Support assembly for releasable attachment of a bioelectric electrode

Abstract

An electrode support assembly (1) for releasable attachment of an electrode (2) for bioelectric signal collection comprising a housing (3) and an electrode connector (4) having on a first side (41) an attachment means (42) for releasably attaching the electrode (2) in line with an axial direction (A) of the housing (3), wherein the electrode connector (4) is moveably connected to the housing (3) to allow a movement of the electrode connector (4) in relation to the housing (3) in a lateral direction (L) perpendicular to the axial direction (A) of the housing (3), wherein the electrode support assembly (1) further comprises a bearing (5) allowing lateral movement of the electrode connector (4) and the bearing (5) comprises several balls preferably held in a bearing cage.

Description

[0001] Support assembly for releasable atachment of a bioelectric electrode

[0002] Technical Field

[0003] The invention relates to an electrode support assembly for releasable attachment of a bioelectric electrode for bioelectric signal collection. The electrode support assembly comprises a housing defining an inner space with an opening in an axial direction of the electrode support assembly and an electrode connector accommodated in the housing and having on a first side an attachment means for releasably attaching the electrode.

[0004] Technical Background

[0005] Bioelectrical signals are one of the most basic physiological signals of a human body. Soft and dry electrodes (SDE) - a type of bioelectric electrodes - are increasingly used for collecting bioelectric signals in applications such as electroencephalography (EEG), electrocardiography (ECG) or electromyography (EMG). A common problem of any measurement are so-called artifacts, which is something that may be observed in a scientific investigation or experiment that is not naturally present but occurs as a result of the preparative or investigative procedure. Thus, motion artifacts are all kind of noises or interferences in a recorded signal that come from the electrode movement on a skin of an individual or electrode - skin contact imperfection.

[0006] So-called soft and dry electrodes (SDE) typically comprise an electrode body made from conductive elastomer offering high wear comfort thanks to the softness of the material. At the same time, dry signal acquisition is possible without use of conductive gels, shortening preparation time and further increasing wear comfort. Because soft and dry electrodes adhere directly to the skin, noises cannot be reduced by using conductive gel. Motion artifacts can occur when the person moves or is in motion. In consequence, the (soft and dry) electrode might move relative to the skin of a person and thereby lose proper contact with the skin, which causes a significant deterioration in signal quality, making analysis and interpretation of the signal more difficult and less reliable. The effect can be particularly large when the electrode is attached to a more rigid structure, e.g. a headset. Thus, there is a need to reduce motion artifacts in electrode-based applications.

[0007] WO202326202 and W0202204408 disclose a brain signal sensing headset with an electrode arrangement having a rather large and complex structure. The electrode may pivot in relation to a support structure of the headset so that the electrode makes full contact with the surface of a subject's head. The electrode arrangement does not compensate for lateral or radial movements. Motion artifacts are not reduced.

[0008] EP4014866 discloses an electrode arrangement with a rather large and complex structure. The electrode arrangement comprises an electrode member having several pins, a support shaft member for supporting the electrode member, a frame member for slidably holding the support shaft member in an axial direction thereof, and an elastic member in the form of a spring for biasing the electrode member toward the outside in the axial direction of the support shaft member. The electrode arrangement does not compensate for lateral or radial movements. Motion artifacts are not reduced.

[0009] EP3373802 / WO2017083826 discloses an electrode arrangement where an electrode may pivot in relation to a support structure so that the electrode makes full contact with the surface of a subject's head. The support structure has three arms each provided with an electrode at its end. The support structure may be adjusted relative to a headset to place the electrodes at a desired position and is then locked. The electrode arrangement does not compensate for lateral or radial movements during measurements. Motion artifacts are not reduced.

[0010] US2022273470 describes an electrode assembly for a myoelectric prosthesis allowing at least partial decoupling of the movement of the at least one electrode from the electrode housing case and from the prosthesis socket through the mounting of the at least one electrode using at least one biasing element. The at least partial decoupling of the movement is achieved by a rather complex system requiring one or more resiliently deformable biasing bands.

[0011] Summary of the Invention

[0012] It is an objective of the invention to provide an electrode support assembly and an electrode arrangement for bioelectric signal collection showing reduced motion artefacts. At the same time, the support assembly and the arrangement should have a simple, compact and light design, which does not increase the cost and size of a measurement apparatus unnecessarily.

[0013] At least one of the objectives of the present invention is achieved by an electrode support assembly according to claim 1 and an electrode arrangement according to claim 14.

[0014] The electrode support assembly for releasable attachment of an electrode for bioelectric signal collection comprises a housing and an electrode connector having on a first side an attachment means for releasably attaching the electrode in line with an axial direction of the housing. The electrode connector is moveably connected to the housing to allow a movement of the electrode connector in relation to the housing in a lateral (or radial) direction perpendicular to the axial direction of the housing. The electrode support assembly further comprises a bearing allowing lateral movement of the electrode connector and the bearing comprises several balls preferably held in a bearing cage.

[0015] The presented electrode support assembly reduces lateral motion artifacts originating from relative movement of the electrode in relation to the skin of the person in a direction approximately parallel to the skin surface. By allowing a degree of freedom within the electrode support assembly in lateral X,Y-direction (perpendicular to the axial direction A), i.e. along the skin surface, relative movement can be compensated in that only the housing moves and the electrode remains at the predefined position. The working principle may be based on a bearing surface, e.g. a flat backside of e.g. a female snap-on connection for the electrode, sliding on a bearing, e.g. balls secured in ball bearing cage, accommodated within the housing. A rotation around the axial direction may be also possible.

[0016] Further embodiments of the invention are set forth in the dependent claims.

[0017] In some embodiments the housing may define an inner space with an opening in an axial direction of the electrode support assembly, and the electrode connector may be accommodated in the housing in a laterally moveable manner.

[0018] In some embodiments the electrode support assembly may further comprise a bearing allowing or facilitating lateral movement of the electrode connector and accommodated and retained within the inner space of the housing. The electrode connector may have on a second side opposite the first side a bearing surface bearing against the bearing, wherein the inner space and the opening of the housing are dimensioned such that the electrode connector is moveable within the inner space in lateral direction.

[0019] Thus, in an embodiment of the invention, the electrode support assembly for releasable attachment of an electrode for bioelectric signal collection comprises a housing defining an inner space with an opening in an axial direction of the electrode support assembly, and an electrode connector accommodated in the housing and having on a first side an attachment means for releasably attaching the electrode. The electrode support assembly further comprises a bearing accommodated and retained within the inner space of the housing. The electrode connector has on a second side opposite the first side a bearing surface bearing against the bearing. The inner space and the opening of the housing are dimensioned such that the electrode connector is moveable within the inner space in a lateral direction, i.e. perpendicular to the axial direction of the electrode support assembly. The inner space and the opening of the housing may be dimensioned such that a relative lateral movement of the electrode connector and ultimately the electrode in relation to the housing is at least 1 mm, preferably at least 2 mm, more preferably at least 5 mm, from a central position.

[0020] In some embodiments the bearing may comprise several balls held in a ball bearing cage. The ball bearing cage may be a circular ball bearing cage having an axial, central opening allowing for electrically contacting the electrode, e.g. via a wire.

[0021] In some embodiments the electrode connector has a disc-shaped bearing plate forming the bearing surface on the second side and comprising the attachment means on the opposite first side. The diameter of the bearing plate may be smaller than the diameter of the inner space and lager than the diameter of the opening.

[0022] In some embodiments the opening of the housing may have a smaller diameter than the inner space of the housing and the bearing surface of the electrode connector may have a larger diameter than the opening. Thereby the electrode connector may be retained in the housing without any additional locking means. The diameter of the opening and the inner space also limits the relative moving range of the electrode connector and finally the electrode attached to the electrode connector with respect to the housing.

[0023] In some embodiments the housing may comprise a housing body forming the inner space and a housing lid forming the opening. The housing or the housing body may be a separate part attached to a support device, e.g. a headset, or may be an integral part of the support device. The lid may be screwed or otherwise attached to the housing body.

[0024] In some embodiments the electrode connector may be at least partially accommodated and retained within the inner space of the housing. Such retainment may be achieved by the respective dimensions of the inner space, the opening, and the electrode connector itself.

[0025] In some embodiments the attachment means of the electrode connector may be accessible by the electrode through the opening of the housing. The attachment means may be arranged in the inner space of the housing or may be arranged within or extending through the opening of the housing. When the attachment means are within or extending through the opening it has a smaller diameter than the opening to allow lateral movement of the electrode connector.

[0026] In some embodiments the housing may comprise a through hole opposite the opening and / or the electrical connector may comprise a through hole on the second side, said through holes being suitable for electrically connecting the electrode with a measurement device. In some embodiments the inner space may be designed such that the electrode connector has clearance in axial direction. The clearance may be in a range of 0.5-3 mm.

[0027] The bearing abuts against an inner wall of the inner space opposite the opening. In some embodiments, the inner wall may be provided with a recess, which may act as a raceway, for accommodating the bearing e.g. in form of a ball bearing to prevent lateral movement of the ball bearing cage. A clearance in axial direction of the electrode in the inner space should not be too large in order to prevent the ball bearing falling out of the recess.

[0028] In some embodiments the attachment means of the electrode connector may be a part of a snap-on or snap-fit connector preferably in the form of a snap fastener or snap button, for attachment of a corresponding attachment means of the electrode.

[0029] In some embodiments the housing and the electrode connector are made of non-conductive material, preferably plastic material.

[0030] The invention further refers to an electrode arrangement for bioelectric signal collection comprising the electrode support assembly as described above and a bioelectric electrode, preferably a soft and dry electrode.

[0031] In some embodiments the electrode may comprise a conductive electrode body having attachment means on a connector side for attaching the electrode to the electrode connector of the electrode support assembly.

[0032] In some embodiments the electrode may comprise a contact side opposite the connector side for contacting a region of interest of a person.

[0033] In some embodiments the contact side of the electrode may be provided with several flexible pins.

[0034] When the electrode arrangement is in use, an electrode, preferably a soft and dry electrode, is releasably attached to the electrode support assembly via the attachment means of the electrode connector. The electrode arrangement e.g. as part of a headset is then placed on a person of interest. Thereby the electrode contacts a region of interest of the person by applying a force onto the electrode towards the person. When the person moves, the headset may also move relative to the region of interest of the person. Due to the degree of freedom of the electrode connector in lateral direction, the electrode may remain at the same location without the risk of losing proper contact with the person's skin. Motion artefacts are reduced, and signal quality is significantly improved. Brief Explanation of the Figures

[0035] The invention is described in greater detail below with reference to embodiments that are illustrated in the figures. The figures show:

[0036] Fig. 1 a perspective view of an electrode support assembly onto a first side;

[0037] Fig. 2 a perspective view of the electrode support assembly of Fig. 1 onto an opposite second side;

[0038] Fig. 3 a cross-section of the electrode support assembly of Fig. 1 with an electrode;

[0039] Fig. 4 an exploded view of the electrode support assembly of Fig. 1 with an electrode from the first side;

[0040] Fig. 5 an exploded view of the electrode support assembly of Fig. 1 with an electrode from the second side;

[0041] Fig. 6 raw data measurement taken from an active forearm of a person with (a) or without (b) an electrode support assembly;

[0042] Fig. 7 raw data measurement taken from an inactive forearm of a person with (a) or without (b) an electrode support assembly.

[0043] Embodiments of the Invention

[0044] Figs. 1 and 2 show perspective views of an electrode support assembly 1 for releasable attachment of an electrode for bioelectric signal collection. Figs. 3 to 5 show the electrode support assembly 1 of Figs. 1 or 2 including a soft and dry electrode 2 in different views.

[0045] The electrode support assembly 1 comprises a housing 3, which is in the shown embodiment formed by a housing body 33 and a housing lid 34. The housing 3 may be a separate part attached to a further structure of a measurement device for measuring bioelectric signals. The housing or the housing body may also be an integral part of a support structure of a measurement device, e.g. a headset. The housing body 33 and the housing lid 34 may be attached to each other e.g. by means of screws 6.

[0046] The housing 3 forms an inner space 31 with an opening 32 along an axial direction A of the electrode support assembly 1 . The inner space 31 may thereby be formed by the housing body 33 and the opening 32 may be formed by the housing lid 34. Opposite the opening, the housing 3 or the housing body 33 is provided with a through hole 35 for electrically connecting the electrode via a wire. The electrode support assembly 1 further comprises an electrode connector 4 and a bearing 5, both accommodated and retained within the inner space 31 of the housing 3. The bearing 5 allows lateral movement (direction L) of the electrode connector 4 in relation to the housing

[0047] 3 and may be a ball bearing with a circular ball cage provided with a central through opening. The bearing 5 abuts against an inner wall of the inner space 31 opposite the opening 32. The inner wall may be provided with a recess 36 for accommodating the bearing 5 to prevent lateral movement of the bearing 5.

[0048] The electrode connector 4 in the shown embodiment comprises a bearing plate 45 having a first side 41 and a second side 43 opposite the first side 41. The electrode connector 4 further comprises an attachment means 42 - in the shown embodiment in the form of a snap-connector - which is arranged centrally on the first side 41 of the bearing plate 45. The second side 43 of the bearing plate 45 forms a bearing surface 44, which in use of the electrode support assembly abuts against the bearing 5. Due to the bearing 5, the electrode connector 4 can freely rotate around the axial direction A.

[0049] The inner space 31 and the opening 32 of the housing 3 are dimensioned such that the electrode connector 4 with an attached electrode 5 can freely move in lateral direction L. Thereby the electrode 2 remains at a region of interest of the person's skin even when the person moves. Relative movements of the housing 3 with respect to the person's skin can be compensated. The possible lateral movement is preferably at least 2mm, more preferably at least 5 mm, from the centre of the opening 32. At the same time the inner space 31 may be dimensioned that the bearing plate 45 has some play or clearance in axial direction within the inner space 31 , preferably about 1-3 mm.

[0050] The electrode 2 in the shown embodiment is a soft and dry electrode 2 with a conductive electrode body 21 of elastomeric material having an attachment means 22 on a connector side of the electrode 2 and several flexible pins 23 on an opposite contact side of the electrode 2. The attachment means 22, 42 of the electrode 2 and the electrode connector

[0051] 4 are part of a snap-on or snap-fit connector preferably in the form of a snap fastener or snap button.

[0052] For electrically connecting the electrode 2 with a measuring device, the housing 3 and the electrode connector 4 are each provided with a through hole 35, 46 for applying an electric wire connection. The through holes 35, 46 are arranged centrally along the axial direction A of the electrode support assembly 1. The bearing 5 has a central opening to provide enough space for a wire even upon lateral movement of the electrode connector 4 in relation to the housing 3. Fig. 6 and Fig. 7 show comparative raw data measurements of a bioelectric signal (amplitude in pV) over time (in seconds) recorded from an active (Fig. 6) or inactive (Fig. 7) forearm of a person. In the case of the active forearm, the hand was repeatedly closed to a fist and opened again.

[0053] The comparative measurements were in each case taken in parallel with the above described electrode support assembly (Fig. 6(a) or Fig. 7(a)) and without the above described electrode support assembly (Fig. 6(b) or Fig. 7(b)). Therefore, an electrode using the above electrode support assembly and an electrode without such electrode support assembly, i.e. a standard connector, were both fixed to a rigid element to experience the same condition on the forearm. A reference electrode was placed approx. 5 cm apart from both measurement electrodes.

[0054] Fig. 6 shows the comparative measurements of an active forearm during repeated opening and closing of the hand. Fig. 7 shows the comparative measurements of an inactive, resting forearm, i.e. without repeated opening I closing of the hand.

[0055] In both cases, motion artefacts could be considerably reduced by using the above described electrode support assembly.

[0056] Reference Signs

[0057] 1 electrode support assembly

[0058] 2 bioelectric electrode

[0059] 21 electrode body

[0060] 22 attachment means

[0061] 23 flexible pin

[0062] 3 housing

[0063] 31 inner space

[0064] 32 opening

[0065] 33 housing body

[0066] 34 housing lid

[0067] 35 through hole

[0068] 36 recess 4 electrode connector

[0069] 41 first side

[0070] 42 attachment means

[0071] 43 second side 44 bearing surface

[0072] 45 bearing plate

[0073] 46 through hole

[0074] 5 bearing (ball bearing)

[0075] 6 screw A axial direction

[0076] L lateral direction

Claims

Claims1. Electrode support assembly (1) for releasable attachment of an electrode (2) for bioelectric signal collection comprising a housing (3) and an electrode connector (4) having on a first side (41) an attachment means (42) for releasably attaching the electrode (2) in line with an axial direction (A) of the housing (3), characterized in that the electrode connector (4) is moveably connected to the housing (3) to allow a movement of the electrode connector (4) in relation to the housing (3) in a lateral direction (L) perpendicular to the axial direction (A) of the housing (3), wherein the electrode support assembly (1) further comprises a bearing (5) allowing lateral movement of the electrode connector (4) and the bearing (5) comprises several balls preferably held in a bearing cage.

2. Electrode support assembly (1) according to claim 1 , wherein the housing (3) defines an inner space (31) with an opening (32) in an axial direction (A) of the electrode support assembly (1), and wherein the electrode connector (4) is accommodated in the housing (3).

3. Electrode support assembly according to claim 2, wherein the bearing (5) is accommodated and retained within the inner space (31) of the housing (3), and in that the electrode connector (4) has on a second side (43) opposite the first side (41) a bearing surface (44) bearing against the bearing (5); wherein the inner space (31) and the opening (32) of the housing (3) are dimensioned such that the electrode connector (4) is moveable within the inner space (31) in lateral direction (L).

4. Electrode support assembly according to claim 3, wherein the bearing cage is a circular ball bearing cage preferably having an axial, central opening allowing for electrically contacting the electrode.

5. Electrode support assembly according to one of the claims 3 or 4, wherein the electrode connector (4) has a disc-shaped bearing plate (45) forming the bearing surface (44) on the second side (43) and comprising the attachment means (42) on the opposite first side (41).

6. Electrode support assembly according to one of claims 2 to 5, wherein the opening (32) of the housing (3) has a smaller diameter than the inner space (31 ) of the housing (3) and the bearing surface (44) of the electrode connector (4) has a larger diameter than the opening (32).

7. Electrode support assembly according to one of to one of claims 2 to 6, wherein the housing (3) comprises a housing body (33) forming the inner space (31) and a housing lid (34) forming the opening (32).

8. Electrode support assembly according to one of claims 2 to 7, wherein the electrode connector (4) is at least partially accommodated and retained within the inner space (31) of the housing (3).

9. Electrode support assembly according to one of claims 2 to 8, wherein the attachment means (42) of the electrode connector (4) is accessible through the opening (32) of the housing (3).

10. Electrode support assembly according to one of claims 2 to 9, wherein the attachment means (42) of the electrode connector (4) is arranged within or extends through the opening (32) of the housing (3).

11. Electrode support assembly according to one of claims 2 to 10, wherein the housing (3) comprises a through hole (35) opposite the opening (32) and / or the electrical connector (4) comprises a through hole (46) on the second side (43), said through holes (35, 46) being suitable for electrically connecting the electrode (2) with a measurement device.

12. Electrode support assembly according to one of claims 2 to 11 , wherein the inner space (31) is designed such that the electrode connector (4) has clearance in axial direction (A).

13. Electrode support assembly according to one of the preceding claims, wherein the attachment means (42) of the electrode connector (4) is a part of a snap-on or snap- fit connector preferably in the form of a snap fastener or snap button, for attachment of a corresponding attachment means of the electrode (2).

14. Electrode arrangement comprising the electrode support assembly (1) of one of the preceding claims and a bioelectric electrode (2), preferably a soft and dry electrode.

15. Electrode arrangement according to claim 14, wherein the electrode (2) comprises a conductive electrode body (21) having attachment means (22) on a connector side for attaching the electrode (2) to the electrode connector (4) of the electrode support assembly (1).

16. Electrode arrangement according to one of claims 14 to 15, wherein the electrode (2) comprises a contact side opposite the connector side for contacting a region of interest of a person.

17. Electrode arrangement according to one of claims 15 to 16, wherein the contact side of the electrode (2) is provided with several flexible pins (23).

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