CN109124626B

CN109124626B - Novel passive flexible optical electrode

Info

Publication number: CN109124626B
Application number: CN201810837807.9A
Authority: CN
Inventors: 贾大功; 廖伦军; 张红霞; 刘铁根; 王睿航
Original assignee: Tianjin University
Current assignee: Tianjin University
Priority date: 2018-07-26
Filing date: 2018-07-26
Publication date: 2021-11-23
Anticipated expiration: 2038-07-26
Also published as: CN109124626A

Abstract

The invention discloses a novel passive flexible optical electrode, which is composed of five parts: an optical sensitive device (1), a flexible probe (2), a substrate (4), an electrical lead layer (5) and a transition layer (7); wherein: The flexible probe (2) is embedded in the base body (4) in an array type, the flexible probe (2) includes a free end and a bottom end, the free end is in direct contact with the living body, and the bottom end passes through the transition layer (7) to connect with the electrical leads The layer (5) is attached; the electrical conductive layer (5) is arranged on the upper surface of the transition layer (7); the electrode groove structure formed on the electrical conductive layer (5) serves as a connection with the optical sensitive device (1) Interface. The invention effectively reduces the hair interference and the contact impedance between the electrode and the scalp, and integrates with the optical sensitive device, removes the noise interference and motion artifacts caused by the wire, improves the sensitivity and compatibility of electro-optical sensing, and realizes the optical principle-based Wearable long-term stable EEG signal detection.

Description

Novel passive flexible optical electrode

Technical Field

The invention relates to the technical field of novel passive flexible optical electrodes applied to human body surface bioelectricity detection and the detection field of weak low-frequency electroencephalogram signals, in particular to a passive flexible optical electrode which is based on an electro-optical effect and can be used for electroencephalogram detection.

Background

The electroencephalogram is an external expression form of nerve cell activity in the human body, is one of the most basic physiological phenomena, and has great application value and research significance in the aspects of medical clinical diagnosis, disease prevention, brain-computer interfaces, artificial intelligence and the like. Electroencephalogram belongs to weak low-frequency signals and only has microvolt magnitude, so in order to improve detection precision, higher performance indexes need to be provided for biological detection electrodes.

The conventional biological detection electrodes comprise traditional Ag/Agcl electrodes, microneedle electrodes, flexible substrate electrodes, foam structure electrodes, textile flexible electrodes and the like. However, they still have different defects in electroencephalogram detection, such as:

1) the traditional Ag/Agcl electrode adopts metal as a main body part, so that the anti-interference capability is weak, the sensitivity is low, and due to the existence of conductive gel, the skin sensitivity is easy to cause, and the long-time electroencephalogram detection is not facilitated.

2) The micro-needle electrode penetrates through the conductive epidermis region, so that the high-impedance stratum corneum is avoided, the contact impedance is greatly reduced, and good performance is reflected on signal acquisition.

3) The flexible substrate electrode, the foam structure electrode and the textile flexible electrode have good application performance in wearing and good stability, but cannot overcome the interference problem caused by hair in electroencephalogram measurement, and influence the quality of electroencephalogram signals.

In addition, the traditional biological dry electrode is mainly applied to an electroencephalogram detection system of an electrical method, and has the problems of low signal fidelity, weak anti-electromagnetic interference capability and limited information characteristic abundance in electroencephalogram detection in a complex environment.

The electroencephalogram measurement based on the optical principle has great advantages in improving anti-interference performance and accuracy, in recent years, methods for electroencephalogram detection by using the electro-optic effect of optical crystals are available abroad, but the extraction of high-signal-to-noise ratio electroencephalogram signals is influenced by the limitation of traditional dry electrodes and the problem of low electro-optic sensing compatibility in the detection process. Therefore, it is necessary to invent a bioelectrode applied to the electroencephalogram measurement based on the optical principle to improve the compatibility and sensitivity of the electro-optical sensing.

In the prior art, patent No. CN204351823U discloses "dry electrode for bioelectricity collection". The patent states that' a flat plate type bowl cap is adopted to obtain bioelectricity on the surface of a human body, a conductive channel adopts a structure with a plurality of support legs and is input to a buffer circuit on a circuit board, and the rear end of the conductive channel is connected with the buffer circuit by a lead. The patent can effectively improve the stability and reliability of the collection of the bioelectricity. However, the high impedance problem caused by hair cannot be overcome in electroencephalogram detection, and due to the addition of the signal buffer circuit, the signal-to-noise ratio of electroencephalogram measurement in a complex environment is reduced, and the passive requirement of the front end of the acquisition system cannot be met.

Patent No. CN107411735A discloses a bioelectrical signal flexible dry electrode and a preparation method thereof. The patent describes "the electrode consists of an electrode body and an electrical connection. The electrode body is made of flexible composite materials, the three-dimensional arc-shaped curved surface is prepared to be attached to the surface of the skin, the stability and the comfort level of collected signals are improved, the electric connecting piece and the electrode body are integrally cast by adopting an integrated forming process, the contact impedance of the electric connecting piece and the electrode body is effectively reduced, and the connection of a measuring circuit is facilitated. However, due to the integral attachment, the accuracy of electroencephalogram detection is seriously influenced in a frequently-occurring area, and due to the fact that a lead is required to be externally connected with an electro-optical device in the measuring process, the compatibility of electro-optical sensing is insufficient. "

Disclosure of Invention

Aiming at the problems of low signal-to-noise ratio, and insufficient sensitivity and compatibility of electro-optic sensing in the bioelectricity acquisition process of the electrode in the prior application patent, the invention provides a novel passive flexible optical electrode which is integrally designed to ensure stable transmission of an electroencephalogram signal in the detection transmission process and enable a sandwich structure to be formed among a substrate, an electrical conductive layer and an optical sensitive device.

The invention provides a novel passive flexible optical electrode, which consists of an optical sensitive device 1, a flexible probe 2, a substrate 4, an electric conductive connection layer 5 and a transition layer 7; wherein: the flexible probes 2 are embedded into the matrix 4 in an array manner, the flexible probes 2 comprise free ends and bottom ends, the free ends are directly contacted with organisms, and the bottom ends penetrate through the transition layer 7 and are attached to the electric conduction layer 5; the electric lead layer 5 is arranged on the upper surface of the transition layer 7; an electrode groove structure formed according to the position of the array type flexible probe is arranged on the electric lead layer 5 and is used as an interface with the optical sensing device 1;

at the electric couplerA layer of flexible PI polymer is additionally arranged between the layer 5 and the substrate 4 to serve as a transition layer 7, and the polypyrrole graphene coating 3 is tightly attached to a gold film evaporated on the surface of the transition layer 7 in a disc type; coating the substrate layer with a layer of transition material, wherein the transition material is PI polymer, TiO polymer₂/TiN₂So as to ensure the preparation process and increase the adhesion between the substrate and the electric conductive layer.

And the optical sensitive device 1 is placed in the electrostatic shielding layer 6.

The flexible probe 2 is provided with a conductive channel which is composed of a polypyrrole graphene coating 3 and realizes ion and electron exchange.

The flexible probe 2 and the base body 4 are integrally formed.

Optionally, the array structure of the flexible probe 2 is arranged to be stretched at a certain angle.

Optionally, a layer of chitosan is laid on the flexible probe 2.

Optionally, a lead channel is arranged between the electrode groove structures, and the whole electrode groove structure is designed integrally.

Compared with the prior art, the wearable long-term stable electroencephalogram signal detection device effectively reduces head interference and contact impedance between the electrode and the scalp, is integrated with the optical sensitive device, removes noise interference and motion artifacts caused by wires, improves sensitivity and compatibility of electro-optical sensing, and realizes wearable long-term stable electroencephalogram signal detection based on an optical principle.

Drawings

FIG. 1 is a schematic diagram of a novel passive flexible optical electrode structure according to the present invention;

FIG. 2 is a cross-sectional view of a novel passive flexible optical electrode of the present invention;

FIG. 3 is a pictorial view of a novel passive flexible optical electrode of the present invention;

FIG. 4 is a schematic diagram of the electrical lead layer and optical sensing device structure of the present invention;

1. the device comprises an optical sensitive device, 2, a flexible probe, 3, a polypyrrole graphene coating, 4, a substrate, 5, an electric conduction layer, 6, an electrostatic shielding layer, 7, a transition layer, 11, a signal input port, 12, an optical fiber input port, 13, an optical fiber output port, 51 and an electrode groove structure.

Detailed Description

Specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings. Wherein the skilled person will understand that said parameters not being specified can be implemented with reference to the prior art.

As shown in fig. 1 and 2, a novel passive flexible optical electrode of the present invention includes a flexible probe 2 made of PDMS polymer; the back end of the flexible probe 2 takes the PDMS matrix 4 as a support position, and the flexible probes 2 are embedded into the matrix 4 in an array manner and directly contacted with the electric conductive layer 5 formed by the gold film. In order to increase the adhesion between the gold film and the substrate 4, a layer of flexible PI polymer is additionally arranged between the gold film and the substrate as a transition layer 7; meanwhile, in order to increase the contact area with the gold film and reduce the contact impedance, the polypyrrole graphene coating 3 is tightly attached to the gold film evaporated on the surface of the transition layer 7 in a disc type.

The device consists of an optical sensitive device 1, a flexible probe 2, a substrate 4, an electric conductive connection layer 5 and a transition layer 7; wherein: the flexible probes 2 are embedded into the matrix 4 in an array manner, the flexible probes 2 comprise free ends and bottom ends, the free ends are directly contacted with organisms, and the bottom ends penetrate through the transition layer 7 and are attached to the electric conduction layer 5; the electric lead layer 5 is arranged on the upper surface of the transition layer 7; and an electrode groove structure formed according to the position of the array type flexible probe is arranged on the electric lead layer 5 and is used as an interface with the optical sensing device 1.

Further, in the structure of the novel passive flexible optical electrode of the embodiment, the flexible probe is directly embedded in the substrate and is integrally formed with the substrate, so that the stability of the flexible probe is increased. The flexible probe utilizes the polypyrrole graphene coating as a conductive channel for ion and electron exchange, and greatly improves the electroencephalogram signal acquisition strength by utilizing the high conductivity and carrier mobility of the flexible probe. When the flexible probe is used, the flexible probe is preferably of an array structure and can be stretched at a certain angle, so that impedance and interference caused by dense hair areas are reduced, and the detection flexibility and comfort are improved. A layer of chitosan is optionally laid on the flexible probe to increase the hydration level with the skin and the bactericidal effect. According toIn one aspect of the invention, a flexible material is used as a substrate layer for support. Optionally, the flexible material is foam, PDMS polymer, rubber, or silicone. Preferably, the substrate layer is coated with a layer of transition material, wherein the transition material is PI polymer, TiO₂/TiN₂And the like, so as to ensure the preparation process, increase the adhesion between the substrate and the electric conductive layer and improve the signal acquisition stability. In further implementation, according to another aspect of the present invention, the electrically conductive layer may be integrally formed with a corresponding optically sensitive device by using a MEMS process, wherein the optically sensitive device specifically relates to a MEMS electro-optical device and other micro-modulation and transducer structures (optical crystal and optical waveguide structures). As an option, the electric conduction layer relates to a transparent flexible electrode plate structure prepared from a common metal film (conductive materials such as gold, silver, copper and the like), a nanowire and a conductive polymer and the like. And the electric conductive layer can be made into an electrode slot array structure corresponding to the flexible probe array structure. Lead channels can be set between the electrode grooves by referring to the optical sensing devices so as to be integrated with different optical sensing devices, and the electro-optical sensing compatibility and sensitivity are improved. In further implementation, an electrostatic protection layer is added on the outer surface of the electrode, so that electrostatic isolation and assembly use are facilitated. The electrostatic protection layer is preferably made of insulating textile cloth, insulating silica gel and rubber materials.

As shown in FIG. 4, the optical sensing device of the present invention is an M-Z model LiNbO₃Electro-optic modulators are examples: selection of x-cut y-propagating LiNbO₃The substrate and the gold film adopt an integral covering mode, two electrode groove structures 51 are formed on the gold film according to the positions of the array-type flexible probes, the integration with the corresponding signal input port 11 of the electro-optical modulator is realized, and the integrated optical fiber input 12 and the integrated optical fiber output port 13 on the two sides of the modulator are used as carrier channel ports of the modulator.

The invention solves the problems of high contact impedance between the scalp and the electrodes, poor stability, obvious motion artifact, insufficient electro-optical sensing compatibility and sensitivity in the electroencephalogram acquisition process based on the optical principle, and effectively improves the signal-to-noise ratio of the electroencephalogram acquisition.

The above embodiments are specific descriptions of the present invention. It is to be understood that the invention is not limited to the specific embodiments described above, but is not limited to the embodiments. Those skilled in the art can make various modifications without departing from the spirit and scope of the present invention.

Claims

1. A novel passive flexible optical electrode, characterized in that it is composed of five parts: an optical sensitive device (1), a flexible probe (2), a substrate (4), an electrical lead layer (5) and a transition layer (7); Wherein: the flexible probe (2) is embedded in the base body (4) in an array type, the flexible probe (2) includes a free end and a bottom end, the free end is in direct contact with the living body, and the bottom end passes through the transition layer (7) and is connected to the living body. The electrical lead layer (5) is attached; the electrical lead layer (5) is arranged on the upper surface of the transition layer (7); the electrical lead layer (5) is provided with an electrode groove formed according to the position of the array type flexible probe structure, as an interface with the optically sensitive device (1);

A layer of flexible PI polymer is added between the electrical conductor layer (5) and the base body (4) as a transition layer (7), and the polypyrrole graphene coating (3) is closely connected with the evaporation in the transition layer. The gold film on the surface of layer 7 is laminated in a disc type; a layer of transition material is used to coat the base layer, wherein the transition material involves PI polymer, TiO ₂ /TiN ₂ to ensure the preparation process and increase the base and electrical conductor layer of adhesion.

2 . The novel passive flexible optical electrode according to claim 1 , further comprising an electrostatic shielding layer ( 6 ), and the optical sensitive device ( 1 ) is placed in the electrostatic shielding layer ( 6 ). 3 .

3 . The novel passive flexible optical electrode according to claim 1 or 2 , wherein the flexible probe ( 2 ) has a conductive layer composed of a polypyrrole graphene coating ( 3 ) that realizes the exchange of ions and electrons. 4 . aisle.

4. The novel passive flexible optical electrode according to claim 1 or 2, characterized in that the flexible probe (2) is integrally formed with the base (4).

5 . The novel passive flexible optical electrode according to claim 3 , wherein a transition layer ( 7 ) is further arranged between the electrical lead layer ( 5 ) and the substrate ( 4 ); The olefin layer (3) passes through the transition layer (7) and tightly adheres to the electrical conductor layer (5).

6. The novel passive flexible optical electrode according to claim 1 or 2, characterized in that, optionally, the array structure of the flexible probe (2) is arranged to be stretched at a certain angle.

7. The novel passive flexible optical electrode according to claim 1 or 2, characterized in that, optionally, a layer of chitosan is laid on the flexible probe (2).

8 . The novel passive flexible optical electrode according to claim 1 or 2 , wherein, optionally, lead channels are established between the electrode groove structures, and the whole is an integrated design. 9 .