ELECTRODE FOR APPLICATION TO HUMAN SKIN

Abstract

An electrode for application to the human skin, includes an electrically non-conductive support which on its upper side, facing away from the skin, has a protruding, electrically conductive connecting element with a terminal for removable connection of a signal conductor. A transverse conductor is provided which extends at least partially on the opposite, lower side of the support and is electrically coupled to the connecting element and to a contact medium facing the skin. The connecting element is made of a single piece, which on the one hand is connected to the transverse electrical conductor, and on the other hand has the terminal for releasable connection of a separate signal conductor.

Claims

1. An electrode for application to the human skin comprising an electrically non-conductive carrier having on its top side remote from the skin a projecting, electrically conductive connecting element with a connection location for releasably connecting a signal conductor, wherein there is provided a transverse conductor extending at least partially on the opposite underside of the carrier, being electrically connected to the connecting element and a contact medium facing the skin, characterised in that the connecting element comprises a single part which on the one hand is in connected relationship with the electrical transverse conductor and on the other hand has the connection location for releasably connecting a separate signal conductor.

2. The electrode according to claim 1, wherein the connecting element comprises metal, preferably a deep-drawn metal sheet, or conductive plastic, preferably doped with conductive carbon fibres ABS.

3. The electrode according to claim 1, wherein the connecting element has a substantially spherical head, an adjoining reduced-diameter neck and a flange-shaped laterally projecting holding region at the end of the neck remote from the head.

4. The electrode according to claim 3, wherein the laterally projecting flange-like holding region is plate-shaped.

5. The electrode according to claim 1, wherein the connecting element is overall of a substantially rotationally symmetrical configuration.

6. The electrode according to claim 1, wherein the connecting element on the one hand and the contact medium on the other hand are arranged at laterally mutually displaced locations (distance d) on the carrier.

7. The electrode according to claim 1, wherein the contact mediumpreferably arranged in a recess of a plaster layeris a gel preferably doped with chlorides, is in the form of a conductive adhesive or a saline-filled sponge.

8. The electrode according to claim 1, wherein the connecting elementpreferably with a reduced-diameter neckprojects through an opening in the carrier.

9. The electrode according to claim 8, wherein the connecting elementapart from possible lateral contact in the region of the openingis connected to the carrier only on the underside of the carrier, that is towards the skinpreferably with the interposition of a flat transverse conductor.

10. The electrode according to claim 1, wherein the connecting element has a laterally projecting holding region which is arranged between a support layer and the carrier, wherein the support layer extends laterally beyond the holding region of the connecting element and is there firmly connected to the carrierpreferably glued.

11. The electrode according to claim 10, wherein the support layer is in the form of a double-sided adhesive tape or a tape made of a thermally activatable adhesive or a tape made of a thermoplastic material suitable for direct thermoplastic connection to the carrier, which is glued on the one side with the connecting element and the carrier.

12. The electrode according to claim 11, wherein the double-sided adhesive tape is glued on the other side with a plaster layer, wherein the plaster layerpreferably by means of a patient-side coating made of biocompatible adhesivecan be glued on the skin to fix the electrode.

13. The electrode according to claim 10, wherein the support layer is formed by a plaster layer, wherein the plaster layerpreferably by means of a patient-side coating made of biocompatible adhesivecan be glued on the skin to fix the electrode.

14. The electrode according to claim 13, wherein the plaster layer is glued to the carrier and the holding region of the connecting element by means of a layer applied thereto of self-adhesive or a thermally activatable adhesive.

15. The electrode according to claim 1, wherein the carrier material comprises a dimensionally stable film, in particular of PET.

16. The electrode according to claim 1, wherein the carrier material is coated on the side facing the skin with adhesive which is preferably self-adhesive or thermally activatable.

17. The electrode according to the classifying portion of claim 1, wherein the transverse conductor comprises at least two different electrically conductive materials, one of which is galvanically connected to the connecting element and another is galvanically connected to the contact medium.

18. The electrode according to claim 17, wherein the transverse conductor is in the form of a preferably strip-shaped layer of a first electrically conductive material which in the region of the contact mediumand preferably only thereis provided, preferably coated, with a second electrically conductive material.

19. The electrode according to claim 18, wherein the first electrically conductive material is a metal or a metal alloy, a plastic film which is conductive throughout or superficially, for example by conductive carbon fibres, or a textile material which is conductive throughout or superficially.

20. The electrode according to claim 18, wherein the second material is formed by a pair of silver/silver chloride or tin/tin chloride or another redox pair suitable for depolarising the electrode.

21. The electrode according to claim 1, wherein the connecting element in a holding region in which it is connected, preferably glued, to the rest of the electrode, has at least one recess and/or a bore in its surface.

22. The electrode according to claim 4, wherein the bores pass through the plate-shaped holding region.

23. The electrode according to claim 4, wherein the recesses at the peripheral edge of the plate-shaped holding region are tooth-shaped and/or wave-shaped.

24. The electrode according to claim 1, wherein the carrier and a support layer connected thereto has at least one incision in the region beside the connecting element, which incision allows mobility of the connecting element with respect to a plaster layer provided for gluing to the skin.

25. The electrode according to claim 1, wherein an electrically conductive adhesive is provided between the transverse conductor and the connecting element or a flange projecting laterally therefrom.

26. The electrode according to claim 1, wherein the connecting element is pre-mounted on the electrode and permanently connected thereto.

27. A method of producing an electrode for application to the human skin, in particular according to claim 1, the method comprising: applying, preferably by thermally activated gluing, a strip-shaped transverse conductor to the underside facing the skin of an electrically non-conductive carrier, producing, preferably by punching, a through opening through the transverse conductor and the carrier, introducing a one-piece connecting element from the underside of the carrier into the opening, such that a connection location for a signal conductor projects on the opposite top side of the carrier and the connecting element bears with a laterally projectingpreferably plate-shaped holding region against the transverse conductor, and covering the holding region of the connecting element with a support layer which is glued to the carrier laterally beside the holding region.

28. The method according to claim 27, further comprising: applyingpreferably gluinga plaster layer which is adhesive on the skin side to the carrier and/or the support layer, and introducing an electrical contact mediumpreferably a gelinto a recess in the plaster layer such that the subjacent transverse conductor is contacted.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0016] Further advantages and details of the invention are described more fully with reference to the following description of the drawings, in which:

[0017] FIG. 1 is in a diagrammatic view from below (later the side towards the skin) the production steps of an embodiment of an electrode according to the invention to the finished electrode,

[0018] FIG. 2 is a corresponding plan view, wherein only a part of the method steps is shown in a plan view,

[0019] FIG. 3 shows the sequence of sections along the line A-A of FIG. 1, wherein the representation is to be interpreted for better visualization as a diagrammatic illustration. In reality the layer sequence can be of different dimensioning, as is usual with medical electrodes,

[0020] FIGS. 4, 5 and 6 show substantially the same illustrations as in FIGS. 1, 2 and 3, but for another embodiment, and

[0021] FIGS. 7 and 8 are views from below of embodiments of an electrical connecting element.

DETAILED DESCRIPTION OF THE INVENTION

[0022] The basic starting point is an electrically non-conductive carrier 1. The carrier material serves to anchor the electrical components of the electrode. It may for example comprise a (flexible) film (for example, PET or TPU), which is coated on the underside facing upwardly in the drawing of FIG. 1 with an adhesive 2 which, for example, can be self-adhesive (pressure sensitive adhesive) or thermally activatable (hot melt).

[0023] A strip-shaped transverse conductor 3 is now attached, in particular glued, to the carrier material, in a next step. According to a preferred variant of the invention the transverse conductor has two differently electrically conductive materials, one of which is later galvanically connected to the electrical connecting element and while the other is galvanically connected to the contact medium (gel).

[0024] The illustrated embodiment is a strip-shaped conductor shown in black, made of a plastic doped with conductive carbon fibres. In the region of the later contact location with the electrical contact medium (gel) the transverse conductor 3 (first material) is coated with a second electrically conductive material, for example, a layer 3a of silver/silver chloride or tin/tin chloride or another redox pair.

[0025] Preferably that layer 3a provided for the appropriate electrical properties from the contact location to the later gel is only provided where the gel is later provided. Otherwise a normal conductor 3, which is considerably less expensive, is sufficient to produce the electrical connection to the electrical connecting element described below.

[0026] In a further step a bore 4 is now provided through the electrical transverse conductor 3 and the carrier 1. This can be done for example by punching. There then follows the introduction of the electrically conductive connecting element 5 which has a substantially spherical-head-shaped connection location 5a for releasably connecting a commercially usual signal conductor (not shown) and which projects beyond the top side 1a of the carrier 1.

[0027] In the illustrated embodiment, adjoining the substantially spherical head 5a the electrical connecting element has a reduced-diameter neck 5b on which finally a flange-like laterally projecting holding region 5c is disposed at the end facing away from the head 5a.

[0028] Overall, the laterally projecting flange-shaped holding region 5c has a substantially plate-shaped configuration. On the one hand, it serves for making electrical contact with the transverse conductor 3, by being clamped between the carrier 1 and the plate-shaped flange 5c. On the other hand, the plate-shaped flange serves for producing the mechanical hold of the electrical connecting element, in particular against tensile loads which can be exerted by a signal cable on the head 5a and thus the entire connecting element 5.

[0029] Preferably, an electrically conductive adhesive is provided between the transverse conductor 3 and the connecting element 5 or a flange 5c projecting laterally therefrom.

[0030] In contrast to the hitherto usual riveted two-piece connecting elements comprising the upwardly projecting stud (top knob) and the subjacent eyelet (lower knob), according to the invention a connecting element 5 is used, which comprises a single part, which is connected on the one hand to the electrical transverse conductor 3 and on the other hand has the connection location 5a for releasably connecting a signal conductor (not shown here). This permits cost-effective production of the electrode because the mostly expensive eyelet (lower knob) can be omitted. The one-part design of the connecting element is sufficient for the mechanical anchoring effect.

[0031] The demands in terms of the electrical properties are low. This means simple structures, for example a deep-drawn metal part, can be used as a connecting element 5. The somewhat more difficult electrical functions are therefore not performed here by the otherwise usual eyelet (lower knob) but that end of the transverse conductor 3, which is in communication with the subsequently applied electrical contact medium (gel). This therefore involves a separation of tasks. Apart from the basic property of being electrically conductive the electrical connecting element is substantially responsible for the mechanical hold in the electrode while the transverse conductor is largely free of mechanical tasks. This makes it possible to make a favourable choice of material. In particular, it is possible to provide more expensive materialswhich are favorable from an electrical point of viewonly (location 3a) where contact with the gel later takes place.

[0032] The electrically conductive connecting element can comprise a deep-drawn metal sheet, as already mentioned. It is then at least partially hollow inside. It may, however, also consist of a conductive plastic, for example, ABS, which is doped with conductive carbon fibres.

[0033] Desirably, the connecting element will be substantially rotationally symmetrical. Other variants are also possible.

[0034] In order to fix the electrical connecting element 5c definitively in the electrode and in particular to secure it against pressure loads on the head 5a a support layer 6 is applied in a next step. The support layer 6 may for example comprise a double-sided adhesive tape which is glued on the underside in FIG. 1 to the connecting element 5 (specifically to the plate-shaped holding region 5c) and to regions of the underside 1a of the carrier 1.

[0035] In that case, pressure can be exerted on the layers so that they are correspondingly contoured and connect with each other. However the cross section shown in FIG. 3 after attaching the support layer 6 with the edges shown there is only to be seen as a diagrammatic representation. In actual fact the layer thicknesses are usually smaller and the layouts of the layers are substantially more rounded.

[0036] The double-sided adhesive tape 6 which is glued to the carrier 1, the electrical transverse conductor 3, and the holding region 5c of the electrical connecting element 5 on the one side, is now glued on the other side with a plaster layer 7, and the plaster layer can be glued to the skin, preferably by means of a patient-side coating made of biocompatible adhesive to fix the electrode.

[0037] Contrary to the illustrated embodiments, the support layer can also be formed directly from the plaster layer (without interposed double-sided adhesive tape). In that case, it is also possible to glue the plaster layer to the carrier 1 and the holding region 5c of the connecting element 5 by way of a layer of self-adhesive applied to it or a thermally activatable adhesive.

[0038] Reference will now be made back to the embodiment of FIGS. 1 to 3. The plaster material 7 shown there is firmly connected to the carrier 1 not only by way of the double-sided adhesive tape 6, but also the adhesive on the underside 2 of the carrier 1.

[0039] The plaster material finally serves to fix the electrode on the patient's skin. Suitable plaster materials may for example comprise a film (for example PE), a foam tape (for example PE foam) or non-woven materials. The plaster materials are usually coated on the patient side with a biocompatible adhesive 7a.

[0040] A final production step of the electrode shown in FIGS. 1 to 3 involves the introduction of the electrical contact medium into a recess 7b provided in the plaster material 7 for that purpose. The electrical contact medium allows the (preferably ion-based) conduction of body-generated electrical potentials or device-generated measurement or stimulation currents from the body surface (skin) to the electrical contact element and vice versa. The contact medium may comprise for example a chloride-doped gel which is present either in more or less liquid form (more or less gelled) or as a crosslinked polymer matrix (hydrogel). However, it is also possible to produce the electrical contact medium by other means, for example as a conductive adhesive or as a saline-filled sponge.

[0041] At any event, the electrical contact medium 8, as is shown by the last step in FIGS. 1 to 3, is introduced into the recess 7b. It contacts therein the end region 3a (there is the second material of the transverse conductor, in particular silver/silver chloride).

[0042] The co-operation of the specially-designed end region of the transverse conductor 3, in particular the coating with silver/silver chloride or another suitable material on the one hand and the material of the electrically conductive contact medium 8 on the other hand, makes it possible to achieve favorable electrical properties of the electrode, for example noise-free signal transmission or depolarizing effects. The use of the relatively expensive second material 3a at the end of the transverse conductor 3 can remain restricted to that region in which contact with the contact medium 8 takes place. This further reduces the costs.

[0043] Overall, the production as shown in FIGS. 1 to 3 gives a decentralized electrode, in which the connecting element 5 on the one hand and the contact medium 8 (gel) on the other hand are arranged on the carrier 1 at laterally mutually displaced locations (distance d).

[0044] The method steps essential for the embodiment shown in FIGS. 1 to 3 are the following:

[0045] applying, preferably by thermally activated gluing, a strip-shaped transverse conductor to the underside facing the skin of an electrically non-conductive carrier,

[0046] producing, preferably by punching, a through opening through the transverse conductor and the carrier,

[0047] introducing a one-piece connecting element from the underside of the carrier into the opening, such that a connection location for a signal conductor projects on the opposite top side of the carrier and the connecting element bears with a laterally projectingpreferably plate-shaped holding region against the transverse conductor, and

[0048] covering the holding region of the connecting element with a support layer which is glued to the carrier laterally beside the holding region.

[0049] Finally, the following steps are then also effected to complete the electrode:

[0050] applying, preferably gluing, a plaster layer which is adhesive on the skin side to the carrier and/or the support layer, and

[0051] introducing an electrical contact mediumpreferably a gelinto a recess of the plaster layer such that the subjacent transverse conductor is contacted.

[0052] In the embodiment illustrated in FIGS. 4 to 6, most of the method steps are the same as those in FIGS. 1 to 3, for which reason the same reference numerals denote the same parts.

[0053] The difference is essentially in step 5. Specifically as shown in FIG. 4 two incisions 9 are made through the entire composite. In the next step 6 the plaster material 7 is then glued only in the upper region and at the bottom to the wings (for example, by local thermal activation), but not in the region of the flap which thereby remains movable.

[0054] Overall the embodiment shown in FIGS. 4 to 6 involves a movable flap 10 which carries the connecting element 5 with the connection location 5a. The movable flap can compensate for tensile loads on the signal conductor (not shown) and thus on the connection location 5a, so that same is not transmitted fully to the electrode. Overall this improves the adhesion of the electrode to the skin of the patient.

[0055] FIG. 7 shows an embodiment by way of example of a holding region 5c which projects laterally from the connecting element 5 in the form of a flange. This holding region or flange has bores 5d. When gluing the electrode adhesive penetrates into those bores and thus improves the adhesion and resistance to rotation of the connecting element with the parts of the rest of the electrode.

[0056] The embodiment shown in FIG. 8 serves for the same purpose. Here indentations 5e are provided at the peripheral edge of the plate-shaped holding region. The hot melt adhesive also penetrates thereinto and thus improves adhesion.

[0057] The signal conductor (not shown) has a known configuration and usually comprises an insulated flexible cable which leads from an evaluation device or power supply to the electrode. The signal conductor itself is not part of the electrode, that is to say it is formed separately from same and its connecting element. At its electrode end, the signal conductor usually carries a coupling portion, by way of which it is mechanically and electrically releasably connectable to the connection location of the connecting element of the electrode, which in turn is preferably pre-mounted on the electrode and permanently connected thereto.