High-density electroencephalogram electrode array and preparation method and application thereof

Abstract

The invention provides a high-density electroencephalogram electrode array and a preparation method and application thereof. The high-density electroencephalogram electrode array comprises a dielectric flexible substrate; the flexible electrode array is distributed on the surface of one side of the dielectric substrate layer, the flexible electrode array comprises a vertical carbon nanotube array and a carbon layer which are arranged in a stacked mode in the direction away from the dielectric substrate layer, and metal nanowires are distributed in array unit gaps of the vertical carbon nanotube array; and the hydrogel layer is positioned on the outer surface of the flexible electrode array. According to the high-density electroencephalogram electrode array, through multi-aspect collaborative design, on the premise that low interface impedance and high signal fidelity are maintained, the problems that traditional electroencephalogram equipment is insufficient in spatial resolution and poor in wearing comfort are solved, the electrode density and the quality of collected high-density electroencephalogram signals are improved, and the high-density electroencephalogram electrode array is suitable for popularization and application. The method provides a hardware basis for neural activity analysis, and has subversive potential in the field of high-performance brain-computer interfaces.

Description

Technical Field

[0001] The present invention belongs to the technical field of brain-computer interface, and specifically relates to a high-density EEG electrode array and a preparation method and application thereof. Background Art

[0002] EEG electrodes are the core components of the brain-computer interface system. Their main function is to attach to the surface of the scalp, accurately collect weak electrical signals generated by brain neuron activity, and transmit these signals to the EEG amplifier for further processing and analysis. At present, wet electrodes are the most widely used type of EEG acquisition electrodes, usually using silver / silver chloride (Ag / AgCl) as the main electrode material. During use, in order to reduce the impedance between the electrode and the scalp, a conductive medium needs to be applied between the two. However, this method of use also brings some inconveniences: the hair needs to be cleaned after use, which undoubtedly reduces the user experience. In addition, with the continuous increase in electrode density, the conductive medium easily causes series connection between adjacent electrodes, thereby hindering the realization of ultra-high-density EEG acquisition. Although the existing flexible electrodes eliminate the step of applying a conductive medium between the electrode and the scalp, thereby significantly improving the user experience, they face technical bottlenecks such as poor conductivity and severe attenuation of high-frequency signals in actual applications. In view of this, the development of new EEG electrodes is particularly critical and urgent for promoting the further development of brain-computer interface technology.

[0003] There are many studies on high-density EEG electrodes at present. For example, patent 202210909885.1 discloses a flexible high-density scalp EEG electrode and a preparation method thereof, which is to mix polydimethylsiloxane and tetrachloroauric acid aqueous solution evenly, keep it at 70-80°C for 1-1.5h, reduce tetrachloroauric acid to gold particles or gold trichloride, cool it to room temperature, add hybrids, and ultrasonicate to obtain sensitive materials. Patent 202210914567.4 discloses a non-invasive ultra-high-density EEG acquisition electrode, whose structure includes a hollow cylindrical electrode device and a needle-shaped electrode device. Patent 202010043816.8 provides a multi-layer flexible high-density EEG electrode and a preparation method thereof, wherein the multi-layer flexible high-density EEG electrode includes a plurality of stacked single-layer electrodes and an isolation layer covering the upper surface of the uppermost single-layer electrode. However, the above method has problems such as density-resolution contradiction and poor quality of high-density EEG signals.

[0004] Therefore, how to break through the physical limitations of traditional high-density EEG and improve the quality of collected high-density EEG signals while maintaining the performance of the electrode-scalp interface is a technical problem that needs to be solved urgently. Summary of the invention

[0005] Aiming at the deficiencies of the prior art, the purpose of the present invention is to provide a high-density electroencephalogram (EEG) electrode array, a preparation method thereof, and an application thereof. The high-density EEG electrode array provided by the present invention is designed through multi-faceted coordination. On the premise of maintaining low interface impedance and high signal fidelity, it not only solves the problems of insufficient spatial resolution and poor wearing comfort of traditional EEG devices, but also improves the electrode density and the quality of the collected high-density EEG signals, and is expected to bring the EEG spatial sampling rate into the sub-millimeter level.

[0006] To achieve the purpose of this invention, the following technical solutions are adopted:

[0007] In the first aspect, the present invention provides a high-density EEG electrode array, which includes:

[0008] A dielectric flexible substrate.

[0009] A flexible electrode array, which is distributed on one surface of the dielectric substrate layer, and the flexible electrode array includes a vertically stacked carbon nanotube array and a carbon layer along the direction away from the dielectric substrate layer, and metal nanowires are distributed in the array unit gaps of the vertically stacked carbon nanotube array.

[0010] A hydrogel layer, which is located on the outer surface of the flexible electrode array.

[0011] The present invention consists of a flexible electrode array composed of a carbon layer / silver nanowire three-dimensional conductive network enhanced by vertically stacked carbon nanotubes, and realizes a sub-millimeter electrode pitch through a dielectric flexible substrate. The hydrogel layer has dynamic adhesion and long-term moisturizing properties. Therefore, through multi-faceted coordination design, on the premise of maintaining low interface impedance and high signal fidelity, this high-density EEG electrode array not only solves the problems of insufficient spatial resolution and poor wearing comfort of traditional EEG devices, but also improves the electrode density and the quality of the collected high-density EEG signals. Its impedance is significantly reduced by 50% and the channel crosstalk is reduced to -65 dB, which provides a hardware basis for analyzing neural activities and has subversive potential in the field of high-performance brain-computer interfaces.

[0012] In the present invention, the vertically stacked carbon nanotubes cooperate with the carbon layer and silver nanowires to form a flexible electrode array, which can further improve the electrode conductivity, mechanical flexibility and interface stability.

[0013] In the present invention, metal nanowires are distributed in the array unit gaps of the vertically stacked carbon nanotube array, which helps to form a continuous conductive path.

[0014] Preferably, the dielectric flexible substrate includes a polymer film and an inorganic film stacked along the direction close to the flexible electrode array.

[0015] Preferably, the material of the polymer film includes any one or a combination of at least two of polydimethylsiloxane, polyimide, polystyrene, or polyethylene terephthalate.

[0016] Preferably, the material of the inorganic film includes any one or a combination of at least two of boron nitride, alumina, or silicon carbide.

[0017] Preferably, the thickness of the inorganic film is 1 - 3 μm, and for example, it can be 1 μm, 1.5 μm, 2 μm, 2.5 μm, or 3 μm, etc.

[0018] In the present invention, an inorganic film with an appropriate thickness can significantly reduce the dielectric loss of the polymer film.

[0019] Preferably, the density of the vertical carbon nanotube array is 5×10 9 -5×10 11 roots / cm 2 and for example, it can be 5×10 9 roots / cm 2 、1×10 10 roots / cm 2 、5×10 10 roots / cm 2 、1×10 11 roots / cm 2 or 5×10 11 roots / cm 2 etc.

[0020] In the present invention, a vertical carbon nanotube array with an appropriate density helps to reduce the surface resistance, improve the mechanical durability of the electrode, and enhance the uniformity of the electric field distribution to suppress signal attenuation.

[0021] Preferably, the height of the vertical carbon nanotube array is 4 - 8 μm, and for example, it can be 4 μm, 5 μm, 6 μm, 7 μm, or 8 μm, etc.

[0022] Preferably, the carbon layer includes a graphene layer. Exemplarily, for example, it is a single-layer graphene layer.

[0023] Preferably, the thickness of the carbon layer is 0.3 - 1.2 nm, and for example, it can be 0.3 nm, 0.6 nm, 0.9 nm, 1 nm, or 1.2 nm, etc.

[0024] Preferably, the material of the metal nanowire includes any one or a combination of at least two of silver, copper, or platinum.

[0025] Preferably, the hydrogel layer is a self-adhesive hydrogel layer.

[0026] In the present invention, the self-adhesive hydrogel layer has the characteristics of dynamic adhesion and long-term moisturization.

[0027] Preferably, the hydrogel layer contains polyethylene glycol diacrylate microspheres.

[0028] In the present invention, the introduction of polyethylene glycol diacrylate microspheres helps to balance the long-term wearing stability and the painless removal experience. Preferably, the average particle size of the polyethylene glycol diacrylate microspheres is 1-3 μm, for example, it can be 1 μm, 1.5 μm, 2 μm, 2.5 μm or 3 μm, etc.

[0029] Preferably, the distribution density of the polyethylene glycol diacrylate microspheres is 1×10 4 -1×10 5 pieces / cm 2 , for example, it can be 1×10 4 pieces / cm 2 , 3×10 4 pieces / cm 2 , 5×10 4 pieces / cm 2 , 7×10 4 pieces / cm 2 or 1×10 5 pieces / cm 2 etc.

[0030] In the present invention, an appropriate distribution density helps to balance the adhesion strength and the ion diffusion efficiency, ensuring the conductivity while avoiding the cracking of the hydrogel layer caused by local stress concentration.

[0031] Preferably, the hydrogel layer has a gecko foot-like structure.

[0032] In the present invention, the hydrogel layer has a gecko foot-like structure. On the one hand, it can enhance the adhesion between the electrode and the scalp, improving the wearing comfort. On the other hand, it can be reused, reducing the damage to the skin.

[0033] Preferably, the peel strength of the self-adhesive hydrogel layer is 0.5-1.2 N / cm 2 , for example, it can be 0.5 N / cm 2 , 0.6 N / cm 2 , 0.7 N / cm 2 , 0.8 N / cm 2 , 0.9 N / cm 2 , 1 N / cm 2 , 1.1 N / cm 2 or 1.2 N / cm 2 etc.

[0034] In the present invention, an appropriate peel strength helps to ensure stable contact between the electrode and the scalp during measurement, can effectively collect EEG signals, reduce signal interference and distortion caused by electrode loosening or displacement, and ensure signal quality. Moreover, an appropriate peel strength can prevent skin damage when the electrode is removed. If the peel strength is too large, it will be difficult to remove the electrode and it is easy to pull the skin. If the peel strength is too small, the electrode is likely to fall off and signals cannot be collected normally.

[0035] Preferably, the electrode distribution density of the high-density EEG electrode array ≥ 20 electrodes / cm 2 , for example, it can be 20 electrodes / cm 2 , 40 electrodes / cm 2 , 60 electrodes / cm 2 , 70 electrodes / cm 2 , 80 electrodes / cm 2 , 90 electrodes / cm 2 or 100 electrodes / cm 2 etc.

[0036] Preferably, in the EEG electrode array, the distance between electrodes ≤ 2.5 mm, for example, it can be 2.5 mm, 2.1 mm, 2 mm, 1.5 mm, 1 mm, 0.5 mm, 0.4 mm, 0.3 mm, 0.2 mm or 0.1 mm etc.

[0037] In a second aspect, the present invention provides a method for preparing a high-density EEG electrode array as described in the first aspect, and the preparation method includes the following steps:

[0038] (a) Prepare a dielectric flexible substrate.

[0039] Deposit a carbon layer and a vertical carbon nanotube array on a metal foil in sequence, and then deposit metal nanowires in the array unit gaps of the vertical carbon nanotube array to obtain a transferable electrode array.

[0040] (b) Transfer the transferable electrode array onto one side surface of the dielectric flexible substrate, and then cure it so that the vertical carbon nanotube array contacts the dielectric flexible substrate, and then remove the metal foil to expose the carbon layer.

[0041] (c) Coat a hydrogel precursor solution on the outer surface of the carbon layer and cure it to form a hydrogel layer.

[0042] Preferably, the method for preparing the dielectric flexible substrate in step (a) includes:

[0043] Deposit a polymer film and an inorganic film on a hard substrate in sequence.

[0044] Preferably, the hard substrate is a silicon wafer.

[0045] It should be noted that the subsequent silicon wafers can be removed by wet etching.

[0046] Preferably, the method for preparing the polymer film includes:

[0047] Mix the polymer prepolymer and the curing agent, then coat it on the surface of the silicon wafer and cure to form a polymer film.

[0048] Preferably, the curing agent includes benzoyl peroxide.

[0049] Preferably, the mass ratio of the polymer prepolymer to the curing agent is (8 - 12):1, for example, it can be 8:1, 9:1, 10:1, 11:1 or 12:1, etc.

[0050] Preferably, the curing temperature is 60°C, 70°C, 80°C, 90°C or 100°C, etc.

[0051] Preferably, the curing time is 1 - 3 h, for example, it can be 1 h, 2 h or 3 h, etc.

[0052] Preferably, before preparing the inorganic film on the polymer film, the surface of the polymer film is first subjected to plasma treatment.

[0053] In the present invention, the purpose of plasma treating the surface of the polymer film is to ensure the long-term electrical stability of the electrode under dynamic deformation.

[0054] Preferably, the method for preparing the inorganic film includes chemical vapor deposition.

[0055] Preferably, in the chemical vapor deposition method, the following parameters are included:

[0056] The reactant gases include a boron source and a nitrogen source with a flow ratio of 1:(2 - 6) (for example, it can be 1:2, 1:3, 1:4, 1:5 or 1:6, etc.), the growth temperature is 350 - 450°C (for example, it can be 350°C, 400°C or 450°C, etc.), the growth time is 1 - 3 h (for example, it can be 1 h, 1.5 h, 2 h, 2.5 h or 3 h, etc.), and the growth pressure is 2 - 8 Pa (for example, it can be 2 Pa, 4 Pa, 6 Pa or 8 Pa, etc.).

[0057] Preferably, the boron source includes B2H6.

[0058] Preferably, the nitrogen source includes NH3.

[0059] Preferably, the method for preparing the carbon layer in step (a) includes chemical vapor deposition.

[0060] Preferably, the method for preparing the vertical carbon nanotube array in step (a) includes the following steps:

[0061] First, a metal catalyst layer is prepared on the carbon layer, and then the growth of the vertical carbon nanotube array is carried out.

[0062] In the present invention, the purpose of preparing a metal catalyst layer is to reduce the energy required for the decomposition of the carbon source, improve the decomposition efficiency of the carbon source, and also guide the growth sites and growth directions of the carbon nanotubes to form vertically aligned carbon nanotubes with highly consistent orientation.

[0063] Preferably, the thickness of the metal catalyst layer is 3 - 8 nm, such as 3 nm, 4 nm, 5 nm, 6 nm, 7 nm or 8 nm, etc.

[0064] Preferably, the growth method of the vertical carbon nanotube array includes chemical vapor deposition. In the chemical vapor deposition method, the reactant gases include a gaseous carbon source and hydrogen with a flow ratio of 1:(8 - 12) (such as 1:8, 1:9, 1:10, 1:11 or 1:12, etc.).

[0065] Preferably, the gaseous carbon source includes C2H4.

[0066] Preferably, in the chemical vapor deposition method, the deposition temperature is 600 - 700 °C, such as 600 °C, 650 °C or 700 °C, etc.

[0067] Preferably, the deposition method of the metal nanowires in step (a) includes:

[0068] The semi-finished product after preparing the vertical carbon nanotube array in step (a) is immersed in the metal nanowire dispersion liquid, subjected to electrophoretic deposition, and then annealed.

[0069] Preferably, the concentration of the metal nanowire dispersion liquid is 0.4 - 0.8 wt%, such as 0.4 wt%, 0.5 wt%, 0.6 wt%, 0.7 wt% or 0.8 wt%, etc.

[0070] Preferably, during the electrophoretic deposition process, the electric field strength is 10 - 20 V / cm, such as 10 V / cm, 12 V / cm, 14 V / cm, 16 V / cm, 18 V / cm or 20 V / cm, etc.

[0071] Preferably, the time of the electrophoretic deposition is 30 - 50 min, such as 30 min, 40 min or 50 min, etc.

[0072] Preferably, the annealing temperature is 180 - 220 °C, such as 180 °C, 190 °C, 200 °C, 210 °C or 220 °C, etc.

[0073] Preferably, the annealing time is 1 - 3 h, such as 1 h, 2 h or 3 h, etc.

[0074] Preferably, before transferring the electrode array to be transferred in step (b), a fractal geometric electrode arrangement is first performed using a 5th-order space-filling Hilbert curve algorithm.

[0075] In the present invention, a fractal geometric electrode arrangement is performed using a 5th-order space-filling Hilbert curve algorithm, which can achieve a high-density integration of 512 channels for the electrode array, and the number of wire crossing points is reduced by 60%-80%, which helps to reduce signal interference and improve the service life of the electrodes.

[0076] It should be noted that the Hilbert curve is a fractal curve and can be generated using MATLAB.

[0077] Preferably, the transfer method described in step (b) includes nanoimprint lithography.

[0078] In the present invention, nanoimprint lithography is used to transfer the flexible electrode array, and its patterning accuracy reaches ±0.5 μm.

[0079] Preferably, in the nanoimprint lithography method, the line width of the imprint template ≤ 500 nm, for example, it can be 500 nm, 400 nm, 300 nm or 200 nm, etc.

[0080] In the present invention, by limiting the line width of the imprint template ≤ 500 nm, a leapfrog improvement in electrode density from 256 channels (5 mm pitch) to 512 channels can be achieved while ensuring signal quality.

[0081] Preferably, before coating the hydrogel precursor solution on the outer surface of the carbon layer, a prepolymer solution is first coated and then cured.

[0082] In the present invention, the purpose of pre-coating the prepolymer solution is to form a uniform and dense unmodified hydrogel layer on the electrode surface, realizing a low-impedance interface coupling between the electrode and biological tissue, and at the same time ensuring the continuity of the ion migration channels.

[0083] Preferably, the prepolymer solution includes acrylamide, sodium alginate and a solvent. The present invention does not limit the mass ratio of acrylamide to sodium alginate. Exemplarily, for example, it can be 1:1, etc.

[0084] Preferably, the solvent is water.

[0085] Preferably, the preparation method includes the following steps:

[0086] (1) Mix the polymer prepolymer and the curing agent in a mass ratio of (8-12):1, then coat it on the surface of the silicon wafer, and cure it at 60-100 °C for 1-3 h to form a polymer film.

[0087] The polymer film is subjected to oxygen plasma treatment, and then a boron nitride film is deposited on the surface of the polymer film by chemical vapor deposition to obtain a dielectric flexible substrate; in the chemical vapor deposition method, the following parameters are included:

[0088] The reactant gases include a boron source and a nitrogen source with a flow ratio of 1:(2 - 6), the growth temperature is 350 - 450 °C, the growth time is 1 - 3 h, and the growth pressure is 2 - 8 Pa.

[0089] (2) A carbon layer is prepared on the metal foil, and then a metal catalyst layer with a thickness of 3 - 8 nm is deposited. Subsequently, vertically aligned carbon nanotube arrays with a height of 4 - 8 μm are grown on the metal catalyst layer by chemical vapor deposition. Finally, the obtained semi-finished product is immersed in a metal nanowire dispersion solution with a concentration of 0.4 - 0.8 wt%, and an electric field of 10 - 20 V / cm is applied for 30 - 50 min for electrophoretic deposition to fill the metal nanowires in the array units of the vertically aligned carbon nanotube arrays. After the deposition, annealing is carried out at 180 - 220 °C for 1 - 3 h; in the chemical vapor deposition method, the reactant gases include a gaseous carbon source and hydrogen with a flow ratio of 1:(8 - 12), and the deposition temperature is 600 - 700 °C.

[0090] (3) The fractal geometric electrode arrangement is carried out by using the 5th-order space-filling Hilbert curve algorithm. Then, a photoresist is spin-coated on the boron nitride film surface of the dielectric flexible substrate, and the flexible electrode array obtained in step (2) is transferred by using a nanoimprint machine under a pressure of 0.4 - 0.8 MPa (for example, it can be 0.4 MPa, 0.5 MPa, 0.6 MPa, 0.7 MPa, or 0.8 MPa, etc.). Then, it is cured so that the vertically aligned carbon nanotube arrays contact the dielectric flexible substrate. Subsequently, the metal nanowires are selectively sintered by laser, and the metal foil is removed by acid etching to expose the carbon layer.

[0091] (4) Prepare a prepolymer solution, and the prepolymer solution includes acrylamide, sodium alginate, and a solvent;

[0092] The prepolymer solution is coated on the surface of the carbon layer in step (3) and subjected to the first curing. Then, a suspension solution of polyethylene glycol diacrylate microspheres is coated and subjected to the second curing to form a hydrogel layer; wherein, the concentration of the suspension solution containing polyethylene glycol diacrylate microspheres is 8 - 12 wt% (for example, it can be 8 wt%, 9 wt%, 10 wt%, 11 wt%, or 12 wt%, etc.).

[0093] It should be noted that the purpose of selectively sintering the metal nanowires by laser is to optimize the electrical and mechanical properties of the silver nanowire conductive network through precise energy input.

[0094] In a third aspect, the present invention provides an application of the high-density electroencephalogram electrode array as described in the first aspect, and the high-density electroencephalogram electrode array is applied to the field of brain-computer interfaces.

[0095] In the high-density electroencephalogram electrode array designed by the present invention, the hydrogel layer contacts the scalp, and the dielectric flexible substrate is connected to the electroencephalogram discharger through a wire to realize the acquisition of electroencephalogram signals.

[0096] The numerical ranges described in the present invention not only include the above-listed point values, but also include any point values between the above numerical ranges that are not listed. Due to space limitations and for the sake of brevity, the present invention does not exhaustively list the specific point values included in the range.

[0097] Compared with the prior art, the present invention has the following beneficial effects:

[0098] (1) The flexible electrode array of the present invention is composed of a carbon layer / silver nanowire three-dimensional conductive network enhanced by vertical carbon nanotubes, and the sub-millimeter electrode spacing is realized through the dielectric flexible substrate. The hydrogel layer has dynamic adhesion and long-term moisturizing characteristics. Therefore, through multi-faceted collaborative design, the high-density electroencephalogram electrode array not only solves the problems of insufficient spatial resolution and poor wearing comfort of traditional electroencephalogram devices while maintaining low interface impedance and high signal fidelity, but also improves the electrode density and the quality of the high-density electroencephalogram signals collected, which provides a hardware basis for the analysis of neural activities and has disruptive potential in the field of high-performance brain-computer interfaces.

[0099] (2) In the high-density electroencephalogram electrode array provided by the present invention, the impedance is lower than 2 kΩ at the spacing between adjacent electrodes, the noise level is less than 0.3 μVrms, it supports 72-hour continuous monitoring, and the spatial resolution is more than 3 times higher than that of traditional Ag / AgCl electrodes. Moreover, compared with traditional Ag / AgCl electrodes, its impedance is significantly reduced by 50% and the channel crosstalk is reduced to -65 dB.

[0100] (3) The high-density electroencephalogram electrode array provided by the present invention can achieve 512-channel high-density integration. Compared with the traditional rectangular array, the number of wire crossing points is reduced, which helps to reduce signal interference and improve the service life of the electrodes. BRIEF DESCRIPTION OF THE DRAWINGS

[0101] Figure 1 It is the process flow chart provided in Embodiment 1 of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0102] The technical solutions of the present invention will be further described below through specific embodiments. Those skilled in the art should understand that the embodiments are only for helping to understand the present invention and should not be regarded as specific limitations to the present invention.

[0103] Embodiment 1

[0104] This embodiment provides a high-density electroencephalogram (EEG) electrode array, which includes:

[0105] A dielectric flexible substrate.

[0106] A flexible electrode array, which is distributed on one surface of the dielectric substrate layer, and the flexible electrode array includes a vertically stacked carbon nanotube array and a single-layer graphene layer along the direction away from the dielectric substrate layer. Silver nanowires are distributed in the array unit gaps of the vertically stacked carbon nanotube array.

[0107] A self-adhesive hydrogel layer, which is located on the outer surface of the flexible electrode array. The self-adhesive hydrogel layer contains polyethylene glycol diacrylate microspheres, and the average particle size of the polyethylene glycol diacrylate microspheres is 2 μm, and the distribution density is 5×10 4 pcs / cm 2 ; the self-adhesive hydrogel layer has a biomimetic gecko foot structure.

[0108] Among them, the dielectric flexible substrate includes a stacked polydimethylsiloxane film and a boron nitride film along the direction close to the flexible electrode array. The thickness of the boron nitride film is 1.8 μm; the density of the vertically stacked carbon nanotube array is 5×10 10 pcs / cm 2 , and the height of the vertically stacked carbon nanotube array is 6 μm.

[0109] This embodiment also provides a preparation method for the above high-density EEG electrode array. The process flow chart is as Figure 1 shown. The preparation method includes the following steps:

[0110] (1) Prepare the dielectric flexible substrate: Mix polydimethylsiloxane prepolymer and benzoyl peroxide in a mass ratio of 10:1, then spin-coat it on the surface of a silicon wafer, and cure it at 80 °C for 2 h to form a polydimethylsiloxane film.

[0111] Perform oxygen plasma treatment on the polydimethylsiloxane film, and then deposit a boron nitride film on the surface of the polydimethylsiloxane film by chemical vapor deposition to obtain the dielectric flexible substrate; in the chemical vapor deposition method, the following parameters are included:

[0112] The reactant gases include B2H6 and NH3 with a flow ratio of 1:4, the growth temperature is 400 °C, the growth time is 2 h, and the growth pressure is 5 Pa.

[0113] (2) The chemical vapor deposition method is adopted to grow a single-layer graphene layer on a copper foil, and then a nickel catalyst layer with a thickness of 5 nm is sputter-deposited by magnetron sputtering. Subsequently, a vertical carbon nanotube array with a height of 6 μm is grown on the nickel catalyst layer by chemical vapor deposition. Finally, the obtained semi-finished product is immersed in a silver nanowire ethanol dispersion solution with a concentration of 0.6 wt%, and an electric field of 15 V / cm is applied for 40 min for electrophoretic deposition to fill the silver nanowires in the array units of the vertical carbon nanotube array. After the deposition, vacuum annealing is carried out at 200 °C for 2 h. In the chemical vapor deposition method, the reactant gases include C2H4 and hydrogen with a flow ratio of 1:10, and the deposition temperature is 650 °C.

[0114] (3) Use MATLAB to generate a 5th-order space-filling algorithm for Hilbert curve and perform fractal geometric electrode arrangement, with the spacing between adjacent electrodes less than 2.1 mm.

[0115] Spin-coat SU-8 2002 photoresist on the surface of the boron nitride film of the dielectric flexible substrate, and use a nanoimprinting machine (the line width of the imprinting template ≤ 500 nm) to transfer the flexible electrode array obtained in step (2) under a pressure of 0.6 MPa. Then, ultraviolet light with a wavelength of 365 nm is used for curing for 90 s to make the vertical carbon nanotube array contact the dielectric flexible substrate. Subsequently, femtosecond laser (wavelength 1030 nm, pulse energy 12 μJ, repetition frequency 100 kHz) is used for selective sintering of silver nanowires, and nitric acid with a concentration of 5 wt% is used to remove the copper foil to expose the single-layer graphene layer.

[0116] (4) Prepare a prepolymer solution, which includes acrylamide, sodium alginate and water, and the mass ratio of acrylamide to sodium alginate is 1:1.

[0117] Spray the prepolymer solution on the surface of the single-layer graphene layer in step (3) to form a wet film with a thickness of 250 μm, and perform the first ultraviolet light curing (wavelength 365 nm, intensity 15 mW / cm 2 ) in a nitrogen atmosphere for 120 s. Then, spray a suspension containing polyethylene glycol diacrylate microspheres and perform the second ultraviolet light curing (wavelength 365 nm, intensity 15 mW / cm 2 ) to form a hydrogel layer. Among them, the concentration of the suspension containing polyethylene glycol diacrylate microspheres is 10 wt%.

[0118] Using the parallel plate capacitance method, the dielectric constant of the dielectric flexible substrate provided in this embodiment is measured to be 2.2, and using a universal material testing machine, the tensile rate of the dielectric flexible substrate provided in this embodiment is measured to be 220%.

[0119] Evaluated by the four-probe method and dynamic bending test, the sheet resistance of the flexible electrode array prepared in step (2) of this example was measured to be 0.45 Ω / sq, and the resistance change rate after 5000 bends was 4.3%.

[0120] The 90° peel test was carried out according to the ASTM D3330 standard, and the peel strength of the hydrogel layer was measured to be 0.68 N / cm 2 , and it remained 0.52 N / cm after 72 h 2 , and the conductivity was measured to be 3.2 S / m by the four-electrode alternating current impedance method.

[0121] Example 2

[0122] This example provides a high-density electroencephalogram electrode array, and the high-density electroencephalogram electrode array includes:

[0123] A dielectric flexible substrate.

[0124] A flexible electrode array, the flexible electrode array is distributed on one side surface of the dielectric substrate layer, and the flexible electrode array includes a vertically stacked carbon nanotube array and a single-layer graphene layer along the direction away from the dielectric substrate layer, and silver nanowires are distributed in the array unit gaps of the vertically stacked carbon nanotube array.

[0125] A self-adhesive hydrogel layer, the self-adhesive hydrogel layer is located on the outer surface of the flexible electrode array, the self-adhesive hydrogel layer contains polyethylene glycol diacrylate microspheres, the average particle size of the polyethylene glycol diacrylate microspheres is 1 μm, and the distribution density is 1×10 5 pieces / cm 2 ; the self-adhesive hydrogel layer is a biomimetic gecko foot structure, and its peel strength is 0.52 N / cm 2 .

[0126] Among them, the dielectric flexible substrate includes a stacked polydimethylsiloxane film and an alumina film along the direction close to the flexible electrode array, and the thickness of the alumina film is 1 μm; the density of the vertically stacked carbon nanotube array is 5×10 9 roots / cm 2 , and the height of the vertically stacked carbon nanotube array is 4 μm.

[0127] This example also provides a preparation method for the above high-density electroencephalogram electrode array, and the preparation method includes the following steps:

[0128] (1) Mix the polydimethylsiloxane prepolymer and benzoyl peroxide in a mass ratio of 8:1, then spin-coat it on the surface of the silicon wafer, and cure it at 60 °C for 3 h to form a polydimethylsiloxane film.

[0129] The polydimethylsiloxane film is subjected to oxygen plasma treatment, and then an alumina film is deposited on the surface of the polydimethylsiloxane film by chemical vapor deposition to obtain a dielectric flexible substrate; in the chemical vapor deposition method, the following parameters are included:

[0130] The reactant gases include B2H6 and NH3 with a flow ratio of 1:2, the growth temperature is 350 °C, the growth time is 3 h, and the growth pressure is 2 Pa.

[0131] (2) Using chemical vapor deposition, a single-layer graphene layer is grown on a copper foil, and then a nickel catalyst layer with a thickness of 3 nm is sputter-deposited by magnetron sputtering. Subsequently, a vertical carbon nanotube array with a height of 4 μm is grown on the nickel catalyst layer by chemical vapor deposition. Finally, the obtained semi-finished product is immersed in a silver nanowire ethanol dispersion with a concentration of 0.4 wt%, and an electric field of 10 V / cm is applied for 50 min for electrophoretic deposition to fill the silver nanowires in the array units of the vertical carbon nanotube array. After the deposition, vacuum annealing is carried out at 180 °C for 3 h; in the chemical vapor deposition method, the reactant gases include C2H4 and hydrogen with a flow ratio of 1:8, and the deposition temperature is 600 °C.

[0132] (3) Use MATLAB to generate a 5th-order space-filling algorithm for the Hilbert curve for fractal geometric electrode arrangement, and the distance between adjacent electrodes is less than 2.1 mm.

[0133] SU-8 2002 photoresist is spin-coated on the alumina film surface of the dielectric flexible substrate, and a flexible electrode array obtained in step (2) is transferred at a pressure of 0.4 MPa using a nanoimprinting machine (the line width of the imprinting template ≤ 500 nm). Then, ultraviolet light with a wavelength of 365 nm is used for curing for 90 s, so that the vertical carbon nanotube array contacts the dielectric flexible substrate. Subsequently, femtosecond laser (wavelength 1030 nm, pulse energy 12 μJ, repetition frequency 100 kHz) is used to selectively sinter the silver nanowires, and the copper foil is removed using nitric acid with a concentration of 5 wt% to expose the single-layer graphene layer.

[0134] (4) Prepare a prepolymer solution, which includes acrylamide, sodium alginate, and water, where the mass ratio of acrylamide to sodium alginate is 1:1;

[0135] The prepolymer solution is sprayed on the surface of the single-layer graphene layer in step (3) to form a wet film with a thickness of 250 μm, and the first ultraviolet light curing (wavelength 365 nm, intensity 15 mW / cm 2 ) is carried out under a nitrogen atmosphere for 120 s. Then, a suspension containing polyethylene glycol diacrylate microspheres is sprayed, and the second ultraviolet light curing (wavelength 365 nm, intensity 15 mW / cm 2), forming a hydrogel layer; wherein, the concentration of the suspension containing polyethylene glycol diacrylate microspheres is 8 wt%.

[0136] Example 3

[0137] This example provides a high-density electroencephalogram electrode array, and the high-density electroencephalogram electrode array includes:

[0138] A dielectric flexible substrate.

[0139] A flexible electrode array, the flexible electrode array is distributed on one surface of the dielectric substrate layer, and the flexible electrode array includes a vertically stacked carbon nanotube array and a single-layer graphene layer along the direction away from the dielectric substrate layer, and silver nanowires are distributed in the array unit gaps of the vertically stacked carbon nanotube array.

[0140] A self-adhesive hydrogel layer, the self-adhesive hydrogel layer is located on the outer surface of the flexible electrode array, the self-adhesive hydrogel layer contains polyethylene glycol diacrylate microspheres, the average particle size of the polyethylene glycol diacrylate microspheres is 3 μm, and the distribution density is 1×10 4 pieces / cm 2 ; the self-adhesive hydrogel layer has a bionic gecko foot structure, and its peel strength is 0.52 N / cm 2 .

[0141] Among them, the dielectric flexible substrate includes a stacked polydimethylsiloxane film and a silicon carbide film along the direction close to the flexible electrode array, and the thickness of the silicon carbide film is 3 μm; the density of the vertically stacked carbon nanotube array is 5×10 11 roots / cm 2 , and the height of the vertically stacked carbon nanotube array is 8 μm.

[0142] This example also provides a preparation method of the above high-density electroencephalogram electrode array, and the preparation method includes the following steps:

[0143] (1) Mix polydimethylsiloxane prepolymer and benzoyl peroxide according to a mass ratio of 12:1, then spin-coat on the surface of a silicon wafer, and cure at 100 °C for 1 h to form a polydimethylsiloxane film.

[0144] Perform oxygen plasma treatment on the polydimethylsiloxane film, and then deposit a silicon carbide film on the surface of the polydimethylsiloxane film by chemical vapor deposition to obtain a dielectric flexible substrate; in the chemical vapor deposition method, the following parameters are included:

[0145] The reactant gases include B2H6 and NH3 with a flow ratio of 1:4, the growth temperature is 450 °C, the growth time is 1 h, and the growth pressure is 8 Pa.

[0146] (2) A single-layer graphene layer is grown on a copper foil by chemical vapor deposition. Then, a nickel catalyst layer with a thickness of 8 nm is sputter-deposited by magnetron sputtering. Subsequently, a vertical carbon nanotube array with a height of 8 μm is grown on the nickel catalyst layer by chemical vapor deposition. Finally, the obtained semi-finished product is immersed in a silver nanowire ethanol dispersion with a concentration of 0.8 wt%, and an electric field of 20 V / cm is applied for 30 min for electrophoretic deposition to fill the silver nanowires in the array units of the vertical carbon nanotube array. After the deposition, vacuum annealing is carried out at 220 °C for 1 h. In the chemical vapor deposition method, the reactant gases include C2H4 and hydrogen with a flow ratio of 1:12, and the deposition temperature is 700 °C.

[0147] (3) Use MATLAB to generate a 5th-order space-filling algorithm for the Hilbert curve for fractal geometric electrode arrangement, and the distance between adjacent electrodes is less than 2.1 mm.

[0148] Spin-coat SU-8 2002 photoresist on the surface of the silicon carbide film of the dielectric flexible substrate, and use a nanoimprinting machine (the line width of the imprinting template ≤ 500 nm) to transfer the flexible electrode array obtained in step (2) under a pressure of 0.8 MPa. Then, ultraviolet light with a wavelength of 365 nm is used for curing for 90 s to make the vertical carbon nanotube array contact the dielectric flexible substrate. Subsequently, femtosecond laser (wavelength 1030 nm, pulse energy 12 μJ, repetition frequency 100 kHz) is used to selectively sinter the silver nanowires, and nitric acid with a concentration of 5 wt% is used to remove the copper foil to expose the single-layer graphene layer.

[0149] (4) Prepare a prepolymer solution, which includes acrylamide, sodium alginate and water, and the mass ratio of acrylamide to sodium alginate is 1:1.

[0150] Spray the prepolymer solution on the surface of the single-layer graphene layer in step (3) to form a wet film with a thickness of 250 μm, and carry out the first ultraviolet light curing (wavelength 365 nm, intensity 15 mW / cm 2 ) in a nitrogen atmosphere for 120 s. Then, spray a suspension containing polyethylene glycol diacrylate microspheres and carry out the second ultraviolet light curing (wavelength 365 nm, intensity 15 mW / cm 2 ) to form a hydrogel layer. Among them, the concentration of the suspension containing polyethylene glycol diacrylate microspheres is 12 wt%.

[0151] Example 4

[0152] The difference between this example and Example 1 is that no boron nitride film is set, that is, the deposition of the boron nitride film is not carried out in step (1).

[0153] The remaining preparation methods and parameters are the same as those in Example 1.

[0154] Example 5

[0155] The difference between this example and Example 1 is that the thickness of the boron nitride film is 5 μm.

[0156] The remaining preparation methods and parameters are the same as those in Example 1.

[0157] Example 6

[0158] The difference between this example and Example 1 is that the density of the vertical carbon nanotube array is 1×10 9 roots / cm 2 .

[0159] The remaining preparation methods and parameters are the same as those in Example 1.

[0160] Example 7

[0161] The difference between this example and Example 1 is that the density of the vertical carbon nanotube array is 1×10 12 roots / cm 2 .

[0162] The remaining preparation methods and parameters are the same as those in Example 1.

[0163] Example 8

[0164] The difference between this example and Example 1 is that in step (3), the MATLAB-generated Hilbert curve 5th-order space-filling algorithm is not used for fractal geometric electrode arrangement.

[0165] The remaining preparation methods and parameters are the same as those in Example 1.

[0166] Example 9

[0167] The difference between this example and Example 1 is that the average particle size of the polyethylene glycol diacrylate microspheres is 0.5 μm.

[0168] The remaining preparation methods and parameters are the same as those in Example 1.

[0169] Example 10

[0170] The difference between this example and Example 1 is that the average particle size of the polyethylene glycol diacrylate microspheres is 3.5 μm.

[0171] The remaining preparation methods and parameters are the same as those in Example 1.

[0172] Example 11

[0173] The difference between this example and Example 1 is that in step (1), oxygen plasma treatment is not performed.

[0174] The remaining preparation methods and parameters are the same as those in Example 1.

[0175] Example 12

[0176] The difference between this example and Example 1 is that in step (3), instead of using a nanoimprinting machine to transfer the flexible electrode array obtained in step (2), a combination of traditional photolithography technology and screen printing technology is adopted.

[0177] The remaining preparation methods and parameters are the same as those in Example 1.

[0178] Example 13

[0179] The difference between this example and Example 1 is that in step (4), the spraying of the prepolymer solution is not carried out.

[0180] The remaining preparation methods and parameters are the same as those in Example 1.

[0181] Comparative Example 1

[0182] The difference between this comparative example and Example 1 is that silver nanowires are not provided, that is, the immersion of the silver nanowire ethanol dispersion liquid is not carried out in step (2).

[0183] The remaining preparation methods and parameters are the same as those in Example 1.

[0184] Comparative Example 2

[0185] The difference between this comparative example and Example 1 is that a single-layer graphene layer is not provided, that is, the growth of the single-layer graphene layer is not carried out in step (2).

[0186] The remaining preparation methods and parameters are the same as those in Example 1.

[0187] Analysis:

[0188] In summary, through multi-faceted collaborative design, the high-density EEG electrode array provided by the present invention not only solves the problems of insufficient spatial resolution and poor wearing comfort of traditional EEG devices while maintaining low interface impedance and high signal fidelity, but also improves the electrode density and the quality of the collected high-density EEG signals, which provides a hardware basis for the analysis of neural activities and has subversive potential in the field of high-performance brain-computer interfaces.

[0189] It can be seen from the comparison between Example 1 and Examples 4-5 that if the boron nitride film is not provided, the dielectric loss of the polymer film is too large, which will have an adverse impact on aspects such as signal quality, energy consumption, device stability, and biocompatibility; if the thickness of the boron nitride film is too thick, it will affect signal transmission and reduce the electrode sensitivity.

[0190] As can be seen from the comparison between Example 1 and Examples 6-7, if the density of the vertical carbon nanotube array is too small, the quality of the electrode signal will decline and the electrode performance will be unstable; if the density of the vertical carbon nanotube array is too large, additional noise and interference signals may be generated, reducing the signal quality and also affecting biocompatibility.

[0191] As can be seen from the comparison between Example 1 and Example 8, if the 5th-order space-filling algorithm of the Hilbert curve is not generated using MATLAB for fractal geometric electrode arrangement, the signal will be greatly interfered and the service life of the electrode will decline.

[0192] As can be seen from the comparison between Example 1 and Example 11, if the oxygen plasma treatment is not carried out in step (1), the long-term electrical stability of the electrode under dynamic deformation is poor.

[0193] As can be seen from the comparison between Example 1 and Example 12, compared with the combination of traditional lithography technology and screen printing technology, the nanoimprinting machine realizes sub-micron pattern transfer through single-time imprinting with a high-precision template. While maintaining the yield, it improves the processing efficiency and does not require polluting steps such as photoresist development, with the advantages of high resolution, high yield and green manufacturing.

[0194] As can be seen from the comparison between Example 1 and Comparative Example 1, if the silver nanowires are not provided, the conductivity of the electrode is poor and it is not conducive to forming a continuous conductive path.

[0195] As can be seen from the comparison between Example 1 and Comparative Example 2, if the single-layer graphene layer is not provided, the conductivity of the electrode is poor and the interfacial stability is also poor.

[0196] It should be noted that the present invention uses the above-mentioned examples to illustrate the process method of the present invention, but the present invention is not limited to the above process steps, that is, it does not mean that the present invention must rely on the above process steps to be implemented. Those skilled in the art should understand that any improvement of the present invention, the equivalent replacement of the raw materials selected by the present invention, the addition of auxiliary components, the selection of specific methods, etc. all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A high-density EEG electrode array, characterized in that: The high-density EEG electrode array comprises: Dielectric flexible substrate; A flexible electrode array, wherein the flexible electrode array is distributed on one side surface of the dielectric substrate layer, and the flexible electrode array includes a stacked vertical carbon nanotube array and a carbon layer in a direction away from the dielectric substrate layer, and metal nanowires are distributed in the array unit gaps of the vertical carbon nanotube array; A hydrogel layer is located on the outer surface of the flexible electrode array.

2. The high-density EEG electrode array according to claim 1, characterized in that: The dielectric flexible substrate includes a polymer film and an inorganic film stacked in a direction close to the flexible electrode array; Preferably, the material of the polymer film includes any one of polydimethylsiloxane, polyimide, polystyrene or polyethylene terephthalate, or a combination of at least two thereof; Preferably, the material of the inorganic film includes any one of boron nitride, aluminum oxide or silicon carbide, or a combination of at least two thereof; Preferably, the inorganic film has a thickness of 1-3 μm.

3. The high-density EEG electrode array according to claim 1 or 2, characterized in that: The density of the vertical carbon nanotube array is 5×10 9 -5×10 11 Root / cm 2 ; Preferably, the height of the vertical carbon nanotube array is 4-8 μm; Preferably, the carbon layer comprises a graphene layer; Preferably, the thickness of the carbon layer is 0.3-1.2 nm; Preferably, the material of the metal nanowires includes any one of silver, copper or platinum, or a combination of at least two of them.

4. The high-density EEG electrode array according to any one of claims 1 to 3, characterized in that: The hydrogel layer is a self-adhesive hydrogel layer; Preferably, the hydrogel layer contains polyethylene glycol diacrylate microspheres; Preferably, the average particle size of the polyethylene glycol diacrylate microspheres is 1-3 μm; Preferably, the distribution density of the polyethylene glycol diacrylate microspheres is 1×10 4 -1×10 5 Pieces / cm 2 ; Preferably, the hydrogel layer is a bionic gecko foot structure; Preferably, the peel strength of the self-adhesive hydrogel layer is 0.5-1.2 N / cm 2 .

5. The high-density EEG electrode array according to any one of claims 1 to 4, characterized in that: The electrode distribution density of the high-density EEG electrode array is ≥ 20 electrodes / cm 2 ; Preferably, in the EEG electrode array, the spacing between electrodes is ≤2.5 mm.

6. A method for preparing a high-density EEG electrode array as claimed in any one of claims 1 to 5, characterized in that: The preparation method comprises the following steps: (a) preparing a dielectric flexible substrate; A carbon layer and a vertical carbon nanotube array are sequentially prepared on a metal foil, and then metal nanowires are deposited in the array unit gaps of the vertical carbon nanotube array to obtain an electrode array to be transferred; (b) transferring the electrode array to be transferred onto one side surface of the dielectric flexible substrate, and then curing the substrate so that the vertical carbon nanotube array contacts the dielectric flexible substrate, and then removing the metal foil to expose the carbon layer; (c) coating a hydrogel precursor solution on the outer surface of the carbon layer and curing the solution to form a hydrogel layer.

7. The method for preparing a high-density EEG electrode array according to claim 6, characterized in that: The method for preparing the dielectric flexible substrate in step (a) comprises: A polymer film and an inorganic film are sequentially prepared on a hard substrate; Preferably, before preparing the inorganic film on the polymer film, the surface of the polymer film is first subjected to plasma treatment; Preferably, the method for preparing the inorganic film comprises chemical vapor deposition; Preferably, the chemical vapor deposition method includes the following parameters: The reactant gas includes a boron source and a nitrogen source at a flow ratio of 1:(2-6), the growth temperature is 350-450°C, the growth time is 1-3h, and the growth pressure is 2-8Pa; Preferably, the method for preparing the carbon layer in step (a) comprises chemical vapor deposition; Preferably, the method for preparing the vertical carbon nanotube array in step (a) comprises the following steps: A metal catalyst layer is first prepared on the carbon layer, and then a vertical carbon nanotube array is grown; Preferably, the thickness of the metal catalyst layer is 3-8 nm; Preferably, the growth method of the vertical carbon nanotube array comprises a chemical vapor deposition method, wherein the reactant gas comprises a gaseous carbon source and hydrogen at a flow ratio of 1:(8-12); Preferably, the method for depositing the metal nanowires in step (a) comprises: The semi-finished product after preparing the vertical carbon nanotube array in step (a) is immersed in a metal nanowire dispersion liquid for electrophoretic deposition and then annealed.

8. The method for preparing a high-density EEG electrode array according to claim 6 or 7, characterized in that: Before transferring the electrode array to be transferred in step (b), a fractal geometric electrode arrangement is performed using a Hilbert curve 5th order space filling algorithm; Preferably, the transfer method in step (b) comprises nanoimprint lithography.

9. The method for preparing a high-density EEG electrode array according to any one of claims 6 to 8, characterized in that: The preparation method comprises the following steps: (1) mixing a polymer prepolymer and a curing agent in a mass ratio of (8-12):1, coating the mixture on a silicon wafer surface, and curing the mixture at 60-100° C. for 1-3 h to form a polymer film; The polymer film is subjected to oxygen plasma treatment, and then a boron nitride film is deposited on the surface of the polymer film by chemical vapor deposition to obtain a dielectric flexible substrate; the chemical vapor deposition method includes the following parameters: The reactant gas includes a boron source and a nitrogen source at a flow ratio of 1:(2-6), the growth temperature is 350-450°C, the growth time is 1-3h, and the growth pressure is 2-8Pa; (2) preparing a carbon layer on a metal foil, then depositing a metal catalyst layer with a thickness of 3-8 nm, then growing a vertical carbon nanotube array with a height of 4-8 μm on the metal catalyst layer by chemical vapor deposition, and finally immersing the obtained semi-finished product in a metal nanowire dispersion with a concentration of 0.4-0.8 wt%, applying an electric field of 10-20 V / cm for 30-50 min of electrophoretic deposition to fill the array units of the vertical carbon nanotube array with metal nanowires, and annealing at 180-220° C. for 1-3 h after the deposition; in the chemical vapor deposition method, the reactant gas includes a gaseous carbon source and hydrogen with a flow ratio of 1:(8-12), and the deposition temperature is 600-700° C.; (3) using a Hilbert curve 5th order space filling algorithm to perform fractal geometric electrode arrangement, then spin coating photoresist on the surface of the boron nitride film of the dielectric flexible substrate, and using a nanoimprinter to transfer the flexible electrode array obtained in step (2) at a pressure of 0.4-0.8 MPa, and then curing it so that the vertical carbon nanotube array contacts the dielectric flexible substrate, then using laser selective sintering of metal nanowires, and using an acid etching method to remove the metal foil to expose the carbon layer; (4) preparing a prepolymer solution, wherein the prepolymer solution comprises acrylamide, sodium alginate and a solvent; The prepolymer solution is coated on the surface of the carbon layer in step (3) and subjected to a first curing, and then coated with a suspension of polyethylene glycol diacrylate microspheres and subjected to a second curing to form a hydrogel layer; wherein the concentration of the suspension containing polyethylene glycol diacrylate microspheres is 8-12 wt %.

10. An application of the high-density EEG electrode array according to any one of claims 1 to 5, characterized in that: The high-density EEG electrode array is applied in the field of brain-computer interface.

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