce raw materials, higher cost and difficulty in large-scale preparation and application; the microelectrode array has complicated preparation process and structure.

In conclusion, the existing electrode for the neural interface has the problems of high price, complex preparation process and poor biocompatibility.

Disclosure of Invention

The present invention is directed to solving at least one of the problems of the prior art described above. Therefore, the invention provides the electrode, the aluminum microwire is used for replacing other noble metal microwire electrodes, and the cost is reduced; the aluminum microwire is combined with the conductive polymer coating, so that the compatibility between the electrode and organisms is improved.

The invention also provides a preparation method of the electrode.

The invention also provides a nerve detection device comprising the electrode or the electrode prepared by the preparation method.

According to an aspect of the present invention, there is provided an electrode comprising:

the diameter of the aluminum microwire is 25-127 mu m;

the conductive polymer coating is wrapped on the surface of the aluminum microfilament, and the components of the conductive polymer coating comprise at least one of polypyrrole and poly (3, 4-ethylenedioxythiophene).

According to a preferred embodiment of the present invention, at least the following advantages are provided:

(1) compared with the traditional noble metal microwire electrode, the electrode takes the aluminum microwire as the main base material, and the aluminum has good toughness, ductility and conductivity, so that the electrode has the electrical property equivalent to that of the noble metal microwire electrode; meanwhile, the raw material cost of the electrode is reduced due to the low price of the raw material.

(2) Compared with the traditional microelectrode array, the electrode provided by the invention has a simple structure, so that the preparation process is simplified, and the yield of the obtained electrode is improved.

(3) Compared with a bare metal electrode (comprising a metal microwire electrode and a microelectrode array), the electrode provided by the invention can realize long-term implantation of the electrode in a biological body and keep stable performance due to the surface modification of the conductive polymer coating, and in addition, the conductive polymer coating can effectively improve the mechanical matching degree, biocompatibility and physiological electrochemical performance between the electrode and biological tissues.

(4) The conductive polymer coating can obviously improve the charge storage capacity of the aluminum microwire, reduce the impedance of the aluminum microwire, and obviously improve the stability and biocompatibility of the aluminum microwire.

In some embodiments of the invention, the electrode is a bioelectrode.

In some preferred embodiments of the present invention, the bioelectrode comprises a nerve electrode.

The bioelectrode or the nerve electrode can be used for extracting the nerve signals of the prefrontal cortex of the brain of the SD rat.

In some embodiments of the present invention, the aluminum microwire has a mass fraction of aluminum greater than or equal to 99.99%.

In some embodiments of the invention, the conductive polymer coating, component(s), comprises polypyrrole.

In some embodiments of the present invention, the conductive polymer coating has a thickness of 5 to 31 μm.

In some embodiments of the invention, the electrode further comprises a connector, one end of the connector is connected with the aluminum microwire, and the other end of the connector is connected with an external device.

In some embodiments of the invention, the connector comprises a probe directly connected to the external device, a copper strip directly connected to the aluminum microwire, and a wire connecting the probe and the copper strip. In some embodiments of the present invention, the probe is made of copper.

In some embodiments of the invention, the probe has a diameter of 0.6 to 1.6mm and a total length of 6 to 16 mm.

In some preferred embodiments of the present invention, the probe has a diameter of about 1mm and a total length of about 10 mm.

In some preferred embodiments of the present invention, the conductive wire is made of silver with a purity of 99.99% or more.

In some embodiments of the invention, the wire is wound from one or more strands of silver wire.

In some preferred embodiments of the present invention, the wire is wound by 2 strands of silver wire.

In some embodiments of the invention, the silver wire has a diameter of 0.4 to 0.9 mm.

In some preferred embodiments of the present invention, the silver wire has a diameter of about 0.64 mm.

Because the aluminum microwire has small size, and an electrode formed by the aluminum microwire needs to be implanted into an organism, the size requirement is fine; therefore, the copper strip is fixed and then connected with the lead.

In the connecting piece, the electrical conductivity of copper (probe) and silver (wire) is higher, and the silver has the corrosion-resistant characteristic, so that the precision and the service life of the electrode can be improved.

In the connector, the sizes of the probe, the lead and the copper strip are matched with external equipment (a clamp of the electrophysiological measurement device).

According to still another aspect of the present invention, there is provided a method for preparing the electrode, comprising the steps of:

s1, carrying out surface treatment on the aluminum microfilament;

s2, depositing the conductive polymer coating on the surface of the aluminum microwire obtained in the step S1.

The preparation method according to a preferred embodiment of the present invention has at least the following advantageous effects:

different organisms or different parts of the same organism have different requirements on parameters such as the size of the bioelectrode; the preparation method provided by the invention has wide application range, and the electrodes with the aluminum microwires with different diameters and the conductive polymer coatings with different thicknesses and densities can be obtained by adjusting the size of the aluminum microwire raw material and the deposition process in the step S2, so that the corresponding implantation scheme is met.

In some embodiments of the present invention, in step S1, the aluminum micro wires are connected to an external device through a connector.

In some embodiments of the present invention, in step S1, the surface treatment is performed by an electrochemical method.

In some embodiments of the invention, the electrochemical process is a galvanostatic process.

In some embodiments of the invention, the electrolyte is a first mixed aqueous solution in which the solutes comprise nitric acid and pyrrole.

In some embodiments of the invention, the concentration of nitric acid in the first mixed aqueous solution is 0.05 to 0.15M, and the concentration of pyrrole in the first mixed aqueous solution is 0.05 to 0.15M.

In some preferred embodiments of the present invention, the concentration of nitric acid in the first mixed aqueous solution is about 0.1M and the concentration of pyrrole in the first mixed aqueous solution is about 0.1M.

In the first mixed aqueous solution, the nitric acid is used for providing protons (hydrogen ions) required for etching the surface of the aluminum wire, and the pyrrole is used for adsorbing the surface of the etched aluminum wire to serve as a polymerization center in the polymerization deposition process of the next step.

According to the observation by a scanning electron microscope, no significant polypyrrole deposits were formed in step S1.

In some embodiments of the present invention, the constant current method has a current of 50-500 μ A.

In some embodiments of the present invention, the treatment time of the constant current method is 60 to 120 s.

In some preferred embodiments of the present invention, the constant current method has a treatment time of about 90 s.

In step S1, the surface treatment functions to form the aluminum micro-wires into a rough surface to facilitate the deposition of the conductive polymer in step S2.

In some embodiments of the present invention, in step S2, the conductive polymer coating is deposited by electrodeposition.

In some embodiments of the invention, the electrodeposition method is cyclic voltammetry.

In some embodiments of the present invention, the electrolyte is a second mixed aqueous solution in which the solute includes oxalic acid and a polymer monomer.

In some embodiments of the invention, the polymer monomer comprises at least one of pyrrole and 3, 4-ethylenedioxythiophene.

In some embodiments of the present invention, the concentration of the oxalic acid in the second mixed aqueous solution is 0.05 to 0.15M, and the concentration of the monomer is 0.25 to 0.75M. In some preferred embodiments of the present invention, the concentration of the oxalic acid in the second mixed aqueous solution is about 0.1M, and the concentration of the monomer is about 0.5M.

In some embodiments of the present invention, the cyclic voltammetry is performed at a sweep voltage starting value of about-0.1V and ending value of between 2.0 and 3.0V.

In some embodiments of the invention, the cyclic voltammetry has a sweep voltage in the range of-1.0 to 2.0V; -1.0-2.5V; -1.0-3.0V.

In some embodiments of the present invention, the cyclic voltammetry is performed at a sweep rate of between 5 and 100 mV/s.

In some embodiments of the invention, the cyclic voltammetry, scan rate is 5mV/s, 25 mV/s; 50 mV/s; 100 mV/s.

In some embodiments of the present invention, the cyclic voltammetry has between 5 and 20 cycles.

In some embodiments of the invention, the cyclic voltammetry for 5 cycles; 10 circles; one of 20 turns.

In some embodiments of the invention, the electrochemical process and the electrodeposition are both performed using a three-electrode system.

In some embodiments of the invention, the three-electrode system, the working electrode is the aluminum microwire, the counter electrode is a platinum wire electrode, and the reference electrode is Ag/AgCl.

According to still another aspect of the present invention, there is provided a nerve detection device comprising the electrode or the electrode produced by the production method.

In some embodiments of the invention, the neural detection device can perform neural signal detection.

In some embodiments of the invention, the nerve detection device may also deliver a signal stimulus to the contacted nerve.

Drawings

The invention is further described with reference to the following figures and examples, in which:

FIG. 1 is a diagram showing the components obtained in step D1 in example 1 of the present invention;

FIG. 2 is an SEM image of the aluminum microfilament raw material used in examples 1 to 8 of the present invention;

FIG. 3 is an SEM image of electrodes obtained in examples 1 to 3 of the present invention;

FIG. 4 is an SEM image of the electrodes obtained in examples 3 to 5 of the present invention;

FIG. 5 is an SEM image of electrodes obtained in examples 3, 6 and 8 of the present invention;

FIG. 6 is an SEM image of the aluminum microfilament raw material used in examples 9 to 18 of the present invention;

FIG. 7 is an SEM image of electrodes obtained in examples 9 to 11 of the present invention;

FIG. 8 is an SEM photograph of electrodes obtained in examples 11 to 13 of the present invention;

FIG. 9 is an SEM image of electrodes obtained in examples 9, 14 and 15 of the present invention;

FIG. 10 shows CV diagrams and EIS diagrams of electrodes obtained in examples 1 to 3 of the present invention;

FIG. 11 shows CV diagrams and EIS diagrams of electrodes obtained in examples 3 to 5 of the present invention;

FIG. 12 shows CV diagrams and EIS diagrams of the electrodes obtained in examples 3, 6 to 7 of the present invention;

FIG. 13 shows CV diagrams and EIS diagrams of electrodes obtained in examples 9 to 11 of the present invention;

FIG. 14 is a CV diagram and an EIS diagram of the electrodes obtained in examples 11 to 13 of the present invention;

FIG. 15 shows CV diagrams and EIS diagrams of electrodes obtained in examples 9, 14 to 15 of the present invention;

FIG. 16 is an EIS diagram of the aluminum microwire material used in example 16 of the present invention and the resulting electrode;

FIG. 17 is a CV diagram of an electrode obtained in comparative example 1 of the present invention;

FIG. 18 is a plot of polarization of the aluminum microwire feedstock used in example 7 of the present invention and the resulting electrode;

FIG. 19 shows the results of in vitro cytotoxicity experiments on aluminum microfilament materials and resulting electrodes used in example 7 of the present invention, (A) rat fibroblast cells 3T3, (B) PC12 cells;

FIG. 20 shows the staining results of live/dead cells after co-culturing 3T3 cells with the aluminum microfilament material used in example 7 of the present invention and the resulting electrode for 24 hours;

FIG. 21 shows the neural signals extracted from the implantation of the aluminum microwire material used in example 7 of the present invention into the cerebral cortex of rats, (a) the aluminum microwire material, (b) the electrode obtained in example 7;

reference numerals:

100. a conductive polymer coating; 200. aluminum microwires; 300. copper strips; 400. a wire; 500. a probe; 600. and (7) welding points.

Detailed Description

The concept and technical effects of the present invention will be clearly and completely described below in conjunction with the embodiments to fully understand the objects, features and effects of the present invention. It is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments, and those skilled in the art can obtain other embodiments without inventive effort based on the embodiments of the present invention, and all embodiments are within the protection scope of the present invention.

In the description of the present invention, if there are first and second described only for the purpose of distinguishing technical features, it is not understood that relative importance is indicated or implied or that the number of indicated technical features or the precedence of the indicated technical features is implicitly indicated or implied. Unless otherwise expressly limited, terms such as set, mounted, connected and the like are to be construed broadly, and those skilled in the art can reasonably determine the specific meaning of the terms in the present invention by combining the detailed contents of the technical solutions.

Example 1

In this example, an electrode was prepared, and the specific process was:

D1. fixing an aluminum microwire 200 with the diameter of 127 mu m by a copper strip, connecting the copper strip 300 with a silver lead 400, connecting the silver lead with a copper probe 500 through a welding spot 600 formed by soldering, and connecting the copper probe 500 with external equipment;

D2. taking one side of the aluminum microwire of the component obtained in the step D1 as a working electrode, taking a platinum wire electrode as a counter electrode and taking Ag/AgCl as a reference electrode, and activating the aluminum microwire by adopting a constant current method;

wherein in the constant current method, the adopted current is 500 muA;

the activation time is 90 s;

the electrolyte is a mixed aqueous solution formed by nitric acid and pyrrole, wherein the concentration of the nitric acid is 0.1M, and the concentration of the pyrrole is 0.1M;

after activating the aluminum microwire, washing the aluminum microwire with deionized water (at least three times) and drying;

D3. d2, taking one side of the aluminum microwire of the component as a working electrode, taking a platinum wire electrode as a counter electrode and taking Ag/AgCl as a reference electrode, and depositing a conductive polymer coating 100 on the surface of the aluminum microwire obtained in the step D2 by adopting a cyclic voltammetry method;

in the cyclic voltammetry, the scanning voltage range is-1.0-2.0V; the scanning rate is 50 mV/s; the number of scanning turns is 10 turns;

the electrolyte is a mixed aqueous solution formed by oxalic acid and pyrrole, wherein the concentration of the oxalic acid is 0.1M, and the concentration of the pyrrole is 0.5M.

The resulting part of this example, step D1, is shown in FIG. 1.

Examples 2 to 18 each prepared an electrode, which was different from example 1 in the parameters of each step, and the specific parameters are shown in table 1, wherein (D1) indicates that the parameters correspond to step D1.

TABLE 1 parameter tables for examples 1-16

Comparative example 1

This comparative example prepared an electrode, the specific procedure differed from example 1 in that:

t1, fixing an aluminum micro-wire with the diameter of 127 mu m by using a copper strip, connecting the copper strip with a silver lead, connecting the silver lead with a copper probe through a welding spot formed by tin soldering, and connecting the copper probe with external equipment;

D2. taking one side of the aluminum microwire of the component obtained in the step D1 as a working electrode, taking a platinum wire electrode as a counter electrode and taking Ag/AgCl as a reference electrode, and depositing 1 mu m of aluminum on the surface of the aluminum microwire; wherein the electrolyte is a mixed aqueous solution of 0.1M aluminum chloride and 0.1M formic acid;

D3. d2, taking one side of the aluminum microwire of the component obtained in the step D as a working electrode, taking a platinum wire electrode as a counter electrode and taking Ag/AgCl as a reference electrode, and depositing a conductive gel soft interface on the surface of the aluminum microwire obtained in the step D2 by adopting a constant voltage method;

wherein in the constant voltage method, the voltage is 0.05V; the deposition time is 5 h; the electrolyte is 2 wt% of PPy: PSS electrolyte.

Test example 1

The experimental example detects the shapes of the aluminum microwire raw material and the obtained electrode; the morphology testing method is a scanning electron microscope method.

The shapes of the aluminum microwire raw materials used in the examples 1-8 are shown in FIG. 2;

the morphology of the aluminum microwire raw materials used in examples 9-16 is shown in fig. 6, and the information in the figure shows that the aluminum microwire without any treatment has a smoother morphology and no granular coating is attached to the surface, and the comparison with the morphology of the electrode obtained in the examples shows that the polypyrrole coating can be attached to the surface of the aluminum microwire by the preparation method provided by the invention.

The morphology of the electrodes obtained in examples 1 to 3 is shown in FIG. 3 (diameter of aluminum microwire is 127 μm), and the SEM images of the electrodes obtained in examples 9 to 11 are shown in FIG. 7 (diameter of aluminum microwire is 25 μm); respectively corresponding to different termination voltages of cyclic voltammetry; the results show that: the polypyrrole coating prepared by the cyclic voltammetry has a surface which is of a fine structure similar to cauliflower, is rough and has a certain micro-nano hierarchical structure, the thickness of the polypyrrole coating on the surface of the aluminum microfilament is gradually increased along with the increase of the termination scanning voltage of the cyclic voltammetry, and meanwhile, the surface roughness of the polypyrrole coating is increased and the granular sensation is enhanced. The average thickness of the polypyrrole coating in each example is as follows: 7.7 μm in example 1, 8.0 μm in example 2, 8.7 μm in example 3, 5.5 μm in example 9, 15.0 μm in example 10, and 15.5 μm in example 11,

the morphology of the electrodes obtained in examples 3 to 5 is shown in FIG. 4 (diameter of aluminum microwire is 127 μm), and the SEM images of the electrodes obtained in examples 11 to 13 are shown in FIG. 8 (diameter of aluminum microwire is 25 μm); respectively corresponding to different cycle numbers of cyclic voltammetry; the results show that: the morphology in fig. 4 is similar to that in fig. 3, and as the number of cyclic voltammetry cycles increases, the thickness of the polypyrrole coating on the surface of the aluminum microwire gradually increases, and meanwhile, the surface roughness of the polypyrrole coating increases, and the granular sensation increases. In each example, the average thickness of the polypyrrole coating was as follows: 5.6 μm in example 4, 8.7 μm in example 3, and 9.0 μm in example 5.

The morphology of the electrodes obtained in examples 3, 6 and 8 is shown in FIG. 5 (the diameter of the aluminum microwire is 127 μm), and the SEM images of the electrodes obtained in examples 9, 14 to 15 of the present invention are shown in FIG. 9 (the diameter of the aluminum microwire is 25 μm); respectively corresponding to different scanning speeds of cyclic voltammetry; the results show that the morphology in fig. 5 is similar to the morphology in fig. 3, and the thickness of the polypyrrole coating on the surface of the aluminum microwire gradually decreases with the increase of the cyclic voltammetry scanning speed, and meanwhile, the surface roughness of the polypyrrole coating decreases and the granular sensation decreases. The thickness of the polypyrrole coating in each example was: 30.5 μm in example 8, 8.7 μm in example 3, and 7.4 μm in example 6.

In conclusion, polypyrrole coatings of different thicknesses can be easily prepared by controlling the voltage range, the number of scanning cycles, the scanning rate and the like of the CV.

Test example 2

In this test example, CV (cyclic voltammetry) and EIS (alternating current impedance) tests of the electrodes obtained in examples and comparative examples were first performed, and specific test methods were as follows:

performing CV test, wherein the scanning voltage is-0.8V, the scanning speed is 100mV/s, and the number of scanning turns is 5 turns;

the EIS test frequency range is 10-100000 Hz, the voltage is 0V, and the amplitude is 10 mV;

the CV and EIS tests both used a three-electrode system, the electrodes prepared in the examples were used as working electrodes, platinum wire electrodes as counter electrodes, Ag/AgCl electrodes as reference electrodes, and the electrolyte solution was a simulated body fluid (PBS solution (phosphate balanced physiological saline) with pH 7.0).

Specific results are shown in FIGS. 10 to 17; the result shows that CV spectra of the electrode obtained in the embodiment all show excellent physiological and electrochemical performance; however, in the electrode obtained in comparative example 1, the soft interface of the conductive gel formed on the surface of the aluminum-based microwire is not continuous, and a silvery white bare aluminum part can be seen by naked eyes; it can be seen from the CV chart (fig. 17) that the cyclic voltammetry curves of the electrode obtained in comparative example 1 are not connected end to end and hysteresis is generated during the positive and negative voltage direction conversion, indicating that the stability and electrochemical reversibility of the coating are poor. At the end of the test, the fracture phenomenon of the coated aluminum-based microwire positioned on the working electrode is found, and the poor stability of the electrode prepared by the process is reflected.

Then, for the implantable neural electrode prepared by the invention, the physiological and electrochemical performance determines the capability of the implantable neural electrode to extract and stimulate neural tissue signals, i.e. the neural electrode should have higher cathode Charge Storage Capacity (CSC)_c) And lower impedance (EI). The test results showed that the electrodes prepared in each example had the best physioelectrochemical performance when the CV voltage was in the range of-1.0 to 3.0V, the scan rate was 25mV/s, and the number of scan cycles was 10 (examples 7 and 11), as shown in Table 2,

in the second column, q represents the product of the cathode capacity and the sweep rate, and the right side of the equal sign is a calculation formula of the parameter;

in the third column, Q (C) means the cathode capacity in coulombs (C), and the right side of the equal sign is the calculation formula of the parameter;

in the fourth column, A (cm)²) Meaning the geometric surface area of the working electrode in cm²；

In the last column, EI at 1kHz (Ω) means that when the ac frequency is 1kHz, the impedance of the resulting electrode is in Ω, and the test method is described in "m.r. abidian et al, adv.mater, 2009,21, 3764-.

CSC_cThe values can be tested by the method disclosed in reference "S.F. Cogan, Annu.Rev. biomed.Eng.,2008,10,275-_cRespectively 0.25, 0.55, 2.8mC cm^-2。

TABLE 2 results of the electrochemical and physiological performances of the electrodes obtained in the examples

In addition, the results shown in fig. 16 also show that the impedance value of the electrode obtained in example 16 is lower than that of the aluminum microwire raw material used in example 16 at any frequency, which indicates that the polypyrrole coating can not only improve the corrosion resistance of the aluminum microwire, but also effectively improve the physiological electrochemical performance of the aluminum microwire.

Test example 3

In this test example, a polarization curve test was performed on uncoated aluminum microwires (aluminum microwire raw material used in example 7) and the electrode obtained in example 7 by a dynamic voltage method to evaluate the corrosion resistance of the electrode obtained in example 7, the test method comprising the steps of:

a three-electrode system is adopted, the electrode obtained in example 7 is used as a working electrode, a platinum wire electrode is used as a counter electrode, an Ag/AgCl electrode is used as a reference electrode, and an electrolyte solution is artificial cerebrospinal fluid with the pH value of 6.5; the dynamic voltage range is-0.6V, and the scanning rate is 5 mV/s.

From the results of the polarization curves of FIG. 18, it can be seen that the corrosion current density of the aluminum microwires in the artificial cerebrospinal fluid was from 5.01. mu.A/cm due to the presence of the polypyrrole coating²The concentration is reduced to 3.16 mu A/cm²And calculating to obtain the corrosion rate of 5.46 multiplied by 10^{- 2}mm/year is reduced to 3.44X 10^-2mm/year, which shows that the polypyrrole coating can effectively slow down the corrosion rate of the aluminum microwire, thereby being beneficial to enhancing the implantation stability of the aluminum microwire electrode.

Test example 4

This experimental example tested the biocompatibility of the electrode obtained in the example. The method specifically comprises the following steps:

uncoated aluminum microwires (aluminum microwire starting material used in example 7) and the electrodes from example 7 were first co-cultured in vitro with 3T3 cells or PC12 cells, respectively, for 24h to assess the biocompatibility of the electrodes. The specific evaluation method comprises the following steps:

1) soaking the aluminum microwire and the electrode in deionized water for one week to remove impurities, unreacted monomers and the like on the surface of the material; during the period, deionized water is replaced at least three times per day; finally, placing the cleaned aluminum microwires and the electrode in an oven at 30 ℃ for overnight drying;

2) cutting the dried aluminum microfilament and the electrode into short rods with the length of 2mm, and sterilizing for 12h under ultraviolet light;

3) 3T3 or PC12 cells were seeded in 96-well plates and incubated at 37 ℃ with 5% CO₂Culturing for 24 hours in an incubator in the environment of (1);

4) adding the 2mm long aluminum microfilament or electrode obtained in the step 3) into a pore plate of 3T3 cells or PC12 cells for co-culture for 24h, obtaining test results by using a CCK-8 method and staining live cells/dead cells of the 3T3 cells to observe the final morphology of the cells.

The results of the in vitro cell assay are shown in FIG. 19, in which panel A shows the results of the assay on rat fibroblast 3T3 and panel B shows the results of the assay on PC12 cells; the results show that: compared with a blank control group, the uncoated aluminum microwire has certain toxicity to 3T3 cells and PC12 cells, but the electrode introduced with the polypyrrole coating obviously improves the cell compatibility of the aluminum microwire, so that the cell survival rates of the 3T3 and the PC12 are both more than 95%;

FIG. 20 is the results of a cell staining test in which the first row, as viewed in rows, is a control, i.e., a simple cell culture, with no aluminum microwires or electrodes added, the second row with 2mm long aluminum microwires added, and the third row with 2mm long electrodes added; the first column is the result of staining live cells, the second is the result of staining dead cells, and the third is the result of staining all cells, as listed;

the cell staining experiment in fig. 20 also demonstrates that the viable number of cells after co-culture with cells was higher for the electrode incorporating the polypyrrole coating compared to the aluminum microfilament feedstock, indicating that it was more biocompatible with cells and did not inhibit their proliferation; wherein the size of the white scale in fig. 20 is 100 μm.

Thereafter, the aluminum microwire material used in example 7 and the resulting electrode were implanted into the cerebral cortex of SD rats, respectively, to extract nerve signals, and the signal results are shown in fig. 21, which shows that the electrode obtained in example 7 (fig. 21B) has higher definition and signal-to-noise ratio when used for the extraction of nerve signals of SD rats, compared to the aluminum microwire material (fig. 21A).

The embodiments of the present invention have been described in detail with reference to the accompanying drawings, but the present invention is not limited to the above embodiments, and various changes can be made within the knowledge of those skilled in the art without departing from the gist of the present invention. Furthermore, the embodiments of the present invention and the features of the embodiments may be combined with each other without conflict.