Soft dry electrode

Abstract

A flexible electrode (1) for measuring a bioelectrical signal of an individual, the electrode (1) comprising a support (2) having a contact side (21) facing the individual when the electrode (1) is applied to the individual and a connector side (22) opposite the contact side (21), the support (2) further defining a central axis (A) centrally disposed through the contact side (21) and the connector side (22), the electrode (1) further comprising a plurality of external contact pins (3) located in a radially outer region (23) of the support (2) for contacting a region to be measured, the plurality of external contact pins (3) being supported and arranged on the contact side (21) of the support (2), the electrode (1) being made of an elastomeric material and having conductive properties. The support (2) has a dome-like shape with a concave side (21a) and a convex side (22b), the concave side (21a) forming the contact side (21) of the support (2), and the support (2) is designed with flexibility such that after application of the electrode to an individual, a force exerted centrally toward the connector side (22) and parallel to the central axis (A) causes the radial outer region (23) of the support (2) to bend upward toward the connector side (22), which causes the multiple external contact pins (3) to tilt relative to the central axis (A) so that the tips (31) of the external contact pins (3) move radially outward along the target area of ​​the individual.

Description

Technical Field

[0001] The present invention relates to a soft and dry electrode for detecting bioelectric signals in applications such as electroencephalogram (EEG) examination, electrocardiogram (ECG) examination, or electromyogram (EMG) examination.

Background Art

[0002] Since commercially available "dry" EEG headsets often have metal dry electrodes, subjects feel pain when wearing the headset for a while. A possible solution is to combine such electrodes with a spring-like system to avoid high skin pressure.

[0003] Yet another approach is the use of soft polymer-based dry electrodes. By mixing an elastic polymer with an additive, conductivity can be improved while maintaining the elasticity required for high user comfort. Polymer-based dry electrodes can have a comb-like design (finger or leg portions) to improve skin contact on hairy skin (e.g., the scalp). Such finger or leg portions can have at least a partial coating on the surface of the electrode in contact with the skin to reduce skin impedance and provide improved signal quality.

[0004] Therefore, soft and dry electrodes are being used even more for long-term biopotential measurements such as EEG and ECG. In addition to being soft, the additional fact that such electrodes can be applied without using a conductive gel gives the measurement procedure several advantages such as a reduced risk of skin irritation and avoidance of signal quality degradation due to gel drying.

[0005] Examples of such flexible dry electrodes are described in "Polymer-based dry electrodes for user-comfortable ECG / EEG measurements" by Chen et al. (Chen, Yun-Hsuan; Op de Beeck, Maaike; Carrette, Evelien; Vanderheyden, Luc; Grundlehner, Bernard; Mihajlovic, Vojkan; Boon, Paul; Van Hoof, Chris; Apprimus Verlag; Aachen; 8th International Conference and Exhibition on Integration Issues of Miniaturized Systems - MEMS, NEMS, ICs and Electronic Components; 2014; pp. 329-336), and also in "Flexible and comfortable polymer dry electrodes for high-quality ECG and EEG recording" by Chen et al. (Sensor 2014, 14, 23758-23780; doi:10.3390 / s141223758) or WO2016080804.

[0006] These flexible dry electrodes comprise a substrate and a number of pins for contacting the area to be measured. The pins may have tapered and projection portions. The electrode tips are made of a flexible or soft matrix material with a conductive material provided. The electrodes may have a knob on the upper side of the substrate opposite the pins for electrically connecting the electrodes.

[0007] When force is applied to a soft electrode (e.g., by a strap, band, headset, or head cap), the leg portion may move uncontrollably, failing to provide the intended brushing function for moving hair to the side and potentially causing direct contact between the electrode and the skin surface.

[0008] One possible solution to this problem is the pre-orientation of the electrodes (as described in EP2827770) such that when the electrodes are applied to the area of ​​interest (e.g., the scalp), the electrodes are positioned at a non-perpendicular angle to that area. However, a drawback of this method is the manufacturing process employed, which involves a 3D printing step that is not suitable for scaling up for mass production.

[0009] JP20190977332 relates to electrodes for measuring brain activity. The electrodes have a rigid support and several arms attached to the sides of the rigid support. A bulb is formed at the end of the arms to contact the human scalp. The arms are flexible and bend when force is applied to the electrodes. Because the electrodes have a complex shape with several notches, they are difficult to manufacture in a cost-effective manner. [Overview of the Initiative] [Problems that the invention aims to solve]

[0010] The objective of the present invention is to provide a flexible electrode for measuring the bioelectrical signals of an individual, which avoids the problems of the prior art and is suitable for mass production. [Means for solving the problem]

[0011] At least one of the objectives is achieved by a flexible electrode for measuring the bioelectrical signals of an organism as described in claim 1. The flexible electrode comprises a support having a contact side that faces the organism when the electrode is applied to the organism, and a connector side opposite to the contact side. The connector side serves to connect the electrode to an electronic circuit. The support defines a central axis that is located in the center through the contact side and the connector side. The electrode further comprises a plurality of external pins located in the radially outer region of the support to contact the area to be measured. The plurality of external pins are supported and positioned on the contact side of the support. The electrode is made of an elastomer material and has conductive properties. The support has a dome-like shape with a concave side and a convex side, the concave side forming the contact side of the support. The support is designed to be flexible such that, after the electrode is applied to the organism, a force applied centrally to the connector side and parallel to the central axis causes the radially outer region of the support to bend upward toward the connector side. Bending the radially outer region of the support upward leads to tilting multiple external contact pins with respect to the central axis so that the tips of the external contact pins move radially outward along the target area of ​​the individual.

[0012] In other words, when force is applied to the upper surface of the support, the flexible support begins to bend so that the tips of the pins or legs move outward (i.e., away from the center of the electrode) to "brush aside" any hair that is preventing direct contact between the electrode and the exposed skin surface of the individual being measured. Furthermore, the use of elastomer materials, such as thermosetting elastomers or thermoplastic elastomers (TPEs), and the dome-like shape of the support with multiple pins parallel to the central axis of the support enable production methods such as injection molding, compression molding, injection transfer molding, and injection compression molding. These types of production methods enable mass production of electrodes.

[0013] Further embodiments of the present invention are described in the dependent claims.

[0014] In some embodiments, the vertical axis of each of the multiple external pins is parallel to the central axis.

[0015] In some embodiments, the electrodes may further include a plurality of internal contact pins located in the internal region of the support closer to the central axis than in the external region of the support, and sized to contact the solid after tilting of the external contact pins occurs.

[0016] In some embodiments, the multiple external contact pins and the multiple internal contact pins may have the same length. Alternatively, the multiple external contact pins and the multiple internal contact pins may have different lengths, preferably the internal contact pins being shorter than the external contact pins. For example, pins located in a more central region of the electrode may be shorter so that they only begin to touch the skin surface (e.g., scalp) when the external pins are tilted outward to prepare the exposed skin that these central pins will touch.

[0017] In some embodiments, the multiple external contact pins and multiple internal contact pins may be arranged and sized such that the multiple external contact pins contact the area of ​​interest in front of the multiple internal contact pins while the electrodes are being applied to the solid.

[0018] In some embodiments, multiple external contact pins and / or multiple internal contact pins may have a conical base and a cylindrical free end. The free end forms the tip of the pin.

[0019] In some embodiments, the support may be a dome-shaped disk, preferably a circular disk. The disk in the sense of the present invention may have a semicircular shape such as an ellipse or polygon, for example, a triangle, pentagon or hexagon.

[0020] In some embodiments, the support may comprise a central disk, preferably a circular disk, having a plurality of legs that are radially outward at an angle of less than 90 degrees, preferably 30 to 70 degrees, with respect to the central axis, and that define the outer region of the dome-shaped support. Here, a plurality of external contact pins are located at the free ends of the legs.

[0021] In some embodiments, the connector side of the support may be provided with a knob, or so-called male snap fit, for electrically connecting the electrodes to an electronic circuit. The knob or male snap fit may be made of the same soft conductive material as the electrodes or a rigid material (e.g., metal, plastic) to facilitate connection to the electronic circuit.

[0022] In some embodiments, the tips of the multiple external contact pins may have inclined surfaces facing toward the central axis of the support.

[0023] In some embodiments, the connector side of the support may be provided with slits or grooves surrounding the base of the contact pins in order to increase the flexibility of the support.

[0024] In some embodiments, the electrode elastomer material may be a thermosetting elastomer or a thermoplastic elastomer.

[0025] Examples of elastomeric materials include, for example, synthetic or natural rubbers such as butyl rubber, isoprene rubber, butadiene rubber, halogenated butyl rubber (e.g., bromobutyl rubber), ethylene propylene terpolymer, silicone rubber, fluorinated or perfluoroelastomers, chlorosulfonic acid, polybutadiene, butyl, neoprene, nitrile, polyisoprene, buna N, copolymers of ethylene - propylene (EPR), etc., ethylene - propylene - diene monomer (EPDM), acrylonitrile - butadiene (NBR or HNBR) and styrene butadiene (SBR), blends of ethylene or propylene - EPDM, EPR, or NBR, etc., or combinations thereof. The term "synthetic rubber" may also alternatively be broadly classified to include other polymers that exhibit rubber - like properties such as thermoplastic or thermosetting elastomers, e.g., polyurethane, silicone, fluorosilicone, styrene - isoprene - styrene (SIS), and styrene - butadiene - styrene (SBS), as well as plasticized nylon, polyolefin, polyester, ethylene vinyl acetate, fluoropolymer, and other polymers such as polyvinyl chloride.

[0026] Good results may be achieved with ethylene propylene diene monomer (EPDM), silicone rubber (SR), liquid silicone rubber (LSR), butyl rubber, isoprene or nitrile rubber.

[0027] In some embodiments, the conductive properties of the electrode may be achieved by adding a conductive material to the elastomeric material. The conductive material may be carbon black, glass spheres coated with silver, silver particles, aluminum beads coated with Ag, glass fibers coated with Ag, graphene, carbon nanotubes, graphite, stainless steel fibers, or any other suitable material. The conductive properties of the electrode may also be achieved by coating the electrode with a conductive material, e.g., Ag - AgCl or PEDOT:PSS.

[0028] In some embodiments, the coating may be applied in addition to the conductive elastomer material. Such additional coating may be applied only on the tip of the pin.

[0029] In some embodiments, the electrode may be formed as a single piece.

[0030] The present invention will be described in more detail below with reference to the embodiments shown in the figures. The figures show the following.

Brief Description of the Drawings

[0031] [Figure 1] Bottom view (a), side view (b), and perspective view (c) of an electrode having a circular disk in the shape of a dome. [Figure 2] Cross-sectional views of the electrode of FIG. 1 before (a) and after (b) applying force to the electrode. [Figure 3] Bottom view (a), side view (b), and perspective view (c) of an electrode having a support in the shape of a dome with legs. [Figure 4] Cross-sectional views of the electrode of FIG. 3 before (a) and after (b) applying force to the electrode.

Mode for Carrying Out the Invention

[0032] FIG. 1 shows a bottom view (a), a side view (b), and a perspective view (c) of a soft dry electrode 1 for measuring a bioelectrical signal of an individual. FIG. 2 shows cross-sectional views of the electrode of FIG. 1 before (a) and after (b) applying force to the electrode.

[0033] Electrode 1 is made of an elastomer material that is provided with a conductive additive and / or at least partially coated with a conductive coating. Electrode 1 is formed as a single piece and comprises a dome-shaped support 2, several external contact pins 3, and several internal contact pins 4. The support 2 forms a concave contact side 21 that supports the contact pins 3, 4 for contacting a solid, and a convex connector side 22 opposite to the contact side 21. The connector side 22 is provided with a connector knob 28 for electrically connecting electrode 1 to an electronic circuit. The support 2 defines a central axis A located in the middle, passing through the contact side 21 and the connector side 22.

[0034] The support body 2 supports a plurality of external pins 3 arranged in the radial outer periphery region 23 of the support body 2. The central axis P of each pin 3 is parallel to the central axis A of the support body. In other words, when the electrodes are applied to a solid, the pins 3 touch the contact area of ​​the solid perpendicular to the contact area.

[0035] The dome-shaped support 2 has flexibility such that its radially outer region 23 bends upward (i.e., away from the body) when a force is applied parallel to the central axis A of the support 2 towards the center of the connector side 22 of the electrode 1. As a result, each outer pin 3 begins to tilt as force is applied to the connector side 22 of the electrode 1, and the tip 31 of each outer pin 3 slides radially outward along the body's skin, thereby brushing through any hair present. This increases the contact of the electrode with the body. To increase the rigidity of each outer pin 3, it may have a conical base and a cylindrical tip.

[0036] The electrodes shown in Figures 1 and 2 further include an inner pin 4. The outer and inner pins 3 and 4 have the same length such that the tip 41 of the inner pin 4 is offset along the central axis A toward the connector side 22. This ensures that while electrode 1 is applied to the object, the outer pin 3 first makes contact with the contact area of ​​the object.

[0037] To facilitate sliding movement on the skin, the free end of the pin may be rounded or provided with an inclined surface facing toward the central axis of the support.

[0038] Figure 3 shows a bottom view (a), a side view (b), and a perspective view (c) of a further embodiment of the soft, dry electrode 1 for measuring bioelectrical signals of an organism. Figure 4 shows cross-sectional views of the electrode in Figure 3 before (a) and after (b) force is applied to the electrode.

[0039] In contrast to the electrode 1 in Figure 1, the support 2 of the electrode 1 in Figure 3 comprises a central circular disk 26 and a plurality of legs 27. The legs 27 are evenly arranged circumferentially at an angle of less than 90 degrees, preferably 30 to 70 degrees, with respect to the central axis A, and are directed radially outward. The legs 27 define the external region 23 of the dome-shaped support 2. A plurality of external contact pins 3 are located at the free ends of the legs 27. In the illustrated embodiment, there are no internal pins. Alternatively, there may be internal pins that only contact the solid after the legs begin to bend.

[0040] As force is applied to electrode 1, the outer tips of the legs 27 that form the outer region 23 of the support 2 move upward in the direction of the connector side 23, that is, almost parallel to the central axis A. As a result, the outer pins 3 tilt, and the tips 31 of each outer pin 3 move outward, radially away from the central axis A, and slide along the skin of the individual. [Explanation of symbols]

[0041] 1 electrode 2 Support 21 Contact side of the support 21a Concave side 22 Connector side of the support 22a Convex side 23 External area of ​​the support 24 Internal region of the support 25. Dome-shaped circular disc 26 Central circular disk 27 Legs 28 snacks 3 External contact pins 31 Tip of external contact pin 4 Internal contact pins 41 Tip of internal contact pin A center axis P pin shaft

Claims

1. A soft electrode (1) for measuring the bioelectrical signals of an individual, When the electrode (1) is applied to the individual, the contact side (21) facing the individual, The support (2) comprises a connector side (22) opposite to the contact side (21), The support (2) further defines a central axis (A) located in the center, passing through the contact side (21) and the connector side (22), The electrode (1) further comprises a plurality of external contact pins (3) located in the radially outer region (23) of the support (2) in order to contact the measurement target range. The plurality of external contact pins (3) are supported and arranged on the contact side (21) of the support (2), The electrode (1) is a soft electrode (1) made of an elastomer material and having conductive properties, The support (2) is a dome-shaped disk having a concave side (21a) and a convex side (22b), the concave side (21a) forming the contact side (21) of the support (2), The support (2) is designed to be flexible such that, after the electrodes are applied to the solid, a force applied to the connector side (22) centrally and parallel to the central axis (A) causes the radially outer region (23) of the dome-like disk (2) to bend upward toward the connector side (22). A soft electrode (1) characterized in that bending the radially outer region (23) of the dome-like disk (2) upward leads to tilting the plurality of external contact pins (3) with respect to the central axis (A) such that the tips (31) of the external contact pins (3) move radially outward along the target range of the individual.

2. The soft electrode according to claim 1, characterized in that the vertical axis (P) of each of the plurality of external contact pins (3) is parallel to the central axis (A).

3. The soft electrode according to claim 1 or 2, wherein the electrode (1) further comprises a plurality of internal contact pins (4), which are located in an internal region (24) of the support (2) that is closer to the central axis (A) than the external region (23) of the support (2), and are sized to contact the solid after the external contact pins (3) have been tilted.

4. The soft electrode according to claim 3, characterized in that the plurality of external contact pins (3) and the plurality of internal contact pins (4) have the same length.

5. The flexible electrode according to claim 3 or 4, characterized in that the plurality of external contact pins (3) and the plurality of internal contact pins (4) are arranged and sized such that the plurality of external contact pins (3) contact the target area in front of the plurality of internal contact pins (4) while the electrode (1) is applied to the solid.

6. The soft electrode according to any one of claims 3 to 5, characterized in that the plurality of internal contact pins (4) have a conical base and a cylindrical free end.

7. The flexible electrode according to any one of claims 1 to 6, characterized in that the plurality of external contact pins (3) each have a conical base and a cylindrical free end.

8. The soft electrode according to any one of claims 1 to 7, characterized in that the support (2) is a circular disk (25).

9. The flexible electrode according to any one of claims 1 to 8, characterized in that a knob (28) for electrically connecting the electrode (1) to an electronic circuit is provided on the connector side (22) of the support (2).

10. The soft electrode according to any one of claims 1 to 9, characterized in that the tips (31) of the plurality of external contact pins (3) have inclined surfaces facing toward the central axis (A) of the support (2).

11. The soft electrode according to any one of claims 1 to 10, characterized in that the elastomer material of the electrode (1) is a thermosetting elastomer or a thermoplastic elastomer.

12. The soft electrode according to any one of claims 1 to 11, characterized in that the electrode is formed as an integral molding.

13. A soft electrode (1) for measuring the bioelectrical signals of an individual, The electrode (1) is When the electrode (1) is applied to the individual, the contact side (21) facing the individual, The support (2) comprises a connector side (22) opposite to the contact side (21), The support (2) further defines a central axis (A) located in the center, passing through the contact side (21) and the connector side (22), The electrode (1) further comprises a plurality of external contact pins (3) located in the radially outer region (23) of the support (2) in order to contact the measurement target range. The plurality of external contact pins (3) are supported and positioned on the contact side (21) of the support (2). The electrode (1) is a soft electrode (1) made of an elastomer material and having conductive properties, The support (2) has a dome-like shape with a concave side (21a) and a convex side (22b), and the concave side (21a) forms the contact side (21) of the support (2). The support (2) is designed to be flexible such that, after the electrode is applied to the solid, a force applied towards the connector side (22) towards the center and parallel to the central axis (A) causes the radially outer region (23) of the support (2) to bend upward toward the connector side (22). Bending the radially outer region (23) of the support (2) upward results in tilting the plurality of external contact pins (3) with respect to the central axis (A) such that the tips (31) of the external contact pins (3) move radially outward along the target area of ​​the individual, The soft electrode is characterized in that the support (2) comprises a central disk having a plurality of legs (27) that are radially outward at an angle of less than 90 degrees with respect to the central axis (A) and define the outer region (23) of the dome-shaped support (2), the plurality of external contact pins (3) are arranged at the free ends of the legs (27), and the longitudinal axis (P) of each of the plurality of external contact pins (3) is parallel to the central axis (A).

14. The soft electrode according to claim 13, characterized in that the angle with respect to the central axis (A) is between 30 and 70 degrees.

15. The flexible electrode according to claim 13 or 14, characterized in that the plurality of external contact pins (3) have a conical base and a cylindrical free end.

16. The soft electrode according to claim 13 or 15, characterized in that the tips (31) of the plurality of external contact pins (3) have inclined surfaces facing the central axis (A) of the support (2).

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