CN112450938A

CN112450938A - Hydrogel electrode for long-term electroencephalogram acquisition and preparation method thereof

Info

Publication number: CN112450938A
Application number: CN202011337718.1A
Authority: CN
Inventors: 刘景全; 申跟财
Original assignee: Shanghai Jiaotong University
Current assignee: Shanghai Jiaotong University
Priority date: 2020-11-25
Filing date: 2020-11-25
Publication date: 2021-03-09
Anticipated expiration: 2040-11-25
Also published as: CN112450938B

Abstract

The invention provides a hydrogel electrode for long-term electroencephalogram acquisition and a preparation method thereof, wherein the preparation method comprises the following steps: a support frame for supporting the entire electrode; the conductive hydrogel structure is used for contacting with the skin to obtain a bioelectricity signal and is arranged on the bottom surface of the supporting frame; a conductive member for converting a bioelectric signal into an electronic current, one end of the conductive member penetrating into the inside of the support frame and having its end exposed to the upper surface of the support frame, the other end of the conductive member extending into the conductive hydrogel structure; and the metal snap fastener is used for connecting the conductive part with an external lead, is arranged on the supporting frame, is positioned above the conductive part and is in contact with the conductive part. The invention does not need to use conductive paste, has convenient installation, strong moisturizing performance, repeated use, low skin-electrode contact impedance and high signal acquisition quality, and is suitable for acquiring bioelectricity signals for a long time; the hair-free and soft pillow can be used in a hair area and a hair-free area of the head of a human body, and is high in flexibility and comfort.

Description

Hydrogel electrode for long-term electroencephalogram acquisition and preparation method thereof

Technical Field

The invention relates to the technical field of electroencephalogram interfaces, in particular to a hydrogel electrode for long-term electroencephalogram acquisition and a preparation method thereof.

Background

Electroencephalograms (EEG) can be used to diagnose brain related diseases, as well as sleep problems and psychological disorders. At present, a silver/silver chloride electrode is generally used in cooperation with conductive paste for testing electroencephalogram signals, and the contact impedance of the skin electrode measured by the wet electrode and the quality of the electroencephalogram signals are ideal. However, the installation of wet electrodes is very inconvenient, and the residual conductive paste needs to be removed by washing the electrode contact portion after each use, which makes the test cumbersome. In addition, the use of conductive pastes may cause skin irritation in a subject.

A search of the existing literature shows that Haoqiang Huanga et al, in micromechines (2019)10, write "Flexible Multi-Layer Semi-Dry Electrode for Scale EEG Measurements at Hairy Sites" ("Flexible Multi-Layer Semi-Dry Electrode for Scalp Hair zone electroencephalogram measurement" ("micromachine"). The research prepares a semi-dry electrode, and the electrode does not need to use conductive paste and is convenient to mount. The electrolyte can flow out of the electrodes to the skin, thereby lowering the impedance of the stratum corneum, the outermost layer of the skin. However, the electrolyte in the electrode gradually dries in the using process, and the electrolyte needs to be added again to be used continuously. Guangli Li et al, journal of neuro-engineering (2020)17, drafted "firmware engineering EEG applications," a novel printable flexible Ag/AgCl dry electrode array for robust recording of EEG signals at forehead sites "(" journal of neuro-engineering "). The research prepares a printable flexible Ag/AgCl dry electrode array for recording forehead electroencephalogram signals, the electrode has a sweat absorption function, artifact signals caused by sweating are reduced, and the electrode is convenient to use. However, the electrode is not suitable for acquiring brain electricity in a hairy area. The ideal brain electrode should have the characteristics of low contact impedance, high signal acquisition quality, capability of acquiring in a haired area, high comfort level and the like. Moreover, the electrode should be convenient to use and reusable.

Through search and discovery, Chinese patent with application number CN201710591655.4 discloses a stretchable high-density electromyographic signal electrode slice based on hydrogel, which relates to the field of biological electromyography, and comprises: the polypropylene polymer is used as a base layer and a sealing layer material, the hydrogel is used as a conductive electrode and a lead, and the conductive electrode has the full-transparent physical characteristic. The hydrogel material has conductivity and can be used for manufacturing electrodes and leads. The hydrogel electrodes were an 8x8 array, a fully transparent gel-like material. The hydrogel electrode is fixed on the basal layer on one side and is not encapsulated on the other side for contacting with the skin. The hydrogel lead and the electrode are made of the same material, one end of the hydrogel lead is connected with the hydrogel electrode, and the other end of the hydrogel lead is connected with an external electronic component. The hydrogel leads are sealed by the base layer and the sealing layer to prevent contact with the skin during use. However, when the electrode is used in a hair area of the head, the hair blocks the electrode from directly contacting the scalp, so that the electrode cannot be applied to the hair area.

Disclosure of Invention

Aiming at the defects in the prior art, the invention aims to provide a hydrogel electrode for long-term electroencephalogram acquisition and a preparation method thereof.

The invention provides a hydrogel electrode for long-term electroencephalogram acquisition, which comprises:

a support frame for supporting the entire electrode;

the conductive hydrogel structure is used for contacting with the skin to acquire a bioelectrical signal and is arranged on the bottom surface of the support frame;

a conductive member for converting a bioelectrical signal into an electronic current, one end of the conductive member penetrating into the inside of the support frame and having an end portion thereof exposed to an upper surface of the support frame, the other end of the conductive member protruding into the conductive hydrogel structure;

and the metal snap fastener is used for connecting the conductive part with an external lead, is arranged on the supporting frame, is positioned above the conductive part and is in contact with the conductive part.

Preferably, the bottom of the supporting frame is provided with a claw-shaped component, and the claw-shaped component extends into the conductive hydrogel structure and is used for fixing the conductive hydrogel structure.

Preferably, the electrically conductive hydrogel structure is in the shape of a flat disc.

Preferably, the base of the flat disc is provided with a downwardly extending cylindrical member to facilitate passage of the electrically conductive hydrogel structure through the hair into contact with the skin.

Preferably, the material of the conductive hydrogel structure is an electronic hydrogel containing carbon nanotubes or silver wire material, or an ionic hydrogel containing potassium chloride or sodium chloride ionic electrolyte.

Preferably, the ratio of electrolyte to water in the ionic hydrogel is 1:10 to 1: 1000.

Preferably, the material of the conductive hydrogel structure contains a moisture retention material.

Preferably, the ratio of water to the moisturizing material in the material of the conductive hydrogel structure is 1:10-10: 1.

Preferably, the conductive member is made of any one of silver chloride, gold, silver, and platinum.

The second aspect of the invention provides a preparation method of a hydrogel electrode for long-term electroencephalogram acquisition, which comprises the following steps:

preparing a support frame;

preparing a mould required for preparing a reverse mould of the conductive hydrogel structure;

mounting a conductive member and a metal snap on the support frame;

placing a support frame with an installed conductive component and metal snap fasteners in the mold;

and pouring the hydrogel precursor solution into the mold, and taking out the hydrogel precursor solution from the mold after the hydrogel precursor solution is solidified and molded to obtain the hydrogel electrode for long-term electroencephalogram acquisition.

Compared with the prior art, the invention has at least one of the following beneficial effects:

according to the electrode, the electrode structure is improved, the conductive hydrogel structure is arranged, the electrode has good moisture retention performance and can be suitable for collecting electroencephalogram for a long time, compared with the traditional wet electrode structure, the improved electrode structure does not need to use conductive paste when electroencephalogram is collected, and an experiencer does not need to wash hair after use; the hydrogel is reusable, and the low resistance of the hydrogel is utilized, so that the skin-electrode contact resistance of the electrode is far lower than that of a dry electrode, and the quality of the acquired signal is high.

The electrode has higher flexibility, and the conductive hydrogel structure is further set into two electrode structures, namely a flat disc-shaped electrode structure and a columnar component structure, so that the electrode is suitable for collecting electroencephalograms in a forehead hairless area and can also be suitable for collecting electroencephalograms in a hairless area; can be used in the hair area and the non-hair area of the head of a person, and has high comfort level.

According to the electrode, the claw-shaped component is further arranged on the supporting frame, so that the conductive hydrogel structure and the supporting frame can be tightly connected.

Drawings

Other features, objects and advantages of the invention will become more apparent upon reading of the detailed description of non-limiting embodiments with reference to the following drawings:

FIG. 1 is a schematic structural diagram of a hydrogel electrode for long-term brain electrical acquisition according to a preferred embodiment of the present invention;

FIG. 2 is a schematic structural diagram of a hydrogel electrode for long-term brain electrical acquisition having a conductive hydrogel structure with columnar members according to a preferred embodiment of the present invention;

FIG. 3 is a flow chart of a method for preparing a hydrogel electrode for long-term electroencephalogram acquisition according to a preferred embodiment of the present invention, at step S1;

FIG. 4 is a flow chart of a method for preparing a hydrogel electrode for long-term electroencephalogram acquisition according to a preferred embodiment of the present invention, step S3;

FIG. 5 is a flow chart of a method for preparing a hydrogel electrode for long-term electroencephalogram acquisition according to a preferred embodiment of the present invention at step S5;

the scores in the figure are indicated as: 1 is a metal snap fastener, 2 is a conductive component, 3 is a supporting frame, 4 is a conductive hydrogel structure, 31 is a claw-shaped component, and 41 is a columnar component.

Detailed Description

The present invention will be described in detail with reference to specific examples. The following examples will assist those skilled in the art in further understanding the invention, but are not intended to limit the invention in any way. It should be noted that variations and modifications can be made by persons skilled in the art without departing from the spirit of the invention. All falling within the scope of the present invention.

Referring to fig. 1, a schematic structural diagram of a hydrogel electrode for long-term electroencephalogram acquisition according to a preferred embodiment of the present invention includes: a supporting frame 3, a conductive hydrogel structure, a conductive part 2 and a metal snap fastener 1, wherein,

the support frame 3 serves to support the entire electrode and to secure the electrically conductive hydrogel structure 4 to the electrically conductive member 2.

The conductive hydrogel structure 4 is arranged on the bottom surface of the support frame 3 and is used for contacting with the skin to acquire bioelectric signals.

One end of the conductive member 2 penetrates into the support frame 3 and has its end exposed to the upper surface of the support frame 3, and the other end of the conductive member 2 protrudes into the conductive hydrogel structure 4; the conductive member 2 serves to convert the bioelectrical signal into an electronic current. Preferably, the conductive member 2 is a member having an inverted T-shaped cross section; the vertical sides of the inverted T-shaped member are inserted into the support frame 3 and the horizontal sides are inserted into the conductive hydrogel structure 4. The conductive component 2 is made of silver chloride; in other embodiments, conductive materials such as gold, silver, or platinum may be substituted.

The metal snap fastener 1 is used for connecting the conductive component 2 with an external lead, and the metal snap fastener 1 is arranged on the supporting frame 3, is positioned above the conductive component 2 and is in contact with the conductive component 2. The metal snap fastener 1 is connected with a lead, so that the electrode is convenient to disassemble, and can be directly pulled out after the electrode is damaged and then replaced by a new electrode.

In other preferred embodiments, referring to fig. 1, the bottom of the supporting frame 3 is provided with a claw 31, and the claw 31 extends into the conductive hydrogel structure 4 to fix the conductive hydrogel structure 4, so that the conductive hydrogel structure 4 can be in close contact with the supporting frame 3. Preferably, the number of the claw members 31 is at least two or more.

In other partially preferred embodiments, the conductive hydrogel structure 4 is in the shape of a flat disk.

In other preferred embodiments, in order to make the hydrogel electrode easier to pass through hair and thus better contact with the skin, referring to fig. 2, a downwardly extending pillar-like member 41 is provided at the bottom of the flat disc-like conductive hydrogel structure 4. The number of the columnar members 41 is two or more. Preferably, the bottom of the claw member 31 extends to the inside of the columnar member 41; most preferably, extending the bottom of the claw members 31 to the bottom of the columnar members 41 reinforces the integrity of the columnar members 41 with the superstructure.

In some other preferred embodiments, the conductive hydrogel structure 4 is an electronic hydrogel containing carbon nanotubes or silver wires, or an ionic hydrogel containing potassium chloride or sodium chloride ionic electrolyte.

In some other preferred embodiments, the ionic hydrogel has a ratio of electrolyte to water of from 1:10 to 1: 1000. As a preferable mode, the electrolyte added into the ionic hydrogel is potassium chloride, and the ratio of the potassium chloride to the water is 1: 15.

In some other preferred embodiments, the material of the conductive hydrogel structure 4 contains a moisture-retaining material. The moisturizing material can be glycerol. As a preferable mode, the moisturizing material added to the hydrogel precursor of the conductive hydrogel structure 4 is glycerin, and the ratio of water to glycerin in the hydrogel precursor is 3: 4. The components of the hydrogel precursor are known components and can be prepared by adopting an existing experimental method.

In other preferred embodiments, the ratio of water to moisturizing material in the material of the conductive hydrogel structure 4 is 1:10 to 10: 1.

The hydrogel electrode for long-term electroencephalogram acquisition can be prepared by the following method, and as shown in fig. 3, 4 and 5, the hydrogel electrode comprises the following steps:

s1: preparing a support frame; the support frame as shown in fig. 3 may be prepared by 3D printing technology;

s2: preparing a mould required for preparing a reverse mould of the conductive hydrogel structure; the mold required for the back mold can be printed out by 3D printing technology.

S3: mounting the conductive member and the metal snap fastener on the support frame prepared at S1, as shown in fig. 3, inserting one end of the conductive member into the inside of the support frame and exposing the end thereof to form a contact surface with the upper surface of the support frame; and mounting the metal snap fastener on the upper surface of the support frame, and covering the metal snap fastener on the end surface of the conductive component to enable the metal snap fastener to be in contact with the conductive component.

S4: the support frame, with the conductive member and the metal snap-fastener installed, was placed in a mold at S3, and then the hydrogel precursor solution containing glycerin was poured into the mold.

S5: and after the hydrogel is solidified and formed, taking out the hydrogel from the mold to obtain the hydrogel electrode for long-term electroencephalogram acquisition as shown in figure 5.

The foregoing description of specific embodiments of the present invention has been presented. It is to be understood that the present invention is not limited to the specific embodiments described above, and that various changes or modifications may be made by one skilled in the art within the scope of the appended claims without departing from the spirit of the invention.

Claims

1. A hydrogel electrode for long-term electroencephalogram acquisition, comprising:

a support frame for supporting the entire electrode;

2. The hydrogel electrode for long-term electroencephalogram acquisition as recited in claim 1, wherein a claw-like member is provided at the bottom of the support frame, the claw-like member extending into the conductive hydrogel structure for fixing the conductive hydrogel structure.

3. The hydrogel electrode for long-term electroencephalogram acquisition of claim 1, wherein the conductive hydrogel structure is in the shape of a flat disc.

4. The hydrogel electrode for long-term brain electrical acquisition of claim 3, wherein the bottom of the flat disk shape is provided with a downwardly extending cylindrical member to facilitate the conductive hydrogel structure to pass through hair to contact the skin.

5. The hydrogel electrode for long-term electroencephalogram acquisition according to claim 1, wherein the material of the conductive hydrogel structure is an electronic hydrogel containing carbon nanotubes or silver wire material, or an ionic hydrogel containing potassium chloride or sodium chloride ionic electrolyte.

6. The hydrogel electrode for long-term electroencephalogram acquisition of claim 5, wherein the ratio of electrolyte to water in the ionic hydrogel is 1:10-1: 1000.

7. The hydrogel electrode for long-term electroencephalogram acquisition according to claim 1, wherein the material of the conductive hydrogel structure contains a moisturizing material.

8. The hydrogel electrode for long-term electroencephalogram acquisition according to claim 7, wherein the ratio of water to the moisturizing material in the material of the conductive hydrogel structure is 1:10-10: 1.

9. The hydrogel electrode for long-term electroencephalogram acquisition according to any one of claims 1 to 8, wherein the conductive component is made of any one of silver chloride, gold, silver or platinum.

10. A method of making a hydrogel electrode for long-term electrical brain acquisition as claimed in any one of claims 1 to 9, comprising:

preparing a support frame;

mounting a conductive member and a metal snap on the support frame;