WO2023065496A1

WO2023065496A1 - Ultra-narrow, high-density flexible electrode having multiple independent channels, preparation method therefor, and use thereof

Info

Publication number: WO2023065496A1
Application number: PCT/CN2021/137595
Authority: WO
Inventors: 刘志远; 李光林; 孙静; 杨焕; 王琳
Original assignee: 中国科学院深圳先进技术研究院
Priority date: 2021-10-18
Filing date: 2021-12-13
Publication date: 2023-04-27
Also published as: CN114098746A

Abstract

An ultra-narrow, high-density flexible electrode having multiple independent channels, a preparation method therefor, and a use thereof, belonging to the technical field of sensors. The method comprises: (1) spin coating a sacrificial layer on a silicon wafer, and drying to form a film; (2) spin coating an elastomer solution and drying same; (3) after pasting a mask on a flexible substrate, sputtering or evaporating a metal conductive film, and obtaining a flexible electrode provided with conductive channels; (4) covering the metal film at both ends of the electrode, evenly spin coating an uncovered area with a diluted solution of the elastomer solution, drying, or drying the diluted solution to form a film and then sticking the film on the surface of the electrode; (5) cutting the electrode, releasing the electrode from the silicon wafer, cutting off the excess substrate at one end for detection, and obtaining an ultra-narrow, high-density flexible electrode having multiple independent channels. The prepared flexible electrode has good conductivity and high repeatability and has a large number of channels. The detection ends of the channels of the electrode are independent from one another, thus physiological electrical signals at different sites can be detected at the same time, and said ends can be attached to the body without relative slippage.

Description

A flexible electrode with ultra-narrow, high-density and multiple relatively independent channels, its preparation method and application

technical field

The invention belongs to the technical field of sensors, and in particular relates to an ultra-narrow, high-density flexible electrode with multiple relatively independent channels, a preparation method and application thereof.

Background technique

In recent years, electronic materials have become more and more diversified, and the types of electronic devices are more abundant. Various electronic detection or functional devices used in the human body have also become research hotspots, including the detection of specific neuron signals in the human body. The nervous system is the dominant system that regulates the physiological activities of the body. From the perspective of the cell scale, the action potential generated by a single neuron is the basic signal of neural activity; from the perspective of the organization, the sum of the action potentials of a large number of adjacent neurons is the local field potential. Nervous tissue is soft, compliant and undergoes constant microscopic and macroscopic movements, such as the spinal cord and many peripheral nerves, are subject to up to 20% tension during everyday activities.

Although traditional hard implanted electrodes have good chemical inertia and electrical conductivity, they have poor followability, do not fit well with the human body, and cannot move synchronously with the nervous system. Long-term use may easily cause risks such as tissue inflammation or even necrosis. Based on this The heartbeat is corrupted or even unobtainable. When these electrodes are used, they are often unable to detect physiological electrical signals in a large range due to the small number of channels or the mutual binding between channels, and the measured signal data has certain contingencies. This mechanical mismatch of hard sensors is inevitable and often causes tissue damage and neuroinflammation when implanted into the body. Soft electronic devices used as implantable electrodes can significantly improve the mechanical fit of neural interfaces. Although the existing soft electrodes can detect physiological electrical signals under the premise of conforming to the soft characteristics of the body, the larger soft electrodes can only detect the local potential of nerve tissue, and it is difficult to further detect the action potential of a single neuron. In addition, neither the limited number of electrodes nor the mutual binding between electrode channels can realize the detection of physiological electrical signals in multiple regions at the same time. In the closest prior art, the invention patent with the application number 201810209677.4 discloses a flexible and stretchable multi-channel convex surface muscle electrode, which is mainly composed of array-distributed measuring electrodes, cylindrical spacers, mesh Substrate, interconnect wires and packaging layers. The electrode is designed with a raised structure. During the test, the sensing electrode is more likely to be in close contact with the human skin, and can measure EMG signals comfortably and non-invasively for a long time. However, the number of electrode channels is still limited, and there are few detection sites, making it difficult to collect physiological electrical signals in a large area. In addition, the size of a single detection electrode is relatively large, which cannot accurately measure physiological electrical signals in a designated small area. The invention patent with application number 201910418554.6 discloses a method for preparing flexible array microelectrodes. The method uses a soft photolithography coating process to combine a flexible substrate with a high-conductivity material to prepare a flexible electrode with a size below the submillimeter. However, it is easy to change the properties of the flexible mold by using an ion bonding machine, which increases the uncertainty of the electrode performance, and cannot guarantee the close fit between the conductive material and the flexible mold. The invention is an ultra-narrow, high-density, multi-channel flexible electrode with relatively independent channels. On the one hand, it can realize the simultaneous acquisition of electrical signals of nerve tissue at multiple points, and on the other hand, it can realize the detection of specific neuron action potential and the electrical Stimulation can realize the collection of fixed-point physiological electrical signals in small areas of the human body or apply electrical stimulation to assist clinical treatment.

Femtosecond laser cutting technology has gradually matured and is now used in the medical field, such as eye vision correction. The femtosecond cutting technology is introduced into the preparation of flexible electrodes. On the one hand, the femtosecond laser cutting speed is femtosecond level, which can realize the rapid cutting of flexible materials; on the other hand, the laser beam can be adjusted to cut specific Shaped electrodes to achieve electrode patterning. In addition, laser cutting has high precision, and the width of the cut can be as low as 10 microns, so electrodes with a width of tens of microns can be precisely cut with high repeatability. The invention introduces the femtosecond cutting technology into the flexible electrode processing, and can quickly prepare ultra-narrow, high-density flexible electrodes with multiple relative independent channels by changing the preset power and cutting trajectory.

technical problem

In view of the problems existing in the above-mentioned prior art, the object of the present invention is to design and provide an ultra-narrow, high-density flexible electrode with multiple relatively independent channels and its preparation method and application. The ultra-narrow and high-density flexible electrode with multiple relatively independent channels prepared by this patent has the characteristics of simple experimental process, low cost and convenient large-scale production.

technical solution

In order to achieve the above object, the present invention adopts the following technical solutions:

A method for preparing a flexible electrode with ultra-narrow and high-density multiple relatively independent channels, characterized in that it comprises the following steps:

(1) Spin-coat a sacrificial layer on the surface of the silicon wafer, and dry it to form a film;

(2) Spin coat a layer of elastomer solution and dry to obtain a flexible substrate;

(3) After attaching a mask on the flexible substrate obtained in step (2), place it in a magnetron sputtering or evaporation equipment to sputter or evaporate a metal conductive film to obtain a flexible electrode with a conductive path; the flexible electrode realizes electrical conductivity Patterning, using a mask to achieve local deposition of metal, to obtain electrodes of a specific shape. Wherein, the two ends of the non-spin-coated elastomer solution are respectively used as the signal detection end and the electrical signal transmission end;

(4) Cover the metal film at both ends of the flexible electrode obtained in step (3), spin-coat the elastomer solution dilution evenly on the uncovered area except the above-mentioned covering, remove the covering layer, and dry to obtain a flexible electrode with an insulating layer ;

Alternatively, take a silicon wafer and spin-coat a sacrificial layer, then spin-coat a layer of elastomer solution dilution, dry and release to obtain a thin film, and attach it to the substrate of a flexible electrode with a conductive path by self-adhesive to obtain a flexible electrode with an insulating layer ;

(5) Cut the flexible electrode obtained in step (4) with a femtosecond laser cutting machine, release it from the silicon wafer, cut off the excess substrate at one end used for detection, and prepare an ultra-narrow, high-density, multi-relatively independent channel A flexible electrode, the detection end of which is relatively independent.

The method for preparing a flexible electrode with ultra-narrow and high-density multiple relatively independent channels is characterized in that the sacrificial layer in the step (1) is easily soluble in water, and the sacrificial layer includes poly(4-styrenesulfonate Sodium acid) aqueous solution.

The method for preparing a flexible electrode with ultra-narrow and high-density multiple relatively independent channels is characterized in that the elastomer solution in the step (2) includes PDMS or SEBS-toluene solution, and the concentration of the SEBS-toluene solution is 15-30 wt%.

The method for preparing an ultra-narrow and high-density flexible electrode with multiple relatively independent channels is characterized in that in the step (3), the edge is covered by the mask plate, and the middle rectangular area is exposed.

The method for preparing a flexible electrode with ultra-narrow, high-density and multiple relatively independent channels is characterized in that the elastomer solution diluent in step (4) includes PDMS diluent or SEBS diluent, and the elastomer solution dilutes The dilution ratio of the liquid is 10-30:1 between the diluent of the elastomer solution and the solvent.

The method for preparing a flexible electrode with ultra-narrow, high-density and multiple relatively independent channels is characterized in that the direction of cutting in the step (5) is perpendicular to the direction of the exposed metal film at both ends of the flexible electrode, and the cutting position is Cut directly from the outside of the exposed gold film at one end to the outside of the other exposed gold film, and cut the entire metal film and the flexible substrate under the metal film.

The method for preparing an ultra-narrow and high-density flexible electrode with multiple relatively independent channels is characterized in that the specific steps of releasing the cut electrode from the silicon wafer in the step (5) are as follows: the cut electrode The electrodes are placed in a glass container filled with deionized water, and left to stand until the sacrificial layer is completely dissolved, that is, the electrodes are separated from the silicon wafer.

An ultra-narrow, high-density flexible electrode with multiple relatively independent channels prepared by any one of the preparation methods.

A battery comprising the flexible electrode with ultra-narrow and high-density multiple relatively independent channels.

An application of the flexible electrode with ultra-narrow, high-density and multiple relatively independent channels in the simultaneous collection of electrical signals of nerve tissue at multiple points.

The method of using femtosecond laser cutting technology to prepare ultra-narrow and high-density flexible electrodes with multiple relatively independent channels has the characteristics of simple preparation steps, less time-consuming, low cost, environment-friendly and high repeatability. The specific performance is as follows: (1) PSS (poly(4-styrene sodium sulfonate) aqueous solution) has good hydrophilicity, and it can be used as a hydrophilic sacrificial layer to complete the ultra-narrow and high-density flexible electrode with multiple independent channels. (2) The size of a single electrode channel is small, which can realize the electrophysiological signal detection and selective electrical stimulation of a single neuron; (3) The femtosecond laser cutting technology can cut out in a short time Thousands of channel electrodes, independent of each other, can detect physiological electrical signals at different sites in a large area at the same time; (4) The electrodes are small in size, soft and stretchable, simple in structure, and good in followability, which can reduce the risk of implantation side effects on the organization.

Beneficial effect

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

1. The present invention applies femtosecond laser cutting technology to the preparation of ultra-narrow and high-density flexible electrodes with multiple relatively independent channels. The prepared flexible electrodes have good conductivity and high repeatability, and the number of channels can reach thousands, and the electrodes Each channel is relatively independent. In theory, it can detect physiological electrical signals at different points in a large area at the same time. The size of a single channel of a flexible electrode is small and can reach the micron level. In theory, it can detect the action potential of some single neurons. The electrode is small in size, soft and stretchable, simple in structure, and flexible. In theory, it can fit the tissue well without relative slippage, and can reduce the side effects on the tissue caused by implantation.

2. The preparation scheme of the ultra-narrow and high-density flexible electrode with multiple relatively independent channels of the present invention has the characteristics of less time-consuming, high electrode precision, controllable and adjustable engineering parameters, simple experimental process, low cost and convenient for large-scale mass production.

Description of drawings

Figure 1 is a schematic diagram of the front view and cross-section of the ultra-narrow, high-density, multi-relatively independent channel flexible electrode structure;

Figure 2 is the SEM image of the ultra-narrow and high-density flexible electrode with multiple relatively independent channels.

Embodiments of the present invention

Example 1:

The specific experimental plan is as follows:

(1) Prepare a specific concentration of SEBS-toluene solution for later use. The concentration of commonly used SEBS-toluene solution is 15% (wt%) to 30% (wt%).

(2) Poly(4-styrene sodium sulfonate) (PSS)-water solution was uniformly coated on a commercial silicon wafer and dried, and the silicon wafer was processed into a hydrophilic material.

(3) Spin-coat the SEBS-toluene solution evenly on the silicon wafer treated in step (2), and let stand until the toluene is completely volatilized.

(4) Cover the mask plate on the flexible substrate prepared in (3) (cover the edge and expose the rectangular area in the middle), and place it in a magnetron sputtering device to sputter a metal film to obtain a stable conduction flexible electrode.

(5) The two ends of the rectangular gold film part of the flexible electrode in (4) (a group of opposite sides of the rectangular area) are covered with a mask, and the PDMS dilution is evenly spin-coated on the unmasked area, and the mask is dried after drying. Take it off to complete the packaging of the flexible electrode.

(6) Use femtosecond laser cutting technology to cut the packaged flexible electrode prepared in (5) into ultra-narrow and high-density flexible electrodes with multiple relatively independent channels. The cutting direction is perpendicular to the exposed two sections of gold film, and the cutting position is Cut directly from the outside of the exposed gold film at one end to the outside of the other exposed gold film, that is, to ensure that the gold film and the flexible substrate under the gold film are completely cut into strips, as shown in Figures 1 and 2.

(7) The electrode prepared in (6) was placed in a glass container filled with deionized water, and stood for 1 h until the PSS was completely dissolved to realize the separation of the flexible electrode and the silicon wafer. This process is only for the hydrophilic dissolution of PSS and does not destroy the integrity of the electrode.

The flexible electrode obtained in (7) was taken out of the deionized water and then cut along the cutting frame shown by the dotted line in Figure 1, that is, the excess flexible substrate outside the dotted line was cut off to prepare an ultra-narrow electrode with independent signal channels (including the detection end). High-density flexible electrodes with multiple relatively independent channels, the redundant flexible substrate is retained at the signal transmission port without being completely spread out, thus ensuring the spatial distance of the multi-channel electrodes (the entire electrode is like a tassel).

Claims

A method for preparing a flexible electrode with ultra-narrow and high-density multiple relatively independent channels, characterized in that it comprises the following steps:

(1) Spin-coat a sacrificial layer on the surface of the silicon wafer, and dry it to form a film;

(2) Spin coat a layer of elastomer solution and dry to obtain a flexible substrate;

(3) After pasting a mask on the flexible substrate obtained in step (2), place it in a magnetron sputtering or evaporation equipment to sputter or evaporate a metal conductive film to obtain a flexible electrode with a conductive path;

(4) Cover the metal film at both ends of the flexible electrode obtained in step (3), spin-coat the elastomer solution dilution evenly on the uncovered area except the above-mentioned covering, remove the covering layer, and dry to obtain a flexible electrode with an insulating layer ;

Alternatively, take a silicon wafer and spin-coat a sacrificial layer, then spin-coat a layer of elastomer solution dilution, dry and release to obtain a thin film, and attach it to the substrate of a flexible electrode with a conductive path by self-adhesive to obtain a flexible electrode with an insulating layer ;

Cut the flexible electrode obtained in step (4) with a femtosecond laser cutting machine, release it from the silicon wafer, cut off the excess substrate at one end for detection, and prepare an ultra-narrow, high-density flexible electrode with multiple relatively independent channels.
A method for preparing a flexible electrode with ultra-narrow, high-density and multiple relatively independent channels according to claim 1, characterized in that the sacrificial layer in the step (1) is easily soluble in water, and the sacrificial layer comprises poly(4 - sodium styrene sulfonate) aqueous solution.
The preparation method of a flexible electrode with ultra-narrow and high-density multi-relative independent channels according to claim 1, wherein the elastomer solution in the step (2) includes PDMS or SEBS-toluene solution, and the SEBS-toluene The concentration of the solution is 15-30 wt%.
The method for manufacturing a flexible electrode with ultra-narrow and high-density multi-relatively independent channels according to claim 1, characterized in that in the step (3), the mask plate covers the edges and exposes the middle rectangular area.
The preparation method of a flexible electrode with ultra-narrow, high-density and multi-relatively independent channels according to claim 1, characterized in that the elastomer solution diluent in the step (4) includes PDMS diluent or SEBS diluent, said The dilution ratio of the elastomer solution diluent is 10-30:1 between the elastomer solution diluent and the solvent.
A method for preparing an ultra-narrow, high-density, multi-relatively independent channel flexible electrode according to claim 1, characterized in that the direction of cutting in the step (5) is perpendicular to the direction of the exposed metal film at both ends of the flexible electrode , the cutting position is to cut directly from the outside of the exposed gold film at one end to the outside of the other exposed gold film, and cut the entire metal film and the flexible substrate under the metal film.
A method for preparing a flexible electrode with ultra-narrow, high-density and multiple relatively independent channels as claimed in claim 1, wherein the specific steps of releasing the cut electrode from the silicon wafer in the step (5) are as follows: Place the cut electrode in a glass container filled with deionized water, and let it stand until the sacrificial layer is completely dissolved, that is, the electrode is separated from the silicon wafer.
A flexible electrode with ultra-narrow, high-density and multiple relatively independent channels prepared by the preparation method according to any one of claims 1-7.
A battery comprising flexible electrodes with ultra-narrow, high-density and multiple relatively independent channels as claimed in claim 8.
An application of the flexible electrode with ultra-narrow, high-density and multiple relatively independent channels as claimed in claim 8 in the simultaneous acquisition of electrical signals of nerve tissue at multiple points.