Active flexible dry electrode

Abstract

A flexible dry electrode (1) for measuring bioelectric signals of an individual, the electrode (1) comprising an electrode body (2), a connector side (11) with connection means (31) for attaching the electrode (1) to a support member, and a contact side (12) opposite the connector side (11) for contacting an area of interest of the individual when the electrode (1) is applied to the individual; wherein the electrode body (2) comprises a contact portion (4) of electrically conductive elastic material forming the contact side (12) of the electrode (1) and a connector portion (3) of electrically non-conductive material forming the connector side (11) of the electrode (1); wherein the electrode (1) further comprises a signal processing circuit (5) encapsulated between the connector portion (3) and the contact portion (4) of the electrode body (2), wherein the signal processing circuit (5) is electrically connected to the contact portion (4); and wherein the signal processing circuit (5) is provided with an electrical connector (51) penetrating the connector portion (3) on the connector side (11).

Description

Technical Field

[0001] This invention relates to an active flexible dry electrode (SDE) for detecting bioelectrical signals in applications such as electroencephalography (EEG), electrocardiography (ECG), or electromyography (EMG). Background Technology

[0002] So-called soft and dry electrodes (SDEs) typically consist of an electrode body made of a conductive elastomer, offering high wearing comfort due to the material's flexibility. Simultaneously, dry signal acquisition can be performed without the use of conductive gel, thus reducing preparation time and further improving wearing comfort. Therefore, SDEs are increasingly used for long-term electrobiopotential measurements.

[0003] The electrode body may have a connector side with connection means for attaching the electrode to a support member of a measuring device (e.g., a head-mounted device or other interface). Electrodes with suitable connection means are easily replaceable. The electrode can be placed on an individual's region of interest via the opposing contact sides to pick up biopotential signals. To transmit the signal from the individual to the measuring device, the electrode body may be made of or coated with a conductive material. Such flexible dry electrodes are known from WO2022047595.

[0004] To non-invasively capture an individual's potential fluctuations, two different electrode technology options are available: passive electrodes and active electrodes. Passive electrodes, such as those described in WO2022047595, are conventional electrodes that simply transmit voltage fluctuations from a conductive electrode to a signal processing unit via conductive wires. Active electrodes are electrodes that contain circuitry or components within or very close to their structure. Unlike conventional passive electrodes, active electrodes have built-in signal processing capabilities to improve the signal-to-noise ratio.

[0005] WO2020255142 describes a sensing system comprising several (active) electrodes. The sensing system includes a circuit board (e.g., a printed circuit board) and multiple flexible sensing legs (pins). The tip of each leg is electrically connected to the circuit board via a conductive portion. This sensing system has a fairly complex structure, and therefore its manufacture is complex.

[0006] US2019150838 describes an active EEG sensor. This EEG sensor includes an electrode body with several conductive legs. A snap-fit ​​connector is attached to the connector side of the sensor for attaching the sensor to a support device. The snap-fit ​​connector houses the active electrode circuitry / PCB. A disadvantage is that the PCB is separated from the actual electrodes, and a good signal-to-noise ratio depends on a tight connection between the snap-fit ​​connector and the actual electrodes.

[0007] US2020060571 describes an active electrode (sensor) for a head-mounted device, comprising a sensor body and an electronics board. The sensor body is made of a conductive polymer material and includes a disc-shaped substrate and a set of raised bumps. The electronics board is attached to the upper side of the sensor body via a cylindrical flange extending around the sensor body, the flange including a radially inward annular flange. This inward annular flange forms a recess for receiving the electronics board, which is intended to be held within the recess by the flange. The sensor body also includes a radially outward annular flange for mounting the sensor in a suitable recess in a support device. Because the sensor body simply slides across the PCB and is then secured in the support device, even slight bending of the sensor can cause an interruption or change in the electrical connection between the raised bumps and the electronics board.

[0008] WO2003079897 describes a disk-shaped active electrode. The electrode is encapsulated in an insulating layer that is resistive. The electrode has an internal conductive cap that acts as a shield and is "grounded," i.e., connected to a circuit reference potential that is connected to a reference electrode. Cables deliver power to onboard electronics and transmit signals from the onboard electronics. The circuitry is mounted on a two-layer printed circuit board with a bottom conductive layer that conveniently serves as a low-resistance ohmic contact with the electrode substrate. This substrate can be conductive rubber. The electrode has a rather complex structure, and the wire connections make efficient manufacturing difficult. Summary of the Invention

[0009] The objective of this invention is to design an active electrode that addresses the limitations of passive electrodes and improves the quality, reliability, and sensitivity of recorded signals while balancing usability and user comfort. Another objective is to avoid the drawbacks of known active electrodes, particularly by improving communication between the electrode and tissue through reduced noise and motion artifacts. Simultaneously, despite the integration of electronic components, the electrode design should be compact and cost-effective in manufacturing.

[0010] At least one object of the present invention is achieved by the flexible dry electrode according to claim 1 and the method of manufacturing such an electrode according to claim 15. The flexible dry electrode for measuring bioelectrical signals of an individual includes an electrode body, a connector side having a connection means for attaching the electrode to a support member, and a contact side opposite the connector side for contacting a region of interest of the individual when the electrode is applied to the individual. The electrode body includes a contact portion made of a conductive elastic material and a connector portion made of a non-conductive material, the contact portion forming the contact side of the electrode and the connector portion forming the connector side of the electrode. The electrode also includes a signal processing circuit encapsulated between the connector portion and the contact portion of the electrode body, wherein the signal processing circuit is electrically connected to the contact portion. The signal processing circuit is provided with an electrical connector that penetrates the connector portion on the connector side.

[0011] Therefore, the signal processing circuit can be securely encapsulated between two parts of the electrode body, which are made of different materials but firmly connected together. This electrode design can be manufactured cost-effectively by first molding the contact portion with a conductive rubber material. In the second step, the signal processing circuit is placed on the pre-molded contact portion, and then in the third step, the connector portion is overmolded with a non-conductive (rubber) material. This establishes a reliable electrical contact between the signal processing circuit and the underlying contact portion. The electrical connector of the signal processing circuit extends from the electrode body on the connector side and can be easily electrically contacted by another measuring device, while the electrode is attached to the support member via a separate connection device.

[0012] In use, the conductive contact portion of the electrode contacts the individual in the region of interest, transmitting the signal from the individual's tissue to an embedded or encapsulated signal processing circuit. The signal processing circuit preprocesses the detected signal, which is then further transmitted via an electrical connector to the main processing unit of an external measuring device. The connector portion electrically insulates the signal processing circuit and its electrical connector. It also provides a connection device for attaching the flexible dry electrode to a support structure.

[0013] In the context of this invention, conductivity or non-conductivity means having electrical conductivity or not having electrical conductivity, respectively. The support member can be a head-mounted device or any structure for placing electrodes on an individual. The support member may include or be connected to a measuring device or equipment. The signal processing circuit can be a signal processing unit comprising a printed circuit board (PCB) or flexible printed circuit board with or without surface-mount components. The signal processing circuit may or may not have a thin protective coating or shielding layer.

[0014] The connecting device is used to connect the electrodes to the support device in a stable but removable manner, while allowing for a degree of flexibility. The electrical connector is used to electrically connect the electrodes to the main measuring device. In some embodiments, the electrical connector can also be used as the connecting device.

[0015] The non-conductive material of the connector portion can be an elastic material. Therefore, the electrode body, including the connector portion and the contact portion, is made of an elastic material, which provides a uniform appearance and feel, and offers additional flexibility when combined with a flexible circuit board.

[0016] The elastic material of the electrode can be a thermosetting elastomer or a thermoplastic elastomer.

[0017] The elastic material can be, for example, synthetic or natural rubber, such as butyl rubber, isoprene rubber, butadiene rubber, halogenated butyl rubber (e.g., brominated butyl rubber), ethylene-propylene terpolymer, silicone rubber, fluorinated or perfluorinated elastomers, chlorosulfonates, polybutadiene, butyl rubber, chloroprene rubber, nitrile rubber, polyisoprene, nitrile rubber-N, copolymer rubbers such as ethylene-propylene (EPR), ethylene-propylene diene monomer (EPDM), acrylonitrile-butadiene (NBR or HNBR) and styrene-butadiene (SBR), blends such as ethylene or propylene-EPDM, EPR or NBR, or combinations thereof. The term “synthetic rubber” should also be understood to include materials that can be broadly classified as thermoplastic or thermosetting elastomers, such as polyurethanes, silicones, fluorosilicone rubbers, styrene-isoprene-styrene (SIS) and styrene-butadiene-styrene (SBS), as well as other polymers that exhibit rubber-like properties, such as plasticized nylons, polyolefins, polyesters, ethylene vinyl acetate, fluoropolymers, and polyvinyl chloride.

[0018] The electrical conductivity of elastic materials can be achieved by adding conductive materials. Conductive materials can be carbon black, silver-plated glass spheres, silver particles, silver-plated aluminum beads, silver-plated glass fibers, graphene, carbon nanotubes, graphite, stainless steel fibers, or any other suitable material.

[0019] Further embodiments of the present invention are set forth in the dependent claims.

[0020] In some embodiments, the connecting device is an integral part formed by the connector portion. The connecting device can be, for example, a snap-fit ​​connector for easily securing and removing electrodes from a support member having the corresponding connecting device. The snap-fit ​​connector can be in the form of a snap or button. Typically, the connecting device is arranged centrally on the connector side to better balance the electrodes and evenly distribute the applied force when the electrodes are applied to an individual. The connecting device is non-conductive and is not used for electrical contact with signal processing circuitry or contact portions.

[0021] In some embodiments, the signal processing circuit may have electrical contact devices, preferably pin connectors or point connectors, on the surface facing the contact portion to establish electrical contact between the signal processing circuit and the contact portion. Thus, the embedded signal processing circuit can receive signals from an individual, which are transmitted through the contact portion. The remaining surfaces of the signal processing circuit facing the contact portion are electrically insulated. Pin connectors can be pushed into the contact portion. Point connectors are conductive areas or points on the signal processing circuit / unit 5 that contact the surface of the contact portion.

[0022] In some embodiments, the electrical connector may be arranged on the connector side and spaced apart from the connecting device. The electrical connector may be a multi-pin connector, preferably a three-pin connector, which can be easily connected via standard wiring.

[0023] In some implementations, the connector portion and the contact portion can be connected to each other directly by covalent bonds or indirectly by adhesives. The material used for the electrode body can be a thermosetting (vulcanizable) material to provide chemical bonding between the connector portion and the contact portion.

[0024] In some embodiments, the contact side of the contact portion may have a plane or may be provided with a plurality of flexible contact pins for contacting the region of interest of the individual when the electrode is in use. The tips of the plane or contact pins may be provided with an additional conductive coating (e.g., an Ag / AgCl coating) to increase conductivity at the interface.

[0025] In some implementations, the signal processing circuitry may be a printed circuit board (PCB) or a flexible printed circuit board. The signal processing circuitry may include processing components such as amplifiers and / or digitizers.

[0026] In some embodiments, the contact portion and / or signal processing circuitry may be provided with positioning devices for positioning the signal processing circuitry at a defined position relative to the contact portion. The positioning device may be a protrusion on the contact portion that engages with an opening in the signal processing circuitry or the circuit board of the signal processing circuitry.

[0027] In some implementations, the contact portion and / or connector portion may have a circular shape.

[0028] In some embodiments, the contact portion may include a circumferential skirt projecting toward the connector side and / or the connector portion includes a circumferential skirt projecting toward the contact side. The circumferential skirt of one portion may abut and connect to the circumferential surface of the other portion. Alternatively, if both portions have circumferential skirts, the circumferential skirt of the connector portion may overlap with the circumferential skirt of the contact portion. In other words, the two skirts may overlap each other, thereby creating a larger surface area for a secure connection between the two portions.

[0029] In some embodiments, the side of the electrode body is formed by a connector portion that is not conductive.

[0030] In some implementations, flexible dry electrodes can be manufactured by injection molding, compression molding, injection transfer molding, or compression transfer molding.

[0031] The present invention also relates to a process for manufacturing the above-described flexible dry electrode. The process includes the following steps: (a.) molding a contact portion of a conductive elastomer; (b.) placing a signal processing circuit onto the pre-molded contact portion; and (c.) covering the formed signal processing circuit with a connector portion of a non-conductive material and thereby connecting the connector portion to the contact portion.

[0032] In some embodiments of the process, the connector portion and the contact portion may be made of a vulcanizable (thermosetting) material, wherein in step a), the contact portion may be only partially vulcanized or crosslinked, while in step c), the contact portion and the connector portion are fully vulcanized or crosslinked to form covalent bonds between them.

[0033] Therefore, a preferred process for manufacturing flexible dry electrodes may include the following steps. In the first step, the connector portion is injection molded. After molding, the injection molding tool is opened, with the connector portion remaining in the tool half on the contact side of the contact portion. In the second step, the signal processing circuit / unit is placed onto the contact portion. The signal processing circuit / unit can be positioned using a positioning device formed by the contact portion, for example, in the form of a protrusion that fits into the opening of the signal processing circuit / unit. In the third step, the mold is closed using another mold half that forms the cavity, so that the signal processing circuit / unit and the contact portion are encapsulated and molded using the connector portion.

[0034] Full vulcanization or crosslinking is understood as the degree of vulcanization or crosslinking required in the final product, rather than necessarily the degree of completeness that is chemically achievable.

[0035] In some implementations, the contact portion and connector portion are injection molded. Attached Figure Description

[0036] The invention will now be described in more detail with reference to the embodiments shown in the accompanying drawings. The drawings show:

[0037] Figure 1 This is a perspective view of the connector side of the flexible dry electrode;

[0038] Figure 2 yes Figure 1 A perspective view of the contact side of a flexible dry electrode;

[0039] Figure 3 yes Figure 1 Side view of the flexible dry electrode;

[0040] Figure 4 yes Figure 1 A cross-sectional view of the flexible dry electrode;

[0041] Figure 5 yes Figure 1 Exploded view of the flexible dry electrode;

[0042] Figure 6 This is a cross-sectional view of a variant of the flexible dry electrode;

[0043] Figure 7 This is a cross-sectional view of another variant of the flexible dry electrode. Detailed Implementation

[0044] Figures 1 to 5 A different view of a first embodiment of an active flexible dry electrode 1 (electrode or SDE) is shown. The flexible dry electrode 1 includes an elastic electrode body 2, which, in the illustrated embodiment, consists of two elastic portions 3 and 4, namely a connector portion 3 and a contact portion 4 firmly joined together. The connector portion 3 forms the connector side 11 of the electrode 1 and is made of a non-conductive elastomer material. The contact portion 4 forms the contact side 12 of the electrode 1 and is made of a conductive elastomer material. Such conductive elastomer materials are known in the art. In use, the contact portion 4 contacts the individual to pick up bioelectrical signals and transmit these signals to a signal processing circuit.

[0045] Figure 1 and Figure 2 These are perspective views of the connector side 11 and contact side 12 of electrode 1, respectively. Figure 3 A side view of the electrodes is shown. In the illustrated embodiment, the two parts 3 and 4 have a circular shape. Other shapes, such as elliptical or rectangular, may also be used.

[0046] The connector portion 3 is provided with a snap-on connection device 31. Such a connection device 31 is known in the art for attaching the electrode 1 to a corresponding connection device of the support device. In this embodiment, the snap is arranged in the center of the connector side 11 of the connector portion 3 to uniformly transmit pressure when the electrode is placed on the individual.

[0047] In the illustrated embodiment, the contact portion 4 is provided with a plurality of flexible contact pins 41, each having a conical base and a cylindrical end. When the electrode is applied to an individual, the contact pins 41 are flexible and can glide over hair (if present) to form appropriate contact with the individual.

[0048] An electrical connector 51 is also visible on the connector side 11 of the electrode 1 shown. In the illustrated embodiment, the electrical connector 51 is a three-pin connector. The electrical connector 51 is connected to the signal processing circuit 5 (in... Figure 4 (As shown in the diagram) and highlighting the connector portion 3 that passes through the electrode body 2. The pins of the electrical connector 51 can be contacted by a measuring device. In the illustrated embodiment, the electrical connector 51 is arranged next to the snap.

[0049] The active electrode also includes a signal processing circuit or unit 5, which is securely embedded or encapsulated between the connector portion 3 and the contact portion 4 of the elastic electrode body 2. Figure 4 A cross-sectional view of the flexible dry electrode 1 is shown. Figure 5 An exploded view of the flexible dry electrode 1 is shown. Figure 4 and Figure 5 In this diagram, the signal processing circuit or unit 5 is visible. The signal processing circuit / unit 5 is a printed circuit board (PCB) or flexible printed circuit board with or without surface mount components.

[0050] The signal processing circuit / unit 5 makes electrical contact with the contact portion 4 via an electrical contact device 53 (not shown). The electrical contact device 53 is located on a surface 54 on the contact side of the signal processing circuit / unit 5 and can be a pin connector or a point connector. A pin connector can be pushed into the contact portion 4. A point connector is a conductive area or point on the signal processing circuit / unit 5 that contacts the surface of the contact portion 4.

[0051] The connector portion 3 and the contact portion 4 of the electrode body 2 are firmly bonded together. This bonding can be achieved during manufacturing through an adhesive layer or through covalent bonding.

[0052] exist Figure 4 In one embodiment, the contact portion 4 is provided with a circumferential skirt 41 protruding in the direction toward the connector portion 3. The connector portion 3 is also provided with a circumferential skirt 31 protruding in the direction toward the contact portion 4. The circumferential skirt 31 of the connector portion 3 has a larger diameter than the circumferential skirt 41 of the contact portion 4 and forms the outer surface of the electrode 1. With this structure, compared with the other two embodiments described below ( Figure 6 and Figure 7 Compared to the previous version, the connection area between these two parts is increased.

[0053] Figure 6 A cross-sectional view of a variant of the flexible dry electrode is shown. In this embodiment, only the connector portion 3 is provided with a circumferential skirt 31. Figure 7 A cross-sectional view of another variant of the flexible dry electrode is shown. In this embodiment, only the contact portion 4 is provided with a circumferential skirt 41. Figure Labels

[0054] 1. Flexible dry electrode (SDE)

[0055] 11 Connector side

[0056] 12 Contact side

[0057] 2 Electrode Body

[0058] 3 Connector Section

[0059] 31 Connecting device

[0060] 33-inch flared skirt hem

[0061] 4. Contact area

[0062] 41 Flexible contact needle

[0063] 42 Positioning device

[0064] 43. Circumferential hem

[0065] 5. Signal Processing Circuits / Units

[0066] 51 Electrical Connector

[0067] 52 Positioning device

[0068] 53 Electrical contact devices

[0069] 54 Surface on the contact side

Claims

1. A flexible dry electrode (1) for measuring bioelectrical signals of an individual, the electrode (1) comprising an electrode body (2). The connector side (11) has a connecting device (31) for attaching the electrode (1) to the support member, and A contact side (12) opposite to the connector side (11) is used to contact the region of interest of the individual when the electrode (1) is applied to the individual; Its features The electrode body (2) includes a contact portion (4) made of a conductive elastic material and a connector portion (3) made of a non-conductive material. The contact portion (4) forms the contact side (12) of the electrode (1), and the connector portion (3) forms the connector side (11) of the electrode (1). The electrode (1) further includes a signal processing circuit (5) encapsulated between the connector portion (3) and the contact portion (4) of the electrode body (2), wherein the signal processing circuit (5) is electrically connected to the contact portion (4). Furthermore, the signal processing circuit (5) is provided with an electrical connector (51), which penetrates the connector portion (3) on the connector side (11).

2. The flexible dry electrode according to claim 1, wherein the connecting device (31) is an integral part formed by the connector portion (3).

3. The flexible dry electrode according to any one of the preceding claims, wherein the connecting device (31) is formed as a snap connector, preferably in the form of a snap or button.

4. The flexible dry electrode according to any one of the preceding claims, wherein the signal processing circuit (5) is provided with an electrical contact device (53), preferably a pin connector or a point connector, on a surface (54) facing the contact portion (4) for establishing an electrical contact between the signal processing circuit (5) and the contact portion (4).

5. The flexible dry electrode according to any one of the preceding claims, wherein the electrical connector (51) is arranged on the connector side (11) and spaced apart from the connection device (31).

6. The flexible dry electrode according to any one of the preceding claims, wherein the connector portion (3) and the contact portion (4) are connected to each other directly by covalent bonds or indirectly by adhesive.

7. The flexible dry electrode according to any one of the preceding claims, wherein the contact side (12) of the contact portion (4) has a plane or is provided with a plurality of flexible contact pins (41).

8. The flexible dry electrode according to any one of the preceding claims, wherein the signal processing circuit (5) is a printed circuit board or a flexible printed circuit board.

9. The flexible dry electrode according to any one of the preceding claims, wherein the contact portion (4) and / or the signal processing circuit (5) are provided with positioning devices (42, 52) for positioning the signal processing circuit (5) at a defined position relative to the contact portion (4).

10. The flexible dry electrode according to any one of the preceding claims, wherein the contact portion (4) and / or the connector portion (3) has a circular shape.

11. The flexible dry electrode according to any one of the preceding claims, wherein the contact portion (4) includes a circumferential skirt (43) protruding toward the connector side (11) and / or the connector portion (3) includes a circumferential skirt (33) protruding toward the contact side (12).

12. The flexible dry electrode according to any one of the preceding claims, wherein the circumferential skirt of the connector portion overlaps with the circumferential skirt of the contact portion.

13. The flexible dry electrode according to any one of the preceding claims, wherein the side surface of the electrode body (2) is formed by a connector portion (3) that is not conductive.

14. The flexible dry electrode according to any one of the preceding claims, wherein the connector portion (3) is made of a non-conductive material.

15. A process for manufacturing a flexible dry electrode according to any one of the preceding claims, the process comprising the following steps: a. Molding the contact portion (4); b. Place the signal processing circuit (5) onto the pre-molded contact portion (4); c. The signal processing circuit (5) is overmolded with the connector portion (3) and thereby the connector portion (3) is connected to the contact portion (4).

16. The process according to claim 15, wherein the connector portion (3) and the contact portion (4) are made of a vulcanizable material, wherein in step a), the contact portion (4) is only partially vulcanized or crosslinked, and in step c), the contact portion (4) and the connector portion (3) are fully vulcanized or crosslinked to form covalent bonds between them.

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