CN112886304B

CN112886304B - Flexible non-embedded semi-dry electrode for brain-computer interface, preparation method thereof and brain-computer interface module

Info

Publication number: CN112886304B
Application number: CN202110021895.7A
Authority: CN
Inventors: 伍晖; 刘峻琛; 洪波; 李文正; 林森; 雷鸣
Original assignee: Tsinghua University
Current assignee: Tsinghua University
Priority date: 2021-01-08
Filing date: 2021-01-08
Publication date: 2022-03-15
Anticipated expiration: 2041-01-08
Also published as: CN112886304A

Abstract

The invention discloses a flexible non-embedded semi-dry electrode for a brain-computer interface, a preparation method of the flexible non-embedded semi-dry electrode and a brain-computer interface module. The flexible non-embedded semi-dry electrode for the brain-computer interface comprises: the flexible substrate consists of metalized hydrogel and metalized sponge, and the metalized hydrogel is sleeved on the metalized sponge; the metalized hydrogel comprises a hydrogel matrix and an electrode material loaded on the hydrogel matrix, and the metalized sponge comprises a sponge matrix, and the electrode material and a structural reinforcing material loaded on the sponge matrix. The flexible non-embedded semi-dry electrode for the brain-computer interface has excellent water storage performance and conductivity, good mechanical and chemical stability, no conductive gel material and skin friendliness.

Description

Flexible non-embedded semi-dry electrode for brain-computer interface, preparation method thereof and brain-computer interface module

Technical Field

The invention relates to the field of material science, in particular to a flexible non-embedded semi-dry electrode for a brain-computer interface, a preparation method of the flexible non-embedded semi-dry electrode and a brain-computer interface module.

Background

Since the 80's of the 20 th century, brain-computer interface (BCI) technology was developed that could take human electroencephalography (EEG), analyze it, and convert it into instructions to specific devices to perform the required operations. By collecting and analyzing EEG, BCI can provide rich real-time brain information, including a person's mental state, etc. Human beings can communicate or operate with various devices without requiring muscle movement by means of the command mapping of the BCI.

Effective BCI requires low impedance between the human skin and the electrodes. The brain-computer interface can be divided into a wet electrode, a dry electrode and a semi-dry electrode according to the amount of electrolyte in the system. The wet electrode is a conductive gel assisted Ag/AgCl electrode, which is currently the most popular commercial BCI electrode due to the stable electrode potential. However, the use of Ag/AgCl electrodes involves two time consuming and uncomfortable processes, a skin preparation process and a conductive gel preparation process, wherein the conductive gel may also have negative effects on the skin, such as allergy. Another key problem with Ag/AgCl electrodes is the inability to bypass the hair and make good contact with the scalp. The thick hair can be seen as an insulating layer, limiting sufficient contact between the rigid electrode and the scalp. The potential harm of the conductive gel to the hair and scalp and the subsequent cumbersome process of having to go through shampooing determine that it is not suitable for long-hair subjects. Therefore, some researchers have started the study of dry and semi-dry electrodes. The dry electrode has no electrolyte, so that the problem of conductive gel can be well overcome, but because the impedance of the human stratum corneum is very high, the impedance of the stratum corneum cannot be reduced to an acceptable range in many fields without introducing the electrolyte. The semi-dry electrode is usually introduced with electrolyte such as partial sodium chloride solution, and fluid electrolyte is used to reduce the impedance of the stratum corneum without introducing conductive gel, but the difficulty in engineering is higher due to the control of the slow release process of the electrolyte solution, the semi-dry electrode is used as a promising brain-computer interface electrode, the large-scale application of the semi-dry electrode does not appear, and the existing brain-computer interface semi-dry electrode still needs to be improved.

Disclosure of Invention

The present invention is directed to solving, at least to some extent, one of the technical problems in the related art. Therefore, the invention aims to provide a flexible non-embedded semi-dry electrode for a brain-computer interface, a preparation method thereof and a brain-computer interface module. The flexible non-embedded semi-dry electrode for the brain-computer interface has excellent water storage performance and conductivity, good mechanical and chemical stability, no conductive gel material and skin friendliness.

In one aspect of the invention, the invention provides a flexible non-embedded semi-dry electrode for a brain-computer interface. According to the embodiment of the invention, the flexible non-embedded semi-dry electrode of the brain-computer interface comprises: the flexible substrate consists of metalized hydrogel and metalized sponge, and the metalized hydrogel is sleeved on the metalized sponge; the metalized hydrogel comprises a hydrogel matrix and an electrode material loaded on the hydrogel matrix, and the metalized sponge comprises a sponge matrix, and the electrode material and a structural reinforcing material loaded on the sponge matrix.

According to the flexible non-embedded semi-dry electrode for the brain-computer interface, the flexible matrix is composed of the metalized hydrogel and the metalized sponge. The hydrogel matrix has excellent flexibility, water storage and water slow release performances, and the sponge matrix has excellent flexibility, water storage and water release performances at one time. The hydrogel matrix and the sponge matrix are compounded to be used as the flexible matrix of the brain-computer interface semi-dry electrode after loading electrode materials, and the electrode can be in full contact with the skin in a flexible non-embedded mode without the aid of conductive gel, so that the electrode is more friendly to the skin compared with the traditional Ag/AgCl rigid electrode adopting the conductive gel. Meanwhile, the sponge matrix has strong water storage and one-time moisture release capacities, can release a large amount of electrolyte when being used for the first time, moistens the cuticle of the scalp, establishes an ion channel between the scalp and an electrode and conducts signals; the hydrogel matrix has strong water storage and moisture slow release capacity, can continuously and slowly release electrolyte into the moistened scalp stratum corneum and the established ion channel in the using process, and the slow release speed is not too fast to short circuit adjacent electrode sites. In addition, because the electrode is flexible, the electrode can bypass the tested hair in the using process, the length of an ion path is shortened, an electronic path with lower impedance is responsible for conducting signals, and the impedance of the whole acquisition circuit is reduced.

In addition, the flexible non-embedded semi-dry brain-computer interface electrode according to the above embodiment of the present invention may further have the following additional technical features:

in some embodiments of the invention, the hydrogel matrix is selected from at least one of a polyvinyl alcohol hydrogel, a sodium alginate hydrogel.

In some embodiments of the invention, the sponge matrix is formed from at least one selected from the group consisting of melamine, polyurethane, and polyvinyl alcohol.

In some embodiments of the invention, the electrode material is a metal nanowire.

In some embodiments of the present invention, the metal nanowire is selected from at least one of a gold nanowire and a silver nanowire.

In some embodiments of the present invention, the metal nanowires have a diameter of 50 to 100nm and a length of 50 to 200 μm.

In some embodiments of the present invention, the content of the electrode material in the flexible matrix is 1 to 2 wt%.

In some embodiments of the present invention, the structural reinforcement material is selected from at least one of polyvinyl butyral, polyvinyl pyrrolidone.

In some embodiments of the present invention, the flexible non-embedded semi-dry brain-computer interface electrode further comprises: a reservoir in which the flexible substrate is placed.

In some embodiments of the invention, the storage liquid is an aqueous solution of sodium chloride and glycerol.

In some embodiments of the present invention, in the storage liquid, the concentration of sodium chloride is 0.9 to 20 wt% with respect to water, and the concentration of glycerol is 1 to 30 wt% with respect to water.

In another aspect of the invention, the invention provides a method for preparing the flexible non-embedded semi-dry brain-computer interface electrode of the embodiment. According to an embodiment of the invention, the method comprises: (1) mixing a hydrogel raw material with water, and adding an aqueous solution of sodium chloride and glycerol into the obtained mixed solution to obtain a hydrogel precursor solution; (2) dispersing an electrode material in a dispersing agent to obtain a first electrode material dispersion liquid; adding the first electrode dispersion liquid into an electrode mould, and volatilizing the dispersing agent to obtain the electrode mould with the surface deposited with an electrode material; (3) adding the hydrogel precursor solution into the electrode mould with the electrode material deposited on the surface, and carrying out hydrogel crosslinking treatment to load the electrode material on a hydrogel matrix to obtain a metalized hydrogel; (4) mixing the structural reinforcing material with a dispersing agent, and dispersing the electrode material in the obtained mixed solution to obtain a second electrode material dispersion solution; soaking a sponge matrix by using the second electrode material dispersion liquid so as to load the structural reinforcing material and the electrode material on the sponge matrix, and drying to obtain a metalized sponge; (5) and assembling the metalized hydrogel and the metalized sponge to obtain the flexible non-embedded semi-dry brain-computer interface electrode. Therefore, the method can easily realize the quick and mass preparation of the flexible non-embedded brain-computer interface semi-dry electrode of the embodiment.

In addition, the method for preparing the flexible non-embedded semi-dry brain-computer interface electrode according to the above embodiment of the invention may further have the following additional technical features:

in some embodiments of the invention, the mass ratio of the hydrogel raw material to the water is (0.5-2): 7.

In some embodiments of the invention, the dispersant is selected from at least one of water, ethanol, ethylene glycol.

In some embodiments of the present invention, the content of the electrode material in the first electrode material dispersion is 20 to 50 wt%.

In some embodiments of the invention, the hydrogel crosslinking treatment is chemical crosslinking or cyclic freeze-thaw crosslinking.

In some embodiments of the present invention, in the second electrode material dispersion, the content of the electrode material is 1 to 30 wt%, and the content of the structural reinforcing material is 0.1 to 1mg/100 mL.

In some embodiments of the invention, the structural reinforcement material is mixed with the dispersant at 40-80 ℃.

In some embodiments of the invention, the soaking is performed at a pressure of 1000 to 3000 Pa.

In some embodiments of the invention, the method further comprises: and placing the flexible non-embedded semi-dry electrode of the brain-computer interface into a storage liquid for later use, wherein the storage liquid is an aqueous solution of sodium chloride and glycerol.

In yet another aspect of the invention, a brain-computer interface module is provided. According to an embodiment of the invention, the brain-computer interface module comprises: the flexible non-embedded semi-dry electrode for the brain-computer interface in the embodiment or the flexible non-embedded semi-dry electrode for the brain-computer interface prepared by the method in the embodiment is arranged on the shell; the top and the bottom of the shell are provided with openings, and an accommodating space is formed inside the shell; the flexible non-embedded semi-dry electrode of the brain-computer interface is arranged in the accommodating space and extends out of the shell from an opening at the bottom of the shell; the connecting piece is arranged at the opening at the top of the shell. In the working process of the brain-computer interface module, electrolyte is adsorbed in the flexible non-embedded brain-computer interface semi-dry electrode, and the part of the flexible non-embedded brain-computer interface semi-dry electrode, which extends out of the shell, is in contact with the scalp to be tested to obtain signals. The shell can effectively prevent electrolyte in the electrode from volatilizing or releasing moisture to the direction other than the contact surface of the electrode and the scalp, and the service life of the electrode is prolonged.

In addition, the brain-computer interface module according to the above embodiment of the present invention may further have the following additional technical features:

in some embodiments of the invention, the connectors include an electrode-rear connector provided at an opening at the top of the housing and a housing-electrode cap connector provided at the side of the housing.

Additional aspects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.

Drawings

The above and/or additional aspects and advantages of the present invention will become apparent and readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:

fig. 1 is a schematic structural diagram of a flexible non-embedded brain-computer interface semi-dry electrode according to an embodiment of the invention;

fig. 2 is a schematic structural diagram of a flexible non-embedded semi-dry electrode of a brain-computer interface according to an embodiment of the invention;

fig. 3 is a photograph of a flexible non-embedded semi-dry brain-computer interface electrode in a storage solution according to an embodiment of the present invention;

fig. 4 is a schematic flow chart of a method for preparing a flexible non-embedded semi-dry brain-computer interface electrode according to an embodiment of the invention;

fig. 5 is a schematic structural diagram of a brain-computer interface module according to an embodiment of the present invention.

Detailed Description

Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The examples, where specific techniques or conditions are not indicated, are to be construed according to the techniques or conditions described in the literature in the art or according to the product specifications. The reagents or instruments used are not indicated by the manufacturer, and are all conventional products commercially available.

In the description of the present invention, it is to be understood that the terms "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate orientations or positional relationships based on those shown in the drawings, and are only for convenience of description and simplicity of description, but do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, are not to be construed as limiting the present invention.

Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the present invention, "a plurality" means at least two, e.g., two, three, etc., unless specifically limited otherwise.

In the present invention, unless otherwise expressly stated or limited, the first feature "on" or "under" the second feature may be directly contacting the first and second features or indirectly contacting the first and second features through an intermediate. Also, a first feature "on," "over," and "above" a second feature may be directly or diagonally above the second feature, or may simply indicate that the first feature is at a higher level than the second feature. A first feature being "under," "below," and "beneath" a second feature may be directly under or obliquely under the first feature, or may simply mean that the first feature is at a lesser elevation than the second feature.

In one aspect of the invention, the invention provides a flexible non-embedded semi-dry electrode for a brain-computer interface. According to the embodiment of the invention, the flexible non-embedded semi-dry electrode of the brain-computer interface comprises: the flexible substrate is composed of metalized hydrogel and metalized sponge, and the metalized hydrogel is sleeved on the metalized sponge. The metalized hydrogel comprises a hydrogel matrix and an electrode material loaded on the hydrogel matrix, and the metalized sponge comprises a sponge matrix, and the electrode material and a structural reinforcing material loaded on the sponge matrix.

The flexible non-embedded semi-dry brain-computer interface electrode according to the embodiment of the invention is further described in detail below.

The specific shape of the flexible substrate is not particularly limited, and the flexible substrate can be processed into any specification according to actual needs. According to some embodiments of the invention, the flexible substrate may be a segmented cylinder, as shown in FIGS. 1-3. Specifically, 1 is a metalized hydrogel, and 2 is a metalized sponge. The metalized hydrogel 1 is a segmented cylinder, the interior of the segmented cylinder is hollow, and the metalized sponge 2 is arranged in the metalized hydrogel 1. One skilled in the art can load at least part of the hydrogel matrix with a metal material according to actual needs, for example, as shown in fig. 1, the metalized hydrogel 1 includes a hydrogel matrix 1a and a metal material 1b, and the metal material 1b is loaded on the lower cylinder of the hydrogel matrix 1 a.

The specific kinds of hydrogel matrix and sponge matrix used as the above-mentioned flexible matrix are not particularly limited and can be selected by those skilled in the art according to actual needs. According to some embodiments of the invention, the hydrogel matrix may be selected from at least one of a polyvinyl alcohol hydrogel, a sodium alginate hydrogel. The sponge base may be formed of at least one selected from the group consisting of melamine, polyurethane, and polyvinyl alcohol. The material has good flexibility and strong water storage performance, and can not cause adverse effect on skin.

According to some embodiments of the invention, the electrode material is a metal nanowire. The metal nanowires are easily loaded on the hydrogel matrix and the sponge matrix, the loading position is easy to control, and the metal nanowires can be uniformly loaded on a target area of the matrix. According to some embodiments of the invention, the metal nanowire is selected from at least one of a gold nanowire and a silver nanowire. The metal nanowires have sensitive signal response and are skin-friendly.

According to some embodiments of the present invention, the metal nanowire may have a diameter of 50 to 100nm (e.g., 50nm, 60nm, 70nm, 80nm, 90nm, 100nm, etc.) and a length of 50 to 200 μm (e.g., 50 μm, 60 μm, 80 μm, 100 μm, 120 μm, 140 μm, 160 μm, 180 μm, 200 μm, etc.). The inventors found that if the diameter of the metal nanowire is too large, the flexibility thereof is reduced, affecting the mechanical strength and stability of the electrode; if the length is too small, the conductivity is reduced, which affects the transmission of electrical signals.

According to some embodiments of the invention, the electrode material is present in the flexible matrix in an amount of 1 to 2 wt%, such as 1 wt%, 1.1 wt%, 1.2 wt%, 1.3 wt%, 1.4 wt%, 1.5 wt%, 1.6 wt%, 1.7 wt%, 1.8 wt%, 1.9 wt%, 2 wt%, and the like. Aiming at the structural characteristics of the flexible non-embedded semi-dry electrode of the computer-computer interface, the content of the electrode material in the flexible substrate is controlled to be in the range, so that the electrode can be ensured to have sufficient conductivity.

The structure reinforcing material can improve the strength of the flexible substrate on the premise of keeping the flexibility of the substrate, thereby improving the durability of the electrode and not causing excessive adverse effects on the conductivity of the electrode. According to some embodiments of the present invention, the structural reinforcing material may be at least one selected from the group consisting of polyvinyl butyral and polyvinyl pyrrolidone. Therefore, the electrode has good flexibility and better strength and conductivity.

According to some embodiments of the invention, the flexible non-embedded brain-computer interface semi-dry electrode of the invention further comprises: and storing the liquid, and placing the flexible substrate in the storing liquid. By placing the flexible substrate in the reservoir for use, the flexible substrate can be caused to adsorb the reservoir to facilitate the establishment of an ionically conductive pathway during use.

According to some embodiments of the invention, the storage liquid is an aqueous solution of sodium chloride and glycerol. The inventor finds that the sodium chloride can provide an ion conduction channel for the electrode, the glycerol can infiltrate the stratum corneum, and meanwhile, the combination of the sodium chloride and the glycerol can play a role in regulating the mechanical properties of the hydrogel. Therefore, by adopting the aqueous solution of sodium chloride and glycerol as the storage solution, the conductivity, mechanical property and other aspects of the flexible non-embedded semi-dry brain-computer interface electrode can be further improved.

According to some embodiments of the invention, in the storage liquid, the concentration of sodium chloride relative to water may be 0.9 to 20 wt% (e.g., 0.9 wt%, 2 wt%, 5 wt%, 10 wt%, 12 wt%, 15 wt%, 20 wt%, etc.), and the concentration of glycerol relative to water may be 1 to 30 wt% (e.g., 1 wt%, 2 wt%, 5 wt%, 10 wt%, 12 wt%, 15 wt%, 20 wt%, 25 wt%, 30 wt%, etc.). By controlling the concentration of sodium chloride and glycerol in the storage liquid within the range, the compatibility of the rest skin can be further improved, the impedance of the skin is reduced, and the electrode is ensured to efficiently and sensitively acquire an electric signal under the condition of non-embedded contact with the skin. If the concentration of solute is too low, the solution is not favorable for forming an ion conduction channel and reducing the impedance of the stratum corneum; if the concentration of the solute is too high, the difference between the concentration of the solute and the electrolyte environment of a human body is too large, and adverse reactions can occur.

In summary, the flexible non-embedded semi-dry electrode for a brain-computer interface of the present invention has at least one of the following advantages: excellent water storage performance, water slow release performance, high conductivity, good flexibility, high mechanical and chemical stability, hair bypassing capability and no need of conductive gel assistance.

In another aspect of the invention, the invention provides a method for preparing the flexible non-embedded semi-dry brain-computer interface electrode of the embodiment. The method of the flexible non-embedded brain-computer interface semi-dry electrode is described in detail with reference to fig. 4. According to an embodiment of the invention, the method comprises:

s100: preparation of hydrogel precursor solution

In the step, a hydrogel raw material is mixed with water, and an aqueous solution of sodium chloride and glycerol is added to the obtained mixed solution to obtain a hydrogel precursor solution. Specifically, the hydrogel raw material may be at least one of polyvinyl alcohol and sodium alginate.

According to some embodiments of the present invention, the mass ratio of hydrogel raw material to water may be (0.5-2: 7), such as 0.5:7, 0.75:7, 1:7, 1.25:7, 1.5:7, 1.75:7, 2:7, etc. By controlling the mass ratio of the hydrogel raw material to water in the step within the range, the hydrogel has higher mechanical strength and water storage capacity on the premise of ensuring good hydrogel forming. If the consumption of the hydrogel raw material is too much, the solution stability is not facilitated, the hydrogel forming is influenced, the water content of the hydrogel is reduced, and the electrode is influenced in the subsequent steps; if the amount of the hydrogel raw material is too small, the hydrogel is not easily formed, and the mechanical strength of the hydrogel is lowered.

According to some embodiments of the present invention, in the above aqueous solution of sodium chloride and glycerol, the concentration of sodium chloride with respect to water may be 0.9 to 20 wt% (e.g., 0.9 wt%, 2 wt%, 5 wt%, 10 wt%, 12 wt%, 15 wt%, 20 wt%, etc.), and the concentration of glycerol with respect to water may be 1 to 30 wt% (e.g., 1 wt%, 2 wt%, 5 wt%, 10 wt%, 12 wt%, 15 wt%, 20 wt%, 25 wt%, 30 wt%, etc.). By controlling the concentration of sodium chloride and glycerol in the storage liquid within the range, the compatibility of the rest skin can be further improved, the impedance of the skin is reduced, and the electrode is ensured to efficiently and sensitively acquire an electric signal under the condition of non-embedded contact with the skin. If the solute concentration is too low, the reduction is not beneficial to the solution to form an ion conduction channel and reduce the impedance of the stratum corneum; if the concentration of the solute is too high, the concentration difference with the electrolyte environment of a human body is too large, adverse reactions can occur, and the stability of the hydrogel precursor solution can be influenced.

S200: obtaining an electrode mold with electrode material deposited on the surface

In the step, dispersing an electrode material in a dispersing agent to obtain a first electrode material dispersion liquid; and adding the first electrode dispersion liquid into an electrode mould, and volatilizing the dispersing agent to obtain the electrode mould with the electrode material deposited on the surface.

According to some embodiments of the present invention, the dispersant may be at least one selected from water, ethanol, and ethylene glycol, and preferably ethanol. Such solvents have a low boiling point and are easily removed in subsequent processing without affecting the electrodes.

According to some embodiments of the present invention, the content of the electrode material in the first electrode material dispersion may be 20 to 50 wt%, for example, 20 wt%, 25 wt%, 30 wt%, 35 wt%, 40 wt%, 45 wt%, 50 wt%, etc. Therefore, the metalized hydrogel prepared subsequently has proper conductivity and can meet the requirement of being used as a brain-computer interface.

S300: obtaining a metallized hydrogel

In the step, hydrogel precursor solution is added into an electrode mould with electrode material deposited on the surface, and hydrogel crosslinking treatment is carried out, so that the electrode material is loaded on a hydrogel matrix, and the metalized hydrogel is obtained.

According to some embodiments of the invention, the hydrogel crosslinking treatment is chemical crosslinking or cyclic freeze-thaw crosslinking. Specifically, the crosslinking mode can be selected according to the type of the hydrogel raw material, for example, the polyvinyl alcohol hydrogel precursor can be physically crosslinked in a cyclic freezing-thawing mode for 2-5 times, the more the number of cycles is, the higher the mechanical strength of the hydrogel is, but the lower the water release capacity is. The sodium alginate hydrogel can be chemically crosslinked by using a 1-3 wt% calcium chloride aqueous solution, wherein the higher the concentration of the calcium chloride aqueous solution is, the higher the mechanical strength of the hydrogel is, but the lower the water slow-release capacity is.

S400: obtaining a metallized sponge

In the step, a structural reinforcing material is mixed with a dispersing agent, and an electrode material is dispersed in the obtained mixed solution to obtain a second electrode material dispersion solution; and soaking the sponge matrix by using the second electrode material dispersion liquid so as to load the structural reinforcing material and the electrode material on the sponge matrix, and drying to obtain the metalized sponge.

According to some embodiments of the present invention, the dispersant may be at least one selected from water, ethanol, and ethylene glycol, and preferably ethanol. Ethanol can provide good solubility for the structural reinforcement material and disperse the electrode material well. In addition, the boiling point of the solvent is low, so that the solvent can be easily removed in subsequent treatment and cannot influence the electrode.

According to some embodiments of the invention, the structural reinforcement material is mixed with the dispersant at 40-80 ℃ (e.g., 40 ℃, 50 ℃, 60 ℃, 70 ℃, 80 ℃, etc.). By mixing the structural reinforcing material with the dispersant at the above temperature, the dispersing effect of the structural reinforcing material in the resulting mixed liquid can be further improved, and if the temperature is too high, the structural reinforcing material may be deteriorated. In addition, magnetic stirring can be assisted in the mixing process to further improve the dispersion effect.

According to some embodiments of the present invention, in the second electrode material dispersion, the content of the electrode material may be 1 to 30 wt% (e.g., 1 wt%, 2 wt%, 5 wt%, 10 wt%, 15 wt%, 20 wt%, 25 wt%, 30 wt%, etc.), and the content of the structural reinforcing material may be 0.1 to 1mg/100mL (e.g., 0.1mg/100mL, 0.2mg/100mL, 0.5mg/100mL, 0.8mg/100mL, 1mg/100mL, etc.). The inventor finds that if the amount of the electrode material is too small, the contact impedance of the prepared electrode is larger than 10k omega, and the prepared electrode cannot meet the requirement of being used as a brain-computer interface. If the concentration of the structural reinforcing material is too high, the subsequent mixing of the electrode material and the mixed solution is not facilitated, the overall conductivity of the electrode is adversely affected, and the conductivity of the electrode is reduced. By controlling the concentration of the structural reinforcing material in the mixed solution in the step to be 0.1-1 mg/100mL, the strength of the flexible substrate can be effectively improved on the premise of ensuring the flexibility of the substrate and the overall conductivity of the electrode.

According to some embodiments of the invention, the soaking is performed at a pressure of 1000 to 3000Pa, such as 1000Pa, 1200Pa, 1500Pa, 1800Pa, 2000Pa, 2500Pa, 3000Pa, etc. The inventor finds that the infiltration of the precursor solution to the flexible substrate and the locking of the electrode material on the flexible substrate skeleton can be further facilitated by utilizing vacuum treatment to assist the loading of the active component.

S500: assembling flexible non-embedded semi-dry electrode for brain-computer interface

In the step, the metalized hydrogel and the metalized sponge are assembled to obtain the flexible non-embedded semi-dry brain-computer interface electrode.

According to some embodiments of the invention, the method for preparing the flexible non-embedded brain-computer interface semi-dry electrode further comprises: and placing the flexible non-embedded semi-dry electrode of the brain-computer interface in storage liquid for later use. Preferably, the storage solution is an aqueous solution of sodium chloride and glycerol with the same solute concentration as in S100.

In conclusion, the method for preparing the flexible non-embedded semi-dry electrode for the brain-computer interface can simply and efficiently prepare a large amount of flexible non-embedded semi-dry electrodes for the brain-computer interface in the embodiment.

In addition, it should be noted that all the features and advantages described above for the flexible non-embedded semi-dry electrode product for a computer-to-computer interface are also applicable to the above method for preparing a flexible non-embedded semi-dry electrode for a computer-to-computer interface, and are not described in detail here.

In yet another aspect of the invention, a brain-computer interface module is provided. Referring to fig. 5, according to an embodiment of the present invention, the brain-computer interface module includes: the flexible non-embedded semi-dry brain-computer interface electrode comprises a shell 10, a connecting piece 20, and the flexible non-embedded semi-dry brain-computer interface electrode 30 of the embodiment or the flexible non-embedded semi-dry brain-computer interface electrode 30 prepared by the method of the embodiment.

In the brain-computer interface module, the top and the bottom of the housing 10 have openings, and the interior has an accommodating space; the flexible non-embedded semi-dry electrode 30 of the brain-computer interface is arranged in the accommodating space and extends out of the shell 10 from an opening at the bottom of the shell 10; the connector 20 is provided at an opening at the top of the housing 10. In the working process of the brain-computer interface module, electrolyte is adsorbed in the flexible non-embedded brain-computer interface semi-dry electrode, and the part of the flexible non-embedded brain-computer interface semi-dry electrode, which extends out of the shell, is in contact with the scalp to be tested to obtain signals. The shell can effectively prevent electrolyte in the electrode from volatilizing or releasing moisture to the direction other than the contact surface of the electrode and the scalp, and the service life of the electrode is prolonged.

According to some embodiments of the invention, the above-mentioned connections comprise an electrode-back end connection 21 and a shell-electrode cap connection 22. An electrode-rear end connector 21 is provided at an opening at the top of the case 10, and a case-electrode cap connector 22 is provided at the side of the case 10. In some embodiments, the lead may be connected with the flexible non-embedded brain-computer interface semi-dry electrode 30 inside the housing 10 through the electrode-rear end connection 21 so as to output a signal.

In addition, it should be noted that all the features and advantages described above for the flexible non-embedded semi-dry electrode for a computer-to-computer interface and the method for manufacturing the flexible non-embedded semi-dry electrode for a computer-to-computer interface are also applicable to the computer-to-computer interface module, and are not described in detail herein.

The invention will now be described with reference to specific examples, which are intended to be illustrative only and not to be limiting in any way.

Example 1

Polyvinyl alcohol (PVA) powder and ultrapure water are prepared into a solution with the mass ratio of PVA to water being 1:6, and magnetic stirring and heating at 90 ℃ are assisted in the process. After PVA was completely dissolved, an aqueous solution of sodium chloride and glycerol was added thereto. The mass ratio of sodium chloride to glycerol to water is 0.35:0.7:1, the mass ratio of water in the water solution of sodium chloride and glycerol to water in the PVA solution is 1:6, and the content of sodium chloride and the content of glycerol in the obtained system are 5 wt% and 10 wt%. An electrode mold is manufactured according to the required electrode shape, ethanol dispersion liquid of silver nanowires (50nm diameter and 200 mu m length) is dripped into the electrode mold according to the mass ratio of 1%, and after ethanol is volatilized, a layer of silver can be seen to cover the bottom surface and the side wall of the mold. Dripping the prepared hydrogel precursor into a mold, putting the mold into a refrigerator for freezing, taking the mold out of the refrigerator after the hydrogel precursor is completely frozen, unfreezing the mold in a room-temperature environment, repeating the process for three times, and after the hydrogel precursor is unfrozen for the third time, enabling the hydrogel to have the same fixed shape as the mold. The hydrogel was removed from the mold and it was seen that the silver deposited on the surface of the mold had transferred to the hydrogel surface. Polyvinyl butyral (PVB) powder and absolute ethyl alcohol are prepared into mixed liquid with the PVB concentration of 1mg/100mL, and magnetic stirring and heating at 80 ℃ are assisted in the process. Adding silver nanowires (50nm diameter and 200 μm length) into the mixed solution according to the mass ratio of 1%, and fully stirring to prepare a metallization precursor solution. Cutting the melamine sponge into a cylinder with the diameter of 3mm and the height of 3cm, soaking the cylinder into the precursor solution, and carrying out 2000Pa vacuum treatment. And (3) fully drying the sponge after the operation treatment, and plugging the sponge into a hole reserved in the hydrogel matrix to obtain the electrode with the resistance of 10k omega. Preparing a mixed aqueous solution of 5 wt% of sodium chloride and 10 wt% of glycerol as a storage solution, and putting the electrode into the storage solution for later use.

Example 2

PVA powder and ultrapure water are prepared into a solution with the mass ratio of PVA to water being 1:6, and magnetic stirring and heating at 90 ℃ are assisted in the process. After PVA was completely dissolved, an aqueous solution of sodium chloride and glycerol was added thereto. The mass ratio of sodium chloride to glycerol to water is 0.35:0.7:1, the mass ratio of water in the water solution of sodium chloride and glycerol to water in the PVA solution is 1:6, and the content of sodium chloride and the content of glycerol in the obtained system are 5 wt% and 10 wt%. An electrode mold is manufactured according to the required electrode shape, 5% of ethanol dispersion liquid of silver nanowires (50nm diameter and 200 mu m length) is dripped into the electrode mold, and after ethanol volatilizes, a layer of silver can be seen covering the bottom surface and the side wall of the mold. Dripping the prepared hydrogel precursor into a mold, putting the mold into a refrigerator for freezing, taking the mold out of the refrigerator after the hydrogel precursor is completely frozen, unfreezing the mold in a room-temperature environment, repeating the process for three times, and after the hydrogel precursor is unfrozen for the third time, enabling the hydrogel to have the same fixed shape as the mold. The hydrogel was removed from the mold and it was seen that the silver deposited on the surface of the mold had transferred to the hydrogel surface. PVB powder and absolute ethyl alcohol are prepared into mixed liquid with the PVB concentration of 1mg/100mL, and magnetic stirring and heating at 80 ℃ are assisted in the process. Adding silver nanowires (50nm diameter and 200 μm length) into the mixed solution according to the mass ratio of 5%, and fully stirring to prepare a metallization precursor solution. Cutting the melamine sponge into a cylinder with the diameter of 3mm and the height of 3cm, soaking the cylinder into the precursor solution, and carrying out 2000Pa vacuum treatment. And (3) fully drying the sponge after the operation treatment, and plugging the sponge into a hole reserved in the hydrogel matrix to obtain the electrode with the resistance of 1k omega. Preparing a mixed aqueous solution of 5 wt% of sodium chloride and 10 wt% of glycerol as a storage solution, and putting the electrode into the storage solution for later use.

Example 3

PVA powder and ultrapure water are prepared into a solution with the mass ratio of PVA to water being 1:6, and magnetic stirring and heating at 90 ℃ are assisted in the process. After PVA was completely dissolved, an aqueous solution of sodium chloride and glycerol was added thereto. The mass ratio of sodium chloride to glycerol to water is 0.35:0.7:1, the mass ratio of water in the water solution of sodium chloride and glycerol to water in the PVA solution is 1:6, and the content of sodium chloride and the content of glycerol in the obtained system are 5 wt% and 10 wt%. An electrode mold is manufactured according to the required electrode shape, ethanol dispersion liquid of silver nanowires (50nm diameter and 200 mu m length) is dripped into the electrode mold according to the mass ratio of 10%, and after ethanol is volatilized, a layer of silver can be seen to cover the bottom surface and the side wall of the mold. Dripping the prepared hydrogel precursor into a mold, putting the mold into a refrigerator for freezing, taking the mold out of the refrigerator after the hydrogel precursor is completely frozen, unfreezing the mold in a room-temperature environment, repeating the process for three times, and after the hydrogel precursor is unfrozen for the third time, enabling the hydrogel to have the same fixed shape as the mold. The hydrogel was removed from the mold and it was seen that the silver deposited on the surface of the mold had transferred to the hydrogel surface. PVB powder and absolute ethyl alcohol are prepared into mixed liquid with the PVB concentration of 1mg/100mL, and magnetic stirring and heating at 80 ℃ are assisted in the process. Adding silver nanowires (50nm diameter and 200 μm length) into the mixed solution according to the mass ratio of 10%, and fully stirring to prepare a metallization precursor solution. Cutting the melamine sponge into a cylinder with the diameter of 3mm and the height of 3cm, soaking the cylinder into the precursor solution, and carrying out 2000Pa vacuum treatment. And (3) fully drying the sponge after the operation treatment, and plugging the sponge into a hole reserved in the hydrogel matrix to obtain the electrode with the resistance of 50 omega. Preparing a mixed aqueous solution of 5 wt% of sodium chloride and 10 wt% of glycerol as a storage solution, and putting the electrode into the storage solution for later use.

Example 4

PVA powder and ultrapure water are prepared into a solution with the mass ratio of PVA to water being 1:6, and magnetic stirring and heating at 90 ℃ are assisted in the process. After PVA was completely dissolved, an aqueous solution of sodium chloride and glycerol was added thereto. The mass ratio of sodium chloride to glycerol to water is 0.35:0.7:1, the mass ratio of water in the water solution of sodium chloride and glycerol to water in the PVA solution is 1:6, and the content of sodium chloride and the content of glycerol in the obtained system are 5 wt% and 10 wt%. An electrode mold is manufactured according to the required electrode shape, ethanol dispersion liquid of silver nanowires (50nm diameter and 100 mu m length) is dripped into the electrode mold according to the mass ratio of 10%, and after ethanol is volatilized, a layer of silver can be seen to cover the bottom surface and the side wall of the mold. Dripping the prepared hydrogel precursor into a mold, putting the mold into a refrigerator for freezing, taking the mold out of the refrigerator after the hydrogel precursor is completely frozen, unfreezing the mold in a room-temperature environment, repeating the process for three times, and after the hydrogel precursor is unfrozen for the third time, enabling the hydrogel to have the same fixed shape as the mold. The hydrogel was removed from the mold and it was seen that the silver deposited on the surface of the mold had transferred to the hydrogel surface. PVB powder and absolute ethyl alcohol are prepared into mixed liquid with the PVB concentration of 1mg/100mL, and magnetic stirring and heating at 80 ℃ are assisted in the process. Adding silver nanowires (50nm diameter and 100 μm length) into the mixed solution according to the mass ratio of 10%, and fully stirring to prepare a metallization precursor solution. Cutting the melamine sponge into a cylinder with the diameter of 3mm and the height of 3cm, soaking the cylinder into the precursor solution, and carrying out 2000Pa vacuum treatment. And (3) fully drying the sponge after the operation treatment, and plugging the sponge into a hole reserved in the hydrogel matrix to obtain the electrode with the resistance of 100 omega. Preparing a mixed aqueous solution of 5 wt% of sodium chloride and 10 wt% of glycerol as a storage solution, and putting the electrode into the storage solution for later use.

In the description herein, references to the description of the term "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above are not necessarily intended to refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, various embodiments or examples and features of different embodiments or examples described in this specification can be combined and combined by one skilled in the art without contradiction.

Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention, and that variations, modifications, substitutions and alterations can be made to the above embodiments by those of ordinary skill in the art within the scope of the present invention.

Claims

1. A flexible non-embedded semi-dry electrode for a brain-computer interface is characterized by comprising:

the flexible substrate consists of metalized hydrogel and metalized sponge, and the metalized hydrogel is sleeved on the metalized sponge; the metalized hydrogel comprises a hydrogel matrix and an electrode material loaded on the hydrogel matrix, and the metalized sponge comprises a sponge matrix and the electrode material and a structural reinforcing material loaded on the sponge matrix; in the flexible substrate, the content of the electrode material is 1-2 wt%.

2. The flexible non-embedded semi-dry brain-computer interface electrode according to claim 1, wherein the hydrogel matrix is at least one selected from polyvinyl alcohol hydrogel and sodium alginate hydrogel;

optionally, the sponge matrix is formed from at least one selected from the group consisting of melamine, polyurethane, and polyvinyl alcohol.

3. The flexible non-embedded semi-dry electrode for a brain-computer interface of claim 1, wherein the electrode material is a metal nanowire;

optionally, the metal nanowires are selected from at least one of gold nanowires and silver nanowires;

optionally, the diameter of the metal nanowire is 50-100 nm, and the length of the metal nanowire is 50-200 μm.

4. The flexible non-embedded semi-dry brain-computer interface electrode according to claim 1, wherein the structural reinforcement material is at least one selected from the group consisting of polyvinyl butyral and polyvinyl pyrrolidone.

5. The flexible non-embedded brain-computer interface semi-dry electrode according to any one of claims 1 to 4, further comprising:

a storage liquid in which the flexible substrate is placed;

optionally, the storage liquid is an aqueous solution of sodium chloride and glycerol;

optionally, in the storage liquid, the concentration of sodium chloride relative to water is 0.9-20 wt%, and the concentration of glycerol relative to water is 1-30 wt%.

6. A method for preparing the flexible non-embedded semi-dry brain-computer interface electrode according to any one of claims 1 to 5, wherein the method comprises the following steps:

(1) mixing a hydrogel raw material with water, and adding an aqueous solution of sodium chloride and glycerol into the obtained mixed solution to obtain a hydrogel precursor solution;

(2) dispersing an electrode material in a dispersing agent to obtain a first electrode material dispersion liquid; adding the first electrode dispersion liquid into an electrode mould, and volatilizing the dispersing agent to obtain the electrode mould with the surface deposited with an electrode material;

(3) adding the hydrogel precursor solution into the electrode mould with the electrode material deposited on the surface, and carrying out hydrogel crosslinking treatment to load the electrode material on a hydrogel matrix to obtain a metalized hydrogel;

(4) mixing the structural reinforcing material with a dispersing agent, and dispersing the electrode material in the obtained mixed solution to obtain a second electrode material dispersion solution; soaking a sponge matrix by using the second electrode material dispersion liquid so as to load the structural reinforcing material and the electrode material on the sponge matrix, and drying to obtain a metalized sponge;

(5) and assembling the metalized hydrogel and the metalized sponge to obtain the flexible non-embedded semi-dry brain-computer interface electrode.

7. The method according to claim 6, wherein the mass ratio of the hydrogel raw material to the water is (0.5-2): 7;

optionally, the dispersant is selected from at least one of water, ethanol, ethylene glycol;

optionally, in the first electrode material dispersion liquid, the content of the electrode material is 20-50 wt%;

optionally, in the second electrode material dispersion liquid, the content of the electrode material is 1-30 wt%, and the content of the structural reinforcing material is 0.1-1 mg/100 mL;

optionally, the structural reinforcement material is mixed with the dispersant at 40-80 ℃.

8. The method according to claim 6, wherein the hydrogel crosslinking treatment is chemical crosslinking or cyclic freeze-thaw crosslinking;

optionally, the soaking is carried out under the pressure of 1000-3000 Pa.

9. The method of claim 6, further comprising:

and placing the flexible non-embedded semi-dry electrode of the brain-computer interface into a storage liquid for later use, wherein the storage liquid is an aqueous solution of sodium chloride and glycerol.

10. A brain-computer interface module, comprising: a shell, a connecting piece, the flexible non-embedded semi-dry electrode for a brain-computer interface according to any one of claims 1 to 5 or the flexible non-embedded semi-dry electrode for a brain-computer interface prepared by the method according to any one of claims 6 to 9;

the top and the bottom of the shell are provided with openings, and an accommodating space is formed inside the shell; the flexible non-embedded semi-dry electrode of the brain-computer interface is arranged in the accommodating space and extends out of the shell from an opening at the bottom of the shell;

the connecting piece is arranged at the opening at the top of the shell;

optionally, the connectors include an electrode-back connector and a shell-electrode cap connector, the electrode-back connector being disposed at an opening at the top of the shell, the shell-electrode cap connector being disposed at a side of the shell.