Biological electrodes

Abstract

Provided is a biological electrode capable of suppressing the front end side portion of the electrode portion in contact with the subject's body from bending in the opposite direction (inward) of the expansion direction. The biological electrode (1) includes an electrode component (20) made of conductive rubber having a plurality of electrode portions (22) in contact with the subject's body. The plurality of electrode portions (22) are protrudingly formed on the electrode portion forming surface (21b) of the electrode component (20) and are arranged in a circular or concentric circle shape on the electrode portion forming surface (21b). In addition, the plurality of electrode portions (22) are respectively formed so that the cross-sectional area gradually decreases from the base portion toward the front end portion, and when observed from the configuration center of the plurality of electrode portions (22), the cross-sectional center (C2) of the front end portion is located radially outward relative to the cross-sectional center (C1) of the base portion.

Description

Technical Field

[0001] The present invention relates to a biological electrode, and in particular to a biological electrode suitable for detecting brain waves. Background Art

[0002] As an example of such a bioelectrode, the bioelectrode described in Patent Document 1 is known. The bioelectrode described in Patent Document 1 comprises an electrode component that contacts the subject's body and a conductive support component that supports the electrode component. At least the electrode component is made of conductive rubber containing silicone rubber and silver powder. In the bioelectrode described in Patent Document 1, multiple electrode components are arranged so as to protrude from the support component in a brush-like manner.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: International Publication No. 2018 / 230445. Summary of the Invention

[0006] Technical problem to be solved by the invention

[0007] Most biological electrodes used in the past for electroencephalogram detection have multiple electrode parts (equivalent to the electrode components in Patent Document 1), and the front end of each electrode part part the subject's hair and contacts the subject's scalp, thereby enabling electroencephalogram detection.

[0008] For example, when measuring EEG waves in subjects with thick hair, strong pressure must be applied to the bioelectrodes to prevent the distal end of each electrode from coming into contact with the subject's scalp due to the hair. Repeated application of such strong pressure to the bioelectrodes can cause the distal end of each electrode to deform. In particular, if the distal end of the electrode bends in the direction opposite to the direction of expansion (inward), it becomes difficult to maintain stable contact between the distal end of the electrode and the subject's scalp, potentially hindering EEG detection.

[0009] Such a possibility is not limited to the case of detecting electroencephalograms, but is generally present when a biological signal is detected by bringing the distal end portion of the electrode into contact with the body (skin) of a subject.

[0010] Therefore, an object of the present invention is to provide a biological electrode capable of preventing the distal end portion of the electrode portion in contact with the subject's body from bending in the direction opposite to the expansion direction (inward).

[0011] Means for solving technical problems

[0012] According to one aspect of the present invention, a biological electrode includes an electrode component made of conductive rubber, wherein the conductive rubber electrode component has a plurality of electrode portions that contact the subject's body. The plurality of electrode portions are formed protruding from the electrode portion forming surface of the electrode component and are arranged in a circular or concentric circle shape on the electrode portion forming surface. In addition, the plurality of electrode portions are each formed so that the cross-sectional area gradually decreases as the electrode portion approaches the front end portion, and when viewed from the center of the arrangement of the plurality of electrode portions, the cross-sectional center of the front end portion is located radially outward relative to the cross-sectional center of the base portion.

[0013] According to another aspect of the present invention, a biological electrode includes a supporting part, an electrode part made of conductive rubber, and a connector for electrically connecting the electrode part to the outside. The electrode part includes: a supported part supported by the supporting part; and a plurality of electrode parts protruding from the supported part to the opposite side of the supporting part and in contact with the subject's body. The connector is constructed so that a portion is buried in the supported part of the electrode part and extends through the supporting part, and the connection part with the outside is located on the surface of the supporting part on the opposite side of the electrode part. The plurality of electrode parts are arranged in a circular or concentric shape on the electrode part forming surface of the supported part. In addition, the plurality of electrode parts are respectively formed so that the cross-sectional area gradually becomes smaller from the base part to the front end part, and when viewed from the configuration center of the plurality of electrode parts, the cross-sectional center of the front end part is located radially outward than the cross-sectional center of the base part.

[0014] Effects of the Invention

[0015] According to the present invention, it is possible to provide a biological electrode capable of suppressing the distal end portion of the electrode portion in contact with the subject's body from bending in the direction opposite to the expansion direction (inward). BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a front view of a biological electrode according to one embodiment of the present invention.

[0017] Figure 2 This is a bottom view of the biological electrode.

[0018] Figure 3 yes Figure 1 AA cross-sectional view.

[0019] Figure 4 This is a longitudinal sectional view (enlarged view) of the electrode portion of the biological electrode.

[0020] Figure 5 FIG. 1 is a diagram showing a biological electrode according to another embodiment of the present invention. Figure 5 (a) is the main view, Figure 5(b) is a bottom view.

[0021] Figure 6 This is a diagram showing another shape of the electrode portion of the biological electrode (equivalent to Figure 4 (Figure ). DETAILED DESCRIPTION

[0022] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

[0023] Figure 1 1 is a front view of a biological electrode 1 according to an embodiment of the present invention. Figure 2 is a bottom view of the biological electrode 1, Figure 3 yes Figure 1 AA section view of the Figures 1 to 3 As shown, a biological electrode 1 according to an embodiment includes a support member 10; an electrode member 20 made of conductive rubber, supported by the support member 10; and a connector 30 for electrically connecting the electrode member 20 to the outside. The electrode member 20 has a supported portion 21 supported by the support member 10; and a plurality of electrode portions 22 protruding from the supported portion 21 toward the side opposite the support member 10.

[0024] By bringing the front end portions of the multiple electrode portions 22 of the electrode component 20 into contact with the subject's body (skin), the biological electrode 1 can detect (read out) the subject's biological signals via the connector 30. The biological electrode 1 is used, for example, as a biological electrode for measuring brain waves. In this case, the biological electrode 1 is placed on the subject's head in a manner such that the front end portions of the multiple electrode portions 22 are in contact with the subject's scalp. However, this is not limited to this. The biological electrode 1 can also be used to detect biological signals other than brain waves.

[0025] In the biological electrode 1, the support member 10 is formed of an electrically insulating material (e.g., silicone rubber). In this embodiment, the support member 10 is formed in a disk shape. The support member 10 has a support surface 10a for supporting the electrode member 20 and a back surface 10b opposite to the support surface 10a. In addition, a through hole 10c (see FIG. 1 ) is formed in the center portion of the support member 10, which passes through the support member 10 in the thickness direction (i.e., from the support surface 10a to the back surface 10b). Figure 3 ).

[0026] In addition, the support member 10 only needs to have structures corresponding to the support surface 10 a , the back surface 10 b , and the through-hole 10 c , and does not necessarily need to be formed in a disk shape.

[0027] In the biological electrode 1, the electrode part 20 is formed of a conductive rubber and has, as described above, a supported portion 21 supported by the supporting portion 10 and a plurality of electrode portions 22 protruding from the supported portion 21 to the opposite side of the supporting portion 10. In the present embodiment, the conductive rubber is a so-called conductive silicone rubber containing silicone rubber and metal particles. The silicone rubber is, for example, a room temperature curing liquid silicone rubber, and the metal particles are, for example, silver particles. The room temperature curing liquid silicone rubber refers to a silicone rubber that is in a liquid or paste state before curing and undergoes a curing reaction at 20°C to 100°C to become a rubber elastic body. The silver particles may include agglomerated particles (agglomerates) in which a plurality of silver particles (primary particles) are adhered, or flaky silver particles.

[0028] Furthermore, the conductive rubber forming the electrode member 20 may contain other conductive metal particles or carbon-based material particles (carbon black, carbon nanotubes, etc.) instead of silver particles, and may also contain reinforcing materials, fillers, and various additives as appropriate.

[0029] The supported portion 21 of the electrode member 20 has the same shape as the supporting member 10. That is, in this embodiment, the supported portion 21 is formed into a disk shape. The supported portion 21 has a supported surface 21a supported by the supporting surface 10a of the supporting member 10 and an electrode portion forming surface 21b opposite to the supported surface 21a.

[0030] A plurality of electrode portions 22 are formed protruding from the electrode portion forming surface 21b of the supported portion 21. The plurality of electrode portions 22 are arranged in a concentric circle shape on the electrode portion forming surface 21b. Specifically, the plurality of electrode portions 22 are arranged on the circumference of two imaginary concentric circles (hereinafter referred to as "concentric circles") 23 and 24 on the electrode portion forming surface 21b. In addition, the plurality of electrode portions 22 are respectively formed so that the cross-sectional area gradually decreases as they approach the front end portion from the base portion (root) (in other words, away from the electrode portion forming surface 21b).

[0031] Specifically, in this embodiment, each of the plurality of electrode portions 22 has a circular cross-section, with the diameter gradually decreasing from the base portion toward the tip portion. Furthermore, the cross-sectional center C1 of the base portion of each of the plurality of electrode portions 22 is arranged so as to lie on the circumference of either concentric circle 23 or 24 (not necessarily strictly on the circumference, but only approximately on the circumference).

[0032] The front end portion of each of the plurality of electrode portions 22 is formed into a hemispherical shape. In addition, the plurality of electrode portions 22 are formed so that, when viewed from the configuration center O of the plurality of electrode portions 22 (i.e., the center of the concentric circles 23, 24), the center of the front end portion (also referred to as the cross-sectional center of the front end portion) C2 is located radially outward relative to the cross-sectional center C1 of the base portion. That is, in this embodiment, the plurality of electrode portions 22 each have an oblique conical shape with a rounded apex. In addition, Figure 3 The symbol OL in denoted by refers to the center line of the concentric circles 23 and 24 and indicates a perpendicular line passing through the electrode portion forming surface 21 b at the arrangement center O.

[0033] Furthermore, in this embodiment, the plurality of electrode portions 22 are arranged at equal intervals (not necessarily strictly equal intervals, but substantially equal intervals) in the circumferential direction. Specifically, the plurality of electrode portions 22 are arranged at equal intervals on the circumference of either of the concentric circles 23 and 24 .

[0034] Figure 4 This is a longitudinal sectional view (enlarged view) of the electrode portion 22 cut along a plane including a perpendicular line OL passing through the electrode portion forming surface 21b of the configuration center O (i.e., the center line of the concentric circles 23, 24). Figure 4 As shown, in each of the multiple electrode parts 22, the imaginary straight line X connecting the cross-sectional center C1 of the base part and the cross-sectional center C2 of the front end part is inclined in such a manner that the closer it is to the front end part, the farther it is away from the perpendicular line OL of the electrode part forming surface 21b passing through the configuration center O (the center line of the concentric circles 23 and 24).

[0035] Furthermore, in this embodiment, in each of the plurality of electrode portions 22, the generatrix B1 located farthest from the arrangement center O is perpendicular to the electrode portion forming surface 21b. Meanwhile, the generatrix B2 located closest to the arrangement center O of the plurality of electrode portions 22 is inclined so as to become increasingly distant from the perpendicular line OL passing through the electrode portion forming surface 21b, which passes through the arrangement center O, as it approaches the tip from the base portion. The term "perpendicular" in this specification is not strictly perpendicular, but rather allows for an inclination of approximately ±3°.

[0036] In the biological electrode 1, the connector 30 is formed as a snap-on connector. More specifically, the connector 30 is formed as a male connector among snap-on connectors. In this embodiment, the connector 30 includes a first conductive member 40 and a second conductive member 50 that fit together (see FIG. 1 ). Figure 3 ).

[0037] The first conductive component 40 and the second conductive component 50 are formed of, for example, stainless steel. One end of the first conductive component 40 is embedded in the supported portion 21 of the electrode component 20 and extends through the support component 10, while the other end protrudes from the back surface 10b of the support component 10. The second conductive component 50 is arranged on the back surface 10b of the support component 10 in a state of being engaged with the other end of the first conductive component 40. Moreover, by attaching (engaging) a female connector (not shown) of a snap-on connector to the second conductive component 50, the electrode component 20 of the biological electrode 1 is electrically connected to the outside. That is, the connector 30 is configured so that a portion is embedded in the supported portion 21 of the electrode component 20 and extends through the support component 10, and the connection portion with the outside is located on the back surface 10b of the support component 10.

[0038] For example, the electrode member 20 of the biological electrode 1 is electrically connected to the measuring device by attaching (fitting) a female connector attached to the distal end of a lead wire of the measuring device to the second conductive member 50. The measuring device is a device for inputting biological signals detected by the plurality of electrode portions 22 of the electrode member 20 of the biological electrode 1 and processing, displaying, and / or analyzing the input biological signals. The measuring device is not particularly limited, and examples thereof include electroencephalogram measurement devices, wearable information devices, and health monitoring devices.

[0039] Reference Figure 3 The first conductive member 40 and the second conductive member 50 will be described in detail. In the present embodiment, the first conductive member 40 and the second conductive member 50 are formed in a flanged, bottomed cylindrical shape.

[0040] The first conductive component 40 includes a first bottomed cylindrical portion 41 having an open end 41a at one end and a closed end (bottom) 41b at the other end; and a first flange portion 42 extending radially outward from the open end 41a of the first bottomed cylindrical portion 41. The outer diameter of the first bottomed cylindrical portion 41 is set to be approximately the same as the diameter of the through-hole 10c of the support member 10. A radially recessed fitting portion 43 is formed in a portion near the closed end 41b of the outer circumference of the first bottomed cylindrical portion 41. The first flange portion 42 is slightly inclined so that the radial outer side is located closer to the closed end 41b of the first bottomed cylindrical portion 41 than the radial inner side.

[0041] In the first conductive member 40, primarily the surface 42a of the first flange portion 42 opposite the first bottomed cylindrical portion 41 is embedded in the supported portion 21 of the electrode member 20. The first bottomed cylindrical portion 41 is inserted through the through-hole 10c of the support member 10 (i.e., extends through the support member 10). The portion of the first bottomed cylindrical portion 41 on the closed end 41b side (including the fitting portion 43) protrudes from the back surface 10b of the support member 10. Hereinafter, the surface 42a of the first flange portion 42 opposite the first bottomed cylindrical portion 41 is referred to as the "embedded surface."

[0042] The second conductive component 50 includes: a second bottomed cylindrical portion 51 having an open end 51a at one end and a closed end (bottom) 51b at the other end; and a second flange portion 52 extending radially outward from the open end 51a of the second bottomed cylindrical portion 51. The second bottomed cylindrical portion 51 is formed so that the inner diameter increases as it approaches the closed end 51b from the open end 51a. The inner diameter of the open end 51a of the second bottomed cylindrical portion 51 is set to be approximately the same as the outer diameter of the fitting portion 43 formed on the outer peripheral surface of the first bottomed cylindrical portion 41 of the first conductive component 40. In addition, the side surface and the bottom surface of the second bottomed cylindrical portion 51 are connected by a smooth curved surface. The second flange portion 52 has an inclined portion that is inclined in such a way that the outer side is farther away from the closed end 51b of the second bottomed cylindrical portion 51 than the radial inner side.

[0043] The second conductive member 50 is fixed by fitting the open end 51 a of the second bottomed cylindrical portion 51 to the fitting portion 43 of the first bottomed cylindrical portion 41 of the first conductive member 40 by caulking or the like, thereby forming the connector 30 of the biological electrode 1 .

[0044] Here, an example of a method for manufacturing the bioelectrode 1 will be briefly described. In the following description, the connector 30 is pre-attached to the support member 10. Specifically, the first bottomed cylindrical portion 41 of the first conductive member 40 is inserted through the through-hole 10c of the support member 10 from the closed end 41b side, and the open end 51a of the second bottomed cylindrical portion 51 of the second conductive member 50 is fitted into the fitting portion 43 of the first bottomed cylindrical portion 41 of the first conductive member 40, which protrudes from the back surface 10b of the support member 10. This pre-assembles the support member 10 and the connector 30. In other words, in this embodiment, the connector 30 is a component provided on the support member 10 side.

[0045] To manufacture the bioelectrode 1, a liquid or paste-like conductive rubber containing silicone rubber and metal particles is first stirred and then injected into a mold (cavity) shaped like the electrode component 20. The conductive rubber is thereby formed into the shape of the electrode component 20 within the mold.

[0046] Next, the support member 10 (i.e., the assembly of the support member 10 and the connector 30) with the connector 30 attached is placed on the conductive rubber in the mold with its supporting surface 10a facing downward. This places the supporting surface 10a of the support member 10 on a portion of the conductive rubber formed in the shape of the electrode member 20 that corresponds to the supported surface 21a of the supported portion 21. Furthermore, the embedded surface 42a of the first flange portion 42 of the first conductive member 40 is embedded in a portion of the conductive rubber formed in the shape of the electrode member 20 that corresponds to the supported portion 21.

[0047] Next, with the assembly of the support member 10 and the connector 30 placed, the conductive rubber formed into the shape of the electrode member 20 is cross-linked. As a result, the conductive rubber formed into the shape of the electrode member 20 is cured, and the first conductive member 40 is integrated with the electrode member 20. That is, the connector 30 and (the supported portion 21 of) the electrode member 20 are integrally formed. Furthermore, the support member 10, the electrode member 20, and the connector 30 are integrated. Thereafter, the integrated support member 10, the electrode member 20, and the connector 30 are removed from the mold (demolded), and subsequent processing is performed as needed to complete the biological electrode 1.

[0048] As described above, the biological electrode 1 according to the embodiment includes an electrode component 20 made of conductive rubber, which has a plurality of electrode portions 22 that contact the body of a subject. The plurality of electrode portions 22 are formed to protrude from the electrode portion forming surface 21b of the supported portion 21 of the electrode component 20 and are arranged concentrically on the electrode portion forming surface 21b. In addition, the plurality of electrode portions 22 are each formed so that the cross-sectional area gradually decreases from the base portion (root) toward the front end portion, and the cross-sectional center C2 of the front end portion is located radially outward relative to the cross-sectional center C1 of the base portion when viewed from the arrangement center O of the plurality of electrode portions 22.

[0049] Furthermore, in each of the multiple electrode portions 22, the imaginary straight line X connecting the cross-sectional center C1 of the base portion and the cross-sectional center C2 of the front end portion is inclined in such a manner that it moves away from the perpendicular line OL of the electrode portion forming surface 21b passing through the configuration center O as it approaches the front end portion from the base portion.

[0050] Therefore, while ensuring the flexibility and elasticity of each electrode portion 22, the shape of each electrode portion 22 can be made into a shape that is difficult to bend (difficult to fall) in the opposite direction of the expansion direction of each electrode portion 22 (also referred to as the inner side, which refers to the direction toward the arrangement center O of the plurality of electrode portions 22). In other words, compared with the conventional technology, the shape of each electrode portion 22 can be made less susceptible to the load applied to the front end side from the outer tilt direction (see Figure 4 The shape of the electrode 22 is not affected by the dotted arrows in the figure and has a higher rigidity against the load. Therefore, even when a strong pressing force is repeatedly applied to the biological electrode 1, the tip portion of each electrode portion 22 is prevented from bending in the direction opposite to the expansion direction, and the multiple electrode portions 22 can maintain stable contact with the subject's body.

[0051] Furthermore, the plurality of electrode portions 22 are arranged at equal intervals in the circumferential direction. This prevents stress from concentrating on a portion of the electrode portions 22 when a pressing force is applied to the biological electrode 1. Consequently, it is also possible to prevent a portion of the electrode portion 22 from deforming more significantly than the remaining electrode portions 22 and thus losing stable contact with the subject's body.

[0052] Furthermore, in this embodiment, the plurality of electrode portions 22 each have an oblique conical shape with a rounded apex. This effectively prevents the electrode portions 22 from bending in a direction opposite to the expansion direction, and allows the distal end portions of the plurality of electrode portions 22 to stably contact the subject's body without causing discomfort to the subject.

[0053] Furthermore, in this embodiment, in each of the plurality of electrode portions 22, the busbar B1 located farthest from the arrangement center O of the plurality of electrode portions 22 is perpendicular to the electrode portion forming surface 21b (as described above, an inclination of approximately ±3° is permitted). This suppresses the generation of undercuts and prevents degradation of workability during demolding. Furthermore, the shape of each electrode portion 22 can be made less susceptible to loads applied to the distal end from an outwardly inclined direction, thereby increasing rigidity against loads applied from an outwardly inclined direction.

[0054] In addition, in the above-mentioned embodiment, the plurality of electrode portions 22 are arranged concentrically on the electrode portion forming surface 21b. However, this is not limited to this. Figure 5 As shown in FIG, the plurality of electrode portions 22 may also be arranged in a circular shape. In this case, the plurality of electrode portions 22 are arranged so as to be located on the circumference of the imaginary circle 25 on the electrode portion forming surface 21b. Figure 5 In FIG. 1 , symbol O also represents the arrangement center of the plurality of electrode portions 22 (the center of the imaginary circle 25 ), and symbol OL represents a perpendicular line passing through the arrangement center O to the electrode portion forming surface 21 b (the center line of the imaginary circle 25 ).

[0055] Furthermore, in the above-described embodiment, the plurality of electrode portions 22 are arranged so as to be located on the circumferences of two imaginary concentric circles 23 and 24 on the electrode portion forming surface 21b of the supported portion 21 of the electrode member 20. However, the present invention is not limited thereto. The plurality of electrode portions 22 may also be arranged so as to be located on the circumferences of three or more imaginary concentric circles.

[0056] Although not shown in the figure, the biological electrode 1 can include, as necessary, additional electrode portions of any shape that come into contact with the subject's body in addition to the plurality of electrode portions 22 .

[0057] In addition, in the above embodiment, the plurality of electrode portions 22 each have a circular cross section. However, this is not limiting. For example, the plurality of electrode portions 22 may each have a cross section other than a circular shape (eg, a rounded polygon).

[0058] Furthermore, in the above-described embodiment, the plurality of electrode portions 22 each have an oblique conical shape with a rounded vertex, and in each of the plurality of electrode portions 22, the busbar B1 located at the farthest position from the arrangement center O of the plurality of electrode portions 22 is perpendicular to the electrode portion forming surface 21b. However, this is not limiting, and as long as the cross-sectional center C2 of the front end portion is located radially outward from the cross-sectional center C1 of the base portion when viewed from the arrangement center O, it will suffice. For example, Figure 6 As shown, the busbar B1 located at the farthest position from the arrangement center O may be inclined in the same manner as the busbar B2 located at the closest position so as to become further away from the perpendicular line OL of the electrode portion forming surface 21b passing through the arrangement center O as it moves from the base portion toward the tip portion. However, considering the workability during demolding, it is preferable that the plurality of electrode portions 22 each have the shape of the above-described embodiment.

[0059] As mentioned above, although embodiment and its modification of this invention were demonstrated, this invention is not limited to the said embodiment and its modification, It is possible to make further deformation|transformation and change based on the technical idea of ​​this invention.

[0060] Explanation of symbols:

[0061] 1: Biological electrode, 10: Supporting part, 10a: Supporting surface, 10b: Back surface, 10c: Through hole, 20: Electrode part, 21: Supported part, 21a: Supported surface, 21b: Electrode part forming surface, 22: Electrode part, 23, 24: Imaginary concentric circles, 25: Imaginary circle, 30: Connector, 40: First conductive part, 50: Second conductive part, C1: Center of the cross section of the base part of the electrode part, C2: Center of the front end part of the electrode part, O: Configuration center of the plurality of electrode parts, OL: Perpendicular to the electrode part forming surface passing through the configuration center.

Claims

1. A biological electrode comprising: An electrode member made of conductive rubber, the electrode member having a plurality of electrode portions in contact with the subject's body, The plurality of electrode portions are formed protrudingly on the electrode portion forming surface of the electrode component and are arranged in a circular or concentric circle shape on the electrode portion forming surface. The plurality of electrode portions are formed so that their cross-sectional areas gradually decrease from the base portion toward the front end portion, and when viewed from the arrangement center of the plurality of electrode portions, the cross-sectional center of the front end portion is located radially outward of the cross-sectional center of the base portion. In each of the plurality of electrode portions, an imaginary straight line connecting the cross-sectional center of the base portion and the cross-sectional center of the front end portion is inclined so as to be farther away from a perpendicular line of the electrode portion forming surface passing through the arrangement center as it approaches from the base portion to the front end portion. Each of the plurality of electrode portions has an oblique conical shape with a rounded apex. In each of the plurality of electrode portions, a bus bar located farthest from the arrangement center is perpendicular to the electrode portion forming surface.

2. The biological electrode according to claim 1, wherein The plurality of electrode portions are arranged so as to be located on the circumference of a virtual circle or a plurality of virtual concentric circles on the electrode portion forming surface.

3. A biological electrode comprising: Support components; The electrode member made of conductive rubber comprises: a supported portion supported by the supporting member; and a plurality of electrode portions protruding from the supported portion toward a side opposite to the supporting member and in contact with a body of the subject; as well as A connector for electrically connecting the electrode component to the outside, wherein the connector is partially embedded in the supported portion of the electrode component and extends through the supporting component, and a connection portion with the outside is located on the surface of the supporting component opposite to the electrode component. The plurality of electrode portions are arranged in a circular or concentric manner on the electrode portion forming surface of the supported portion, The plurality of electrode portions are formed so that their cross-sectional areas gradually decrease from the base portion toward the front end portion, and when viewed from the arrangement center of the plurality of electrode portions, the cross-sectional center of the front end portion is located radially outward of the cross-sectional center of the base portion. In each of the plurality of electrode portions, an imaginary straight line connecting the cross-sectional center of the base portion and the cross-sectional center of the front end portion is inclined so as to be farther away from a perpendicular line of the electrode portion forming surface passing through the arrangement center as it approaches from the base portion to the front end portion. Each of the plurality of electrode portions has an oblique conical shape with a rounded apex. In each of the plurality of electrode portions, a bus bar located farthest from the arrangement center is perpendicular to the electrode portion forming surface.

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