Carbon nanotube / conducting polymer composite material, application and carbon nanotube composite nerve probe electrode

Abstract

The invention belongs to the field of carbon nano tube composite materials, and relates to a carbon nano tube / conducting polymer composite material, application and a carbon nano tube composite nerve probe electrode. The composite material is composed of a single carbon nano tube and / or carbon nano tube bundle fiber, the surface of which is coated with a conductive polymer, and the coverage rate of the conductive polymer is more than 80%. The invention provides a novel carbon-based biological composite material and a preparation method thereof, and the novel carbon-based biological composite material can be used for manufacturing a subcellular chronic nerve probe, has good electrical performance and can be used for long-term stable signal recording and physiological monitoring.

Description

Technical Field

[0001] This invention belongs to the field of carbon nanotube composite materials, specifically, it relates to a carbon nanotube / conductive polymer composite material, its preparation method and application, and a carbon nanotube composite neural probe electrode prepared using the composite material. Background Technology

[0002] The detection and recording of chronic neural signals in vivo is a significant challenge for brain-computer interface electrode arrays. Compared to other detection methods, such as high-performance liquid chromatography coupled with offline electrochemistry, in vivo electrochemical detection based on tissue-implanted fiber electrodes offers higher spatiotemporal resolution and can accurately measure chemically unstable substances. Currently, implantable electrical stimulation neuromodulation has become an important clinical treatment for various neurological (Parkinson's disease, epilepsy, etc.) and psychiatric (depression) diseases. Neural interfaces serve as a direct bridge for information exchange between external electronic devices and neural tissue, primarily composed of neural electrodes. Highly spatially selective, long-term implantable neural stimulation electrodes are crucial for achieving high-precision electrical stimulation neuromodulation. Ideal stimulation electrodes require small size, good biocompatibility, strong charge injection capability, and mechanical properties that match the tissue.

[0003] Carbon nanotube fiber electrodes hold promise as ideal implantable neural electrodes for long-term electrostimulation of neuromodulation. Research teams from Tsinghua University, Shanghai Jiao Tong University's School of Biomedical Engineering, Case Western Reserve University, and Rice University have demonstrated that carbon nanotube fiber materials possess high charge injection capabilities, promising wide applications in the biomedical field. For example, carbon nanotube fiber electrodes can promote the migration and growth of various cells on their surface and can also be used for biomarker sensing. However, due to electrode contamination, the signal stability of bare carbon nanotube fibers for detecting some low-dose neurochemicals is limited. For instance, ascorbic acid in the central nervous system undergoes slow electron transfer on the surface of the fiber electrode, often resulting in large overpotentials during its electrochemical oxidation process and affecting the electrode's selectivity for ascorbic acid. Considering the sensitivity of these neurochemicals to the chemical state of the electrode surface, a common optimization method is to improve the electron transfer kinetics of ascorbic acid oxidation through pre-activation of the fiber electrode. However, under the same conditions, electrodes activated with these pre-activation methods often fail to yield highly reproducible analytical results. On the other hand, constructing carbon nanotube fiber composite neural electrodes, such as coating the fiber surface with an electrocatalyst, can not only effectively improve the electron transfer rate but also improve the repeatability of the electrochemical behavior of the fiber electrode, which is of great significance in detecting neurochemicals and monitoring physiological activities.

[0004] Furthermore, the size effect and mechanical properties of carbon nanotube fibers must be considered. Submicron-diameter carbon nanotube bundles or single ultra-long carbon nanotubes with nanometer-diameters can achieve better contact and binding with nerve synapses. As the electrodes become smaller, the damage caused during implantation is relatively reduced, allowing for the simultaneous placement of more electrodes in specific areas and avoiding the need for implantation from other locations. Simultaneously, these high aspect ratio ultra-long carbon nanotube fibers exhibit better anisotropy and flexibility, with a lower elastic modulus compared to traditional Pt / Ir alloy wires. This significantly improves mechanical compatibility with biological tissues and provides excellent bending flexibility stability, overcoming the challenges of long-term implantation in vivo. Summary of the Invention

[0005] The purpose of this invention is to provide a composite material and process method for coating high aspect ratio carbon nanotubes with a conductive polymer as an electrocatalyst for long-term stable detection of subcellular chronic neural signals, in order to prepare ultra-miniature carbon nanotube composite neural electrodes, providing an advanced material basis for the development of long-term, high-quality, and selective neural interfaces.

[0006] A first aspect of the present invention provides a carbon nanotube / conductive polymer composite material, the composite material being composed of single carbon nanotubes and / or carbon nanotube bundle fibers coated with a conductive polymer, wherein the coverage of the conductive polymer is 80% or more, preferably 85% or more.

[0007] A second aspect of the present invention provides a method for preparing the above-described carbon nanotube / conductive polymer composite material, comprising the following steps:

[0008] (1) Obtain carbon nanotubes, wherein the carbon nanotubes are in the form of horizontally arrayed carbon nanotubes or carbon nanotube films.

[0009] (2) Electrodeposit the conductive polymer on the surface of the carbon nanotube.

[0010] A third aspect of the present invention provides the application of the above-described carbon nanotube / conductive polymer composite material in the preparation of electrodes.

[0011] A fourth aspect of the present invention provides a carbon nanotube composite neural probe electrode, the probe electrode comprising a probe electrode body and an electrode material loaded thereon, the electrode material being the aforementioned carbon nanotube / conductive polymer composite material.

[0012] The fifth aspect of the present invention provides a method for preparing the above-mentioned carbon nanotube composite neural probe electrode, comprising: bringing the probe electrode body close to the carbon nanotube / conductive polymer composite material, and pulling out a single carbon nanotube or carbon nanotube bundle fiber by relying on van der Waals interactions to obtain the carbon nanotube composite neural probe electrode.

[0013] Compared to existing technologies, this invention provides a novel carbon-based biocomposite material and its preparation method, which can be used to fabricate subcellular chronic neural probes with excellent electrical properties for long-term stable signal recording and physiological monitoring. The ultra-miniature probe electrode based on this advanced biocomposite material will make a significant contribution to the development of long-term, high-quality, and selective neural electrode interfaces, bringing a revolutionary change to the fields of brain-computer interfaces and neuroprosthetics.

[0014] Other features and advantages of the present invention will be described in detail in the following detailed description section. Attached Figure Description

[0015] Exemplary embodiments of the present invention will be described in more detail with reference to the accompanying drawings.

[0016] Figure 1 The flowchart of the preparation of carbon nanotube composite neural probe electrodes according to the present invention is shown.

[0017] Figure 2 An optical microscope image of a carbon nanotube composite neural probe electrode prepared according to a specific embodiment of the present invention is shown. Detailed Implementation

[0018] The following provides a detailed description of specific embodiments of the present invention. It should be understood that the specific embodiments described herein are for illustrative and explanatory purposes only and are not intended to limit the scope of the invention.

[0019] The present invention provides a carbon nanotube / conductive polymer composite material, wherein the composite material is composed of single carbon nanotubes and / or carbon nanotube bundle fibers coated with conductive polymer, wherein the coverage of the conductive polymer is 80% or more, preferably 85% or more.

[0020] The composite material of the present invention preferably uses high aspect ratio carbon nanotubes, which refer to carbon nanotubes with an aspect ratio of 1000:1 or higher.

[0021] According to a preferred embodiment of the present invention, the carbon nanotubes are ultra-long carbon nanotubes. Specifically, preferably, the length of the carbon nanotubes is 5 to 1000 mm, the diameter is 0.7 to 5 nm, and the diameter of the bundled fibers is 0.5 to 10 μm.

[0022] The length of ultralong carbon nanotubes can be listed as any value from 5mm, 10mm, 20mm, 50mm, 100mm, 200mm, 300mm, 400mm, 500mm, 600mm, 700mm, 800mm, 900mm, 1000mm, or any combination of two of the above values.

[0023] For a single ultra-long carbon nanotube, its length can be tens of millimeters or more. For bundled fibers, its length is comparable to the width of the slit in the silicon substrate, usually a few millimeters.

[0024] According to the present invention, the coating can be achieved using various common types of conductive polymers. Preferably, the conductive polymer is selected from at least one of polyaniline, polypyrrole, PEDOT and PSS, with PEDOT being the most preferred.

[0025] This invention provides a method for preparing the above-mentioned carbon nanotube / conductive polymer composite material, comprising the following steps:

[0026] (1) Obtain carbon nanotubes, wherein the carbon nanotubes are in the form of horizontally arrayed carbon nanotubes or carbon nanotube films.

[0027] (2) Electrodeposit the conductive polymer on the surface of the carbon nanotube.

[0028] The methods for obtaining carbon nanotubes are well known to those skilled in the art. For the horizontal array of carbon nanotubes, they can be prepared on the substrate surface by chemical vapor deposition.

[0029] The substrate can be any one of silicon, silicon / silicon oxide, highly oriented pyrolytic graphite, quartz, and sapphire. According to one specific embodiment of the present invention, the substrate is a silicon / silicon oxide substrate with a plurality of slits etched with a width of 1–10 mm.

[0030] According to a preferred embodiment of the present invention, the method for preparing the horizontal array carbon nanotubes includes: loading a catalyst onto a substrate and placing it in a reactor; reducing the catalyst by introducing a protective gas; then introducing a mixed reaction gas of carbon source and hydrogen and heating the reaction to prepare the horizontal array carbon nanotubes; the catalyst is preferably a chloride of at least one metal selected from Fe, Mo, Cu and Cr, and most preferably a FeCl3 catalyst.

[0031] Specific reaction conditions may include: the protective gas being argon or a mixture of argon and hydrogen, with a flow rate of 150–250 sccm and a volume ratio of 1:1.5–3; the flow rate of the mixed reaction gas of carbon source and hydrogen being 150–200 sccm; the reaction temperature being 900–1010℃; and the reaction time being 20–60 min.

[0032] According to a specific embodiment of the present invention, the preparation method of horizontal array carbon nanotubes includes: pressing an ethanol solution of 0.02M to 0.04M FeCl3 catalyst onto a growth substrate, introducing a mixture of argon and hydrogen at 150 to 250 sccm as a protective gas, and after the temperature rises to 900 to 1010°C, maintaining the temperature for 10 to 30 minutes to enter the reaction stage, introducing a mixture of methane and hydrogen at 150 to 200 sccm (H2:CH4 = 1 to 3:1), and reacting for 20 to 60 minutes.

[0033] The above-mentioned steps for preparing carbon nanotubes can also be found in Chinese Patent No. CN102001643B, "An Ultra-Long Carbon Nanotube and Its Preparation Method," filed by the applicant on December 8, 2010, and published on August 7, 2013. For the sake of brevity, this patent is cited here only, but all technical content of the aforementioned patent should also be considered part of the technical disclosure of this invention.

[0034] According to a preferred embodiment of the present invention, the carbon nanotube film is prepared by floating catalytic chemical vapor deposition: after the catalyst is heated and sublimated, it is carried into the reactor by a protective gas, and then a mixed reaction gas of carbon source and hydrogen is introduced and heated to react. The resulting product is collected by a roller at the reactor outlet; the catalyst is preferably a mixture of ferrocene and sulfur.

[0035] Specific reaction conditions may include: a ferrocene to sulfur mass ratio of 20 to 200:1 in the mixture of ferrocene and sulfur, a carbon source flow rate of 5 to 25 sccm, a hydrogen flow rate of 3 to 10 sccm, and a reaction temperature of 1000 to 1100℃; the product is collected by a roller at the reactor outlet for 5 to 60 minutes.

[0036] According to a specific embodiment of the present invention, carbon nanotube films are prepared by floating catalytic chemical vapor deposition. The catalyst is a mixture of ferrocene and sulfur in a mass ratio of 20 to 200:1. After sublimation by heating, the catalyst is carried into the reactor by argon gas. The carbon source is 5 to 25 sccm of methane, with 3 to 10 sccm of hydrogen added as an etchant. The reaction temperature is 1000 to 1100°C. The product is collected by roller winding at the reactor outlet for 5 to 60 minutes.

[0037] According to the present invention, the electrodeposition of the conductive polymer on the surface of the carbon nanotube can be achieved by constructing a three-electrode system, wherein the three-electrode system uses an ultralong carbon nanotube as the working electrode, a platinum sheet as the counter electrode, and a saturated calomel electrode as the reference electrode.

[0038] The electrodeposition method used can be cyclic voltammetry or galvanostatic method. When using cyclic voltammetry, the scanning voltage range can be -0.7 to 1.3 V; preferably, the galvanostatic method is used, with a current density of 10 to 20 mA / cm².2 The polymerization time is 80-120 seconds.

[0039] According to some embodiments of the present invention, the electrolyte solution used for electrodeposition is an aqueous solution of SDS / LiClO4, an aqueous solution of SDS / C8H5NaO4, or an acetonitrile solution of TBAPF6, and the concentration of SDS in the aqueous solution of SDS / LiClO4 can be (20-50)×10⁻⁶. -3 The concentration of LiClO4 can be 0.1–0.3 mol / L; the concentration of SDS in the SDS / C8H5NaO4 aqueous solution can be 0.1–0.3 mol / L, and the concentration of C8H5NaO4 can be 0.05–0.2 mol / L; preferably, it is an acetonitrile solution of TBAPF6 with a TBAPF6 concentration of (20–40) × 10⁻⁶. -3 mol / L.

[0040] To form a conductive polymer, the electrolyte solution also contains monomers for forming the conductive polymer, wherein the monomer content is 0.05–0.2 mol / L.

[0041] The carbon nanotube / conductive polymer composite material of the present invention can be used to prepare electrodes, especially neural probe electrodes.

[0042] Specifically, the present invention provides a carbon nanotube composite neural probe electrode, the probe electrode comprising a probe electrode body and an electrode material loaded thereon, the electrode material being the aforementioned carbon nanotube / conductive polymer composite material.

[0043] According to the present invention, the probe electrode body can be a metal probe or a polymer tip, preferably a polymer tip with a diameter of 0.1 to 1 μm.

[0044] The polymer tip is preferably formed by hot drawing of a polymer preform. Preferably, the polymer is polyethylene terephthalate (PET) and / or polyurethane, more preferably PET.

[0045] According to a preferred embodiment of the present invention, the method for preparing the polymer tip includes: heating a polymer preform to melt at the tip, and then pulling it upwards over a distance of 1–20 mm at a speed of 1–10 mm / s. The size of the tip can be controlled by controlling the pulling distance and the pulling speed.

[0046] The present invention also provides a method for preparing the above-mentioned carbon nanotube composite neural probe electrode, comprising: bringing the probe electrode body close to the carbon nanotube / conductive polymer composite material, and pulling out a single ultra-long carbon nanotube or carbon nanotube bundle fiber by relying on van der Waals interaction to obtain the carbon nanotube composite neural probe electrode.

[0047] This invention provides a method for preparing a carbon nanotube composite neural probe electrode, starting with carbon nanotubes, such as... Figure 1 As shown, it includes:

[0048] Step S101: Obtain carbon nanotubes, wherein the carbon nanotubes are in the form of horizontally arrayed carbon nanotubes or carbon nanotube films.

[0049] Step S102: Electrodeposit the conductive polymer on the surface of the carbon nanotubes;

[0050] Step S103: The probe electrode body is brought close to the carbon nanotube / conductive polymer composite material, and a single ultra-long carbon nanotube or carbon nanotube bundle fiber is pulled out by van der Waals interaction to obtain a carbon nanotube composite neural probe electrode.

[0051] This invention provides a high-quality, selective neural interface composite electrode and its fabrication process for subcellular chronic neural detection and long-term stable signal recording.

[0052] The present invention will be further described below with reference to the embodiments, but the scope of the present invention is not limited to these embodiments.

[0053] Unless otherwise specified in the examples, all procedures were performed under standard conditions or conditions recommended by the manufacturer. Reagents or instruments whose manufacturers are not specified are all commercially available products.

[0054] Preparation Example 1: Controllable Preparation of Carbon Nanotube Thin Films

[0055] (1) A three-temperature zone horizontal tube furnace with a constant temperature section > 40cm is used as a reactor to carry out gas-solid reaction under normal pressure. A PTFE roller is placed at the outlet to receive the produced carbon nanotube membrane.

[0056] (2) Select ferrocene / sulfur (mass ratio 150:1) powder mixture as catalyst, grind and mix thoroughly, weigh 25mg into a small quartz boat and place it in the part of the inlet section of the reaction tube that is in contact with air. The quartz tube is wrapped with a heating belt and heated to 85℃ during the reaction stage to sublimate the catalyst and carry it into the reaction system by gas entrainment.

[0057] (3) Heat the reactor to the target reaction temperature of 1100℃ at a heating rate of 35℃ / min, and at the same time introduce argon gas at a flow rate of 100sccm as a carrier gas to exhaust the air in the reactor.

[0058] (4) During the reaction stage, the system temperature is maintained at 1100℃, while the carrier gas is replaced with argon at 1000 sccm, the carbon source for the reaction is methane at 20 sccm, and hydrogen at 5 sccm is passed through as an etchant to remove amorphous carbon structures and improve the quality of carbon nanotubes.

[0059] (5) When the reaction is stable, the cylindrical carbon nanotube aerogel generated by the reaction under the blowing of argon carrier gas is stably sprayed out from the outlet of the reaction tube and comes into contact with the polytetrafluoroethylene roller driven by the stepper motor to achieve winding and collection. The collection time is 50 min.

[0060] (6) After the reaction is complete, remove the roller and soak it in acetone to densify it. Use tweezers to directly peel off the carbon nanotube film on the roller to obtain a self-supporting carbon nanotube film structure with a carbon nanotube orientation degree of 40-50%.

[0061] Example 1: Deposition of PEDOT coating on carbon nanotube film surface by cyclic voltammetry

[0062] (1) The electrolyte solution used is 40×10 -3 An aqueous solution of 0.15 mol / L SDS and 0.15 mol / L LiClO4 was prepared, with 40 × 10⁻⁶ mol / L EDOT monomer added. -3 mol / L;

[0063] (2) The carbon nanotube film prepared in Example 1 was electropolymerized with EDOT in the above electrolyte solution using cyclic voltammetry, with a scanning voltage range of -0.7 to 1.3 V;

[0064] (3) A PEDOT coating was electrodeposited on the surface of the carbon nanotube film to obtain a carbon nanotube / PEDOT composite material with a PEDOT coverage of 85-90%.

[0065] Preparation Example 2: Controllable Preparation of Horizontally Arrayed Ultralong Carbon Nanotubes

[0066] (1) Place the silicon / silicon oxide growth substrate containing an ethanol solution of 0.03M FeCl3 catalyst in a quartz boat. The substrate surface is uniformly engraved with 5mm wide slits every 3cm. Place it in a tubular furnace reactor.

[0067] (2) A mixture of argon and hydrogen (Ar:H2 = 1:2, v / v) at 200 sccm is introduced into the reactor as a protective gas, and the temperature is raised. When the temperature reaches 900-1010℃, it is held at that temperature for 20 min. Then, the reaction stage begins, and a mixture of methane and hydrogen (H2:CH4 = 2:1, v / v) at 180 sccm is introduced to start the horizontal array ultra-long carbon nanotube preparation reaction, with a reaction time of 30 min.

[0068] (3) When the reaction is complete and the cooling stage begins, a mixture of argon and hydrogen (Ar:H2 = 1:2, v / v) is introduced at 200 sccm to prevent the carbon nanotubes from being ablated during the cooling process. After the temperature drops to room temperature, the sample is removed to obtain horizontally arrayed ultralong carbon nanotubes. The length of the ultralong carbon nanotubes is 60–100 mm and the diameter is 1.5–3.0 nm.

[0069] Example 2: Deposition of PEDOT coating on the surface of arrayed carbon nanotubes using a constant current method

[0070] (1) The electrolyte solution is an aqueous solution of 0.1 mol / L C8H5NaO4 and 0.15 mol / L SDS, with 0.1 mol / L of EDOT monomer added;

[0071] (2) The arrayed carbon nanotubes prepared in Example 2 were electropolymerized with EDOT in the above electrolyte solution using a constant current method at a current density of 4 mA / cm². 2 ;

[0072] (3) A carbon nanotube / PEDOT composite material was prepared by electrodepositing a PEDOT coating on the surface of the arrayed carbon nanotubes, with a PEDOT coverage of 80-85%.

[0073] Example 3: Deposition of PEDOT coating on the surface of arrayed carbon nanotubes using a constant current method

[0074] (1) The electrolyte solution used is 30×10 -3 Acetonitrile containing mol / L TBAPF6, with an added EDOT monomer amount of 0.1 mol / L;

[0075] (2) The arrayed carbon nanotubes prepared in Example 2 were electropolymerized with EDOT in the above electrolyte solution using a constant current method at a current density of 20 mA / cm². 2 ;

[0076] (3) A carbon nanotube / PEDOT composite material was prepared by electrodepositing a PEDOT coating on the surface of the arrayed carbon nanotubes, with a PEDOT coverage of 92-96%.

[0077] Example 4: Deposition of PEDOT coating on the surface of arrayed carbon nanotubes by cyclic voltammetry

[0078] (1) The electrolyte solution is an aqueous solution of 0.1 mol / L C8H5NaO4 and 0.18 mol / L SDS, with 0.1 mol / L of EDOT monomer added;

[0079] (2) The arrayed carbon nanotubes prepared in Example 2 were electropolymerized with EDOT in the above electrolyte solution using cyclic voltammetry, with a scanning voltage range of -0.9 to 1.3 V;

[0080] (3) A PEDOT coating was electrodeposited on the surface of the arrayed carbon nanotubes to prepare a carbon nanotube / PEDOT composite material with a PEDOT coverage of 85-90%.

[0081] Example 5: Fabrication of Nanoscale Carbon Nanotube Composite Probe Electrode

[0082] (1) Place a cylindrical PET preform with a diameter of 200μm close to the heating table and set the heating temperature to 250℃;

[0083] (2) After the PET preform is melted, it is pulled upwards by 15mm at a speed of 7mm / s to form a tip with a diameter of ~0.2μm;

[0084] (3) The tip of the above-mentioned material was brought close to the carbon nanotube / PEDOT composite material prepared in Example 3. A single ultra-long carbon nanotube / PEDOT composite fiber was pulled out by van der Waals interactions within a distance of ~10 nm to obtain a nanoscale diameter carbon nanotube composite probe electrode with a diameter of 3-6 nm. Its optical microscopy characterization results are as follows: Figure 2 As shown.

[0085] Example 6: Fabrication of submicron-scale carbon nanotube composite probe electrode

[0086] (1) Place a cylindrical PET preform with a diameter of 200μm close to the heating table and set the heating temperature to 250℃;

[0087] (2) After the PET preform is melted, it is pulled upwards by 10mm at a speed of 5mm / s to form a tip with a diameter of ~1μm;

[0088] (3) The above-mentioned tip is brought close to the carbon nanotube / PEDOT composite material prepared in Example 1, and the carbon nanotube bundle / PEDOT composite fiber is pulled out by van der Waals interaction within a distance of ~10nm to obtain a submicron diameter carbon nanotube composite probe electrode.

[0089] Example 7: Fabrication of submicron-scale carbon nanotube composite probe electrode

[0090] (1) Place a cylindrical PET preform with a diameter of 200μm close to the heating table and set the heating temperature to 250℃;

[0091] (2) After the PET preform is melted, it is pulled upwards by 4mm at a speed of 3mm / s to form a tip with a diameter of ~3μm;

[0092] The aforementioned tip is brought close to the carbon nanotube / PEDOT composite material prepared in Example 1, and the carbon nanotube bundle / PEDOT composite fiber is pulled out by van der Waals interactions within a distance of ~10 nm. Compared with Example 6, the carbon nanotube composite probe electrode prepared in this example has a larger diameter.

[0093] Example 8

[0094] (1) Place a PU preform with a diameter of 150μm close to the heating table and set the heating temperature to 120℃;

[0095] (2) After the PU preform is melted, it is pulled upwards by 10mm at a speed of 3mm / s to form a tip with a diameter of ~1.5μm, but the surface has more defects and depressions.

[0096] By bringing the aforementioned tip close to the carbon nanotube / PEDOT composite material prepared in Example 1, and pulling out the carbon nanotube bundle / PEDOT composite fiber within a distance of ~10 nm using van der Waals interactions, the prepared probe has an uneven diameter, with an average radial diameter of ~1 μm. However, due to numerous defects on the surface of the preform tip, the van der Waals forces between the preform and the carbon nanotube / PEDOT are weakened, resulting in a shorter probe length.

[0097] Test case

[0098] The probe electrodes prepared in Example 6 were used to record high-throughput neuronal activity in the full depth of the mouse brain. This enabled simultaneous monitoring of the activity of approximately 500 single neurons covering the full depth of the brain surface cortex, and is expected to achieve stable neural recordings for up to 6 months.

[0099] The probe electrode prepared in Example 7 was used to record the neuronal activity of mouse brains. It can simultaneously detect the activity of about 400 single neurons covering the entire depth of the brain surface cortex, and is expected to achieve stable neural recording for about 3 months, after which the signal intensity shows a significant attenuation trend.

[0100] The probe electrode prepared in Example 5 was used to record the activity of neurons in the mouse brain. It can simultaneously detect the activity of about 600 single neurons covering the entire depth of the brain surface cortex. It has a high response speed and sensitivity, but poor stability. It is only expected to achieve continuous detection for about 30 days, which is presumably related to its high aspect ratio structural features.

[0101] Compared to similar probe electrodes, this probe combines the mechanical advantages of carbon nanotubes with the electrical conductivity of polymers, enabling it to connect well with back-end electronic devices and achieve precise acquisition and transmission of neural signals. It demonstrates the probe's excellent performance tunability, biocompatibility, and long-term recording stability.

[0102] The various embodiments of the present invention have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments.

[0103] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

Claims

1. A carbon nanotube / conductive polymer composite material, characterized in that, The composite material consists of single carbon nanotubes and / or carbon nanotube bundles coated with conductive polymer, wherein the coverage of the conductive polymer is 80% or more, preferably 85% or more.

2. The carbon nanotube / conductive polymer composite material according to claim 1, wherein, The carbon nanotubes are high aspect ratio carbon nanotubes with an aspect ratio of 1000:1 or higher; The carbon nanotubes are preferably ultra-long carbon nanotubes, and more preferably, the length of the carbon nanotubes is 5 to 1000 mm, the diameter is 0.7 to 5 nm, and the diameter of the bundled fibers is 0.5 to 10 μm.

3. The carbon nanotube / conductive polymer composite material according to claim 1, wherein, The conductive polymer is selected from at least one of polyaniline, polypyrrole, PEDOT and PSS, preferably PEDOT.

4. A method for preparing the carbon nanotube / conductive polymer composite material according to any one of claims 1-3, comprising the following steps: (1) Obtain carbon nanotubes, wherein the carbon nanotubes are in the form of horizontally arrayed carbon nanotubes or carbon nanotube films. (2) Electrodeposit the conductive polymer on the surface of the carbon nanotube.

5. The method according to claim 4, wherein, In step (1), the horizontal array of carbon nanotubes is prepared on the substrate surface by chemical vapor deposition. Preferably, the substrate is any one of silicon, silicon / silicon oxide, highly oriented pyrolytic graphite, quartz and sapphire. More preferably, the substrate is a silicon / silicon oxide substrate with a number of slits with a width of 1 to 10 mm.

6. The method according to claim 5, wherein, The method for preparing the horizontal array carbon nanotubes includes: loading a catalyst onto a substrate and placing it in a reactor; reducing the catalyst by introducing a protective gas; then introducing a mixed reaction gas of carbon source and hydrogen and heating the reaction to prepare the horizontal array carbon nanotubes; the catalyst is preferably a chloride of at least one metal selected from Fe, Mo, Cu and Cr, and most preferably FeCl3 catalyst.

7. The method according to claim 6, wherein, The protective gas is argon or a mixture of argon and hydrogen, with a flow rate of 150–250 sccm; the flow rate of the mixed reaction gas of carbon source and hydrogen is 150–200 sccm; the reaction temperature is 900–1010℃, and the time is 20–60 min.

8. The method according to claim 4, wherein, In step (1), the carbon nanotube film is prepared by floating catalytic chemical vapor deposition: after the catalyst is heated and sublimated, it is carried into the reactor by a protective gas, and then a mixed reaction gas of carbon source and hydrogen is introduced and heated to react. The resulting product is collected by a roller at the reactor outlet; the catalyst is preferably a mixture of ferrocene and sulfur.

9. The method according to claim 8, wherein, The mass ratio of ferrocene to sulfur in the mixture of ferrocene and sulfur is 20–200:1, the carbon source flow rate is 5–25 sccm, the hydrogen flow rate is 3–10 sccm, and the reaction temperature is 1000–1100℃. The product is collected by a roller at the reactor outlet for 5–60 min.

10. The method according to claim 4, wherein, In step (2), the electrodeposition is achieved by constructing a three-electrode system, wherein the three-electrode system uses a carbon nanotube as the working electrode, a platinum sheet as the counter electrode, and a saturated calomel electrode as the reference electrode; the electrodeposition method is cyclic voltammetry or galvanostatic method, preferably using galvanostatic method, with a current density of 10-20 mA / cm². 2 The polymerization time is 80-120 seconds.

11. The method according to claim 10, wherein, The electrolyte solution used for electrodeposition is an aqueous solution of SDS / LiClO4, an aqueous solution of SDS / C8H5NaO4, or an acetonitrile solution of TBAPF6, preferably an acetonitrile solution of TBAPF6, with a TBAPF6 concentration of (20–40) × 10⁻⁶. -3 mol / L.

12. The method according to claim 11, wherein, The electrolyte solution also contains monomers of the conductive polymer, and the content of the monomers is 0.01 to 0.2 mol / L.

13. The use of the carbon nanotube / conductive polymer composite material according to any one of claims 1-3 in the preparation of electrodes.

14. A carbon nanotube composite neural probe electrode, the probe electrode comprising a probe electrode body and an electrode material loaded thereon, the electrode material being the carbon nanotube / conductive polymer composite material as described in any one of claims 1-3.

15. The carbon nanotube composite neural probe electrode according to claim 14, wherein, The probe electrode body is a metal probe or a polymer tip, preferably a polymer tip with a diameter of 0.1 to 1 μm.

16. The carbon nanotube composite neural probe electrode according to claim 15, wherein, The polymer tip is formed by hot drawing a polymer preform, and the polymer is preferably polyethylene terephthalate and / or polyurethane.

17. The carbon nanotube composite neural probe electrode according to claim 16, wherein, The method for preparing the polymer tip includes: heating the polymer preform to melt the end, and then pulling it upward. Preferably, the pulling distance is 1-20 mm and the pulling speed is 1-10 mm / s.

18. A method for preparing the carbon nanotube composite neural probe electrode according to any one of claims 14-17, comprising: By bringing the probe electrode body close to the carbon nanotube / conductive polymer composite material, a single carbon nanotube or carbon nanotube bundle fiber is pulled out by van der Waals interactions to obtain a carbon nanotube composite neural probe electrode.

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