Electrode with protected edge area

Abstract

Medical electrode comprising a base body (101) on which an electrically conductive first layer (102) and a cover layer (103) are arranged, the cover layer comprising an overhang (107) which partially covers the first layer (102), and an electrically conductive second layer (105) which is arranged on the first layer (102), the second layer (105) comprising an electrically conductive polymer selected from the group consisting of a polyacetylene, a polyvinyl alcohol, a polyfluorene, a polyphenylene, a polyphenylene vinylene, a polypyrene, a polyazulene, a polynaphthalene, a polypyrrole, a polycarbazole, a polyindole, a polyazepine, a polyaniline, a polyacene, a polythiophene, a polythiophene vinylene, a poly-p-phenylene sulfide, a polypyridine or functionalized derivatives, precursors or mixtures thereof;wherein the top layer (103) further comprises a recess (108), wherein the second layer (105) is arranged exclusively within the recess (108), and wherein the outwardly facing surface of the second layer (105) is spaced apart from the outwardly facing surface of the top layer (103), leaving a free area within the recess (108).

Description

AREA OF INVENTION

[0001] The present invention relates to the field of medical technology, in particular medical electrodes which can be used, for example, for electrical stimulation, detection or ablation in or on the human body. TECHNICAL BACKGROUND

[0002] Medical electrodes are subject to stringent requirements. The conductive elements of an electrode are often coated with a soft layer, which is exposed to mechanical stress during normal use and can therefore be damaged or even worn away. Particularly for medical electrodes with a flexible base, good protection against damage is desirable. Examples of medical electrodes and their manufacture are disclosed in US 2019 / 0290898A1 and EP 3284509A1. US 6915159B1 describes an electrode structure for an iontophoresis device and a method for its fabrication.The electrode structure for the iontophoresis device comprises a base with a substrate film, a molded part, an anode-side and a cathode-side electrode layer designed to extend from the inner base of the molded part through the outer circumferential section, and an insulating layer formed in the outer circumferential section of the molded part. The molded part of the base has a recessed area in which an anode-side and a cathode-side conductive layer are separately integrated. A cover element is incorporated to seal between these conductive layers and the insulating layer. An adhesive film for skin attachment is applied to the back of the carrier film, and a protective film for the adhesive film is provided on the cover element. PREFERRED EXECUTION FORMS

[0003] The object of the present invention is to solve one or more of the problems described above and further problems of the prior art. For example, the invention enables the production of particularly stable medical electrodes that are well protected against damage. Furthermore, the present invention provides electrodes with improved stability, performance, handling, and / or measurement sensitivity.

[0004] These tasks are solved by the methods and devices described herein, in particular those described in the patent claims.

[0005] Preferred embodiments of the invention are described in the attached patent claims.

[0006] The following embodiments serve for general illustration: 1. Medical electrode comprising a base body on which an electrically conductive first layer and a cover layer are arranged, wherein the cover layer includes an overhang which partially covers the first layer. 2. Medical electrode according to embodiment 1, wherein the cover layer comprises a depression. 3. Medical electrode according to embodiment 2, wherein the depression tapers or widens towards the base body. 4. Medical electrode according to one of the preceding embodiments, wherein the overhang comprises a side wall which is arranged at an angle (A) to the surface of the first layer which is (i) less than 80° or (ii) 110° to 170°. 5. Medical electrode according to one of the preceding embodiments, further comprising an electrically conductive second layer arranged on the first layer. 6. Medical electrode according to embodiment 5, wherein the second layer comprises an electrically conductive polymer. 7. Medical electrode according to embodiment 6, comprising the electrically conductive polymer PEDOT. 8. Medical electrode according to one of the preceding embodiments 5 to 7, wherein the second layer is arranged exclusively within the recess, wherein the outwardly facing surface of the second layer is spaced apart from the outwardly facing surface of the cover layer. 9. Medical electrode according to one of the preceding embodiments, wherein the base body comprises a flexible polymer substrate. 10. Medical electrode according to one of the preceding embodiments, further comprising a conductor track which is electrically conductively connected to the first layer. 11. Medical electrode according to one of the preceding embodiments, wherein the overhang is arranged and configured to mechanically stabilize the first layer. 12. Medical electrode according to one of the preceding embodiments, wherein the overhang is arranged and configured to enable an electrical charge exchange between a liquid external medium and the first or, if applicable, second layer from different directions. 13. Medical electrode according to one of the preceding embodiments, wherein the overhang is arranged and configured to protect the base body from the ingress of liquid. 14. Medical electrode according to one of the preceding embodiments, wherein the edge of the first layer is substantially completely covered by the top layer. 15. Use of a medical electrode according to one of the preceding embodiments in a device designed for electrical stimulation, detection or ablation. 16. Method for manufacturing a medical electrode, comprising the following steps, (i) Providing a base body on which an electrically conductive first layer is arranged, (ii) Arranging a cover layer on the base body so that the first layer is partially covered by an overhang of the cover layer. 17. Method according to embodiment 16, wherein the overhang comprises a side wall which is arranged at an angle (A) to the surface of the first layer which is (i) less than 80° or (ii) 110° to 170°. 18. Electrode system comprising a plurality of electrodes according to one of embodiments 1 to 14. 19. Method for medical treatment comprising bringing into contact an electrode according to one of embodiments 1 to 14 or an electrode system according to embodiment 18 with a subject. 20. Method for medical diagnosis comprising bringing into contact an electrode according to one of embodiments 1 to 14 or an electrode system according to embodiment 18 with a subject. DETAILED DESCRIPTION

[0007] For each of the embodiments described herein, whose elements "have" or "comprise" a certain feature (e.g., a material), a further embodiment is always considered in which the element in question consists solely of the feature, i.e., it does not include any other components. The word "comprise" or "comprise" is used synonymously with the word "have" or "have" herein.

[0008] If an element in an embodiment is designated in the singular, an embodiment containing several such elements is also considered. The use of a plural term for an element generally also includes an embodiment containing only a single corresponding element.

[0009] Unless otherwise stated or clearly excluded from the context, it is generally possible, and hereby expressly considered, that features of different embodiments may also be present in the other embodiments described herein. Likewise, it is generally considered that all features described herein in connection with a method are also applicable to the products and devices described herein, and vice versa. For the sake of brevity, not all of these considered combinations are explicitly listed in every case. Technical solutions that are known to be equivalent to the features described herein are also generally considered to be within the scope of the invention.

[0010] A first aspect of the invention relates to a medical electrode according to claim 1.

[0011] A medical electrode according to the invention is intended for use on a subject, i.e., on or in the human or animal body. When such an electrode is used as intended, an electrical signal is delivered to and / or received by the body. Therefore, in a preferred embodiment, a medical electrode is configured to deliver and / or receive an electrical signal to the body. For example, nerve or muscle tissue can be functionally stimulated by means of an electrical signal, or such tissue can emit electrical signals that are received by a medical electrode according to the invention. "Functionally stimulated" here means the stimulation of a physiological response, for example, the contraction of a muscle or an action potential of a neuron.Another example is the removal (ablation) of tissue using electrical impulses that can be delivered to the tissue by a medical electrode according to the invention.

[0012] The medical electrode according to the invention comprises a base body. The base body preferably comprises an electrically insulating material which is configured to carry an electrically conductive layer.

[0013] The base body preferably comprises a polymer. In one embodiment, the base body comprises a flexible polymer substrate. A "flexible polymer substrate" is understood to be a polymer body that can be deformed by hand without requiring any special force. The flexible polymer substrate is preferably a polymer film. Examples of materials that can be used in connection with the base body according to the invention include polyester, polyethylene foam, cellulose nonwoven fabric, polyethylene vinyl acetate, polyurethane, epoxy resins, liquid crystal polymers, and polyimide, or mixtures or composites thereof.

[0014] Examples of liquid crystalline polymers include LCP-polyimide, LCP-BT-epoxy, and mixtures thereof. They are commercially available from companies such as Dyconex (Bassersdorf, Switzerland).

[0015] The base body can also comprise multilayer systems, for example, made of different polymers. The base body can, for instance, consist of polyimide and be coated with an epoxy resin. Examples of suitable polymers for the base body also include commercially available solder resists, such as those available from Dyconex.

[0016] The electrode comprises an electrically conductive first layer. This electrically conductive first layer is preferably configured to transmit or receive an electrical signal. The terms "electrically conductive" and "electrically conducting" are used synonymously here and refer to an electrical conductivity of a material as is common and useful in the context of a medical electrode.

[0017] The electrically conductive first layer preferably comprises a metal or alloy. Examples of suitable metals include gold, platinum, nickel, palladium, iridium, titanium, silver, copper, and iron. Examples of suitable alloys include stainless steel, MP35, or a platinum-iridium alloy.

[0018] In some embodiments, the electrically conductive first layer comprises an alloy such as MP35, Ptlr10, Ptlr20, 316L, 301 or Nitinol.

[0019] In one embodiment, the first layer comprises a metal or alloy selected from the group consisting of gold, platinum, stainless steel, nitinol, and a platinum-iridium alloy. Examples of stainless steel include 316L and 301. Examples of platinum-iridium alloys include PtIr10 and PtIr20.

[0020] MP35 is a hardenable nickel-cobalt-based alloy. One variant of MP35 is described in the industry standard ASTM F562-13. In one embodiment, MP35 is an alloy comprising 33 to 37% Co, 19 to 21% Cr, 9 to 11% Mo, and 33 to 37% Ni.

[0021] Ptlr10 is an alloy of 88 to 92% platinum and 8 to 12% iridium.

[0022] PtIr20 is an alloy of 78 to 82% platinum and 18 to 22% iridium.

[0023] 316L is an acid-resistant, CrNiMo austenitic steel with approximately 17% Cr, approximately 12% Ni, and at least 2.0% Mo. A variant of 316L is described in industry standard 10088-2. In one embodiment, 316L is an alloy comprising 16.5 to 18.5% Cr, 2 to 2.5% Mo, and 10 to 13% Ni.

[0024] 301 is a chromium-nickel steel with high corrosion resistance. One variant of 301 is described in the industrial standard DIN 1.4310. In one embodiment, 301 is an alloy comprising 16 to 18% Cr and 6 to 8% Ni.

[0025] Nitinol is a shape-memory nickel-titanium alloy with an ordered cubic crystal structure and a nickel content of approximately 55%, the remainder being titanium. Nitinol exhibits good biocompatibility and corrosion resistance properties. Unless otherwise stated, all percentages are to be understood as mass percent (weight percent).

[0026] The first layer may have a fine structure on its surface, as shown for example in EP 3 108 927A1.

[0027] In one embodiment, the first layer comprises A. Microprotrusions, B. Macroprotrusions, wherein the microprotrusions are arranged on the macroprotrusions, C. a first set of depressions, wherein the first set of depressions comprises at least two longitudinal depressions; D. wherein the macro-projections and the at least two longitudinal depressions are arranged in an alternating pattern, where I. at least 50% of the macroprotrusions have a width, measured along a first direction, in the range of 2.0 µm to 40.0 µm; II. at least 50% of the microprotrusions have a width, measured along the first direction, in the range of 0.001 µm to 1.000 µm.

[0028] A cover layer is arranged on the base body. This cover layer has an overhang that partially, but not completely, covers the electrically conductive first layer. The cover layer preferably consists of an electrically non-conductive material, such as a polymer. Examples of suitable polymers include compounds selected from the group consisting of liquid-crystalline polymers, medical-grade silicone, epoxy resins, polyurethane, polyethylene, polyacrylic, P(M)MA, ABS, PVDF, polyester, polyamide, polyimide, SEBS, PEEK, PPS, PEVA, PEN, polysulfones, and copolymers thereof.

[0029] The base body and the top layer can be made of the same material or of different materials.

[0030] In one embodiment, the top layer covers, at least partially, both the base body and the first layer.

[0031] Preferably, the top layer covers the edge of the electrically conductive first layer, where "edge" refers to the outer edge of the first layer, which in a cross-sectional view is arranged distal to the base body, i.e., points in the direction opposite to the base body and has a maximum distance to the center of the first layer.

[0032] In some embodiments, the edge of the first layer is essentially completely covered by the top layer (as shown in the figures).

[0033] In a preferred embodiment, the top layer completely covers the edge of the electrically conductive first layer.

[0034] The overlapping arrangement of the top layer with respect to the electrically conductive first layer, as described above, provides several technical advantages. It stabilizes the electrically conductive first layer. For example, the overhang protects the first layer from delamination, i.e., separation from the substrate. Furthermore, the overhang protects against diffusion between the first layer and the substrate when the first layer is coated using a liquid coating process, as described in more detail elsewhere herein. Overall, the underlying layers are protected from external influences, such as oxidation, during the manufacture and use of the electrode.

[0035] The top layer includes a depression. This depression may provide access to the electrically conductive first layer. The depression may be bounded by the side walls of the overhang. The depression can have different geometries. For example, the depression may taper towards the base body in a funnel shape, or it may widen towards the base body. This can be caused by different angles of the overhang's side walls to the surface of the first layer.

[0036] In principle, the side walls can be arranged at any angle. For example, the overhang can be arranged at an angle of 90° or approximately 90°, for example 85° to 95°, to the surface of the first layer. However, it can be advantageous if this angle deviates significantly from 90°.

[0037] For example, the overhang may be arranged at an angle of less than 80° to the surface of the first layer, so that the depression widens towards the base body, forming a cavity or hollow. Alternatively, this angle may be, for example, 110° to 170°, so that the depression tapers towards the base body, giving it a funnel shape. This angle is defined as shown in the accompanying drawings (there designated as angle 'A'), i.e., it is measured between a side wall of the overhang and the surface of the first layer on the 'inner side', i.e., the side of the depression.

[0038] These two variants can offer several advantages. An angle greater than 90° (a "funnel shape"), for example, approximately 135°, can protect the top layer from mechanical damage because, compared to right-angled, steep side walls, there are fewer exposed, protruding edges on the outward-facing side of the top layer. Therefore, lower shear forces occur at the surface than with a right-angled shape. Protection against delamination of the top layer and against the ingress of contaminants can also be improved with this "funnel shape." Furthermore, with the same size accessible electrode surface area of ​​the first layer, or its conductive coating, better charge exchange with the external medium via diffusion can occur, as explained in more detail below with reference to the drawings.In this context, "diffusion" refers to the movement of charge carriers within an external medium, specifically the exchange of charge between the electrode and the surrounding medium. This movement can be mediated, for example, by applying an electrical voltage. Therefore, the term "diffusion" is not limited to Brownian motion but generally describes the movement of charge carriers, such as ions, within a liquid medium to mediate charge exchange or electric current flow.

[0039] The "funnel shape" allows the electrode to be brought into better contact with the tissue of a subject.

[0040] The external medium can be, for example, a subject's tissue fluid. To investigate the charge exchange with the electrode's external medium, an in-vitro measurement can also be performed in physiological saline solution or another saline solution such as a potassium hydroxide solution, as is common practice in the field.

[0041] When the angle of the side walls is less than 90°, the overhang forms a partially enclosed area above the first layer, which acts as a "dead volume." This results in stronger shielding of the first layer from the external medium. This can be advantageous for making the electrode less susceptible to interference signals or for "tapping" diffusing particles within the depression, thereby improving their detection in certain cases.

[0042] In some embodiments, the medical electrode further comprises an electrically conductive second layer arranged on top of the first layer. The first layer can be coated, for example, with a conductive polymer or a metal, alloy, or metal oxide. Suitable metals include platinum, gold, or other medically compatible precious metals and alloys. Iridium oxide is an example of a suitable metal oxide.

[0043] The conductive polymer may, for example, comprise a polymer selected from the group consisting of a polyacetylene, a polyvinyl alcohol, a polyfluorene, a polyphenylene, a polyphenylenevinylene, a polypyrene, a polyazulene, a polynaphthalene, a polypyrrole, a polycarbazole, a polyindole, a polyazepine, a polyaniline, a polyacene, a polythiophene, a polythiophenevinylene, a polyphenylene sulfide, a polypyridine, or functionalized derivatives, precursors, or mixtures thereof. Examples of conductive polymers are described in WO 2015 / 031 265 A1. In some embodiments, the conductive polymer comprises poly-3,4-ethylenedioxythiophene (PEDOT). In one embodiment, the conductive polymer comprises PEDOT:PSS, i.e., PEDOT complexed with polystyrenesulfonate. In one embodiment, the conductive polymer comprises PEDOT:PSS and another polymer.One example of such a polymer is PVP (polyvinylpyrrolidone).

[0044] Suitable conductive polymers are commercially available, for example, the products CLEVIOS and AMPLICOAT from Heraeus (Hanau, Germany). AMPLICOAT is particularly advantageous for use in implantable medical devices. The term AMPLICOAT here refers both to the commercially available precursor substance and to the polymer produced from it.

[0045] Preferably, the first layer and the second layer comprise different materials. For example, the first layer may comprise platinum or a platinum-iridium alloy, and the second layer may comprise PEDOT or a PEDOT-containing composition, in particular AMPLICOATE.

[0046] In another embodiment, the first layer can comprise platinum or a platinum-iridium alloy, and the second layer can comprise an iridium oxide layer.

[0047] In one embodiment, the first layer comprises gold, and the second layer comprises PEDOT.

[0048] In one embodiment, the first layer comprises platinum, and the second layer comprises PEDOT.

[0049] In one embodiment, the first layer comprises a platinum-iridium alloy, and the second layer comprises PEDOT. The second layer may, for example, comprise a PEDOT-containing composition, in particular AMPLICOATE, as described in more detail elsewhere herein. In another embodiment, the first layer comprises gold, and the second layer comprises AMPLICOATE.

[0050] In one embodiment, the first layer comprises gold, and the second layer comprises iridium oxide.

[0051] In one embodiment, the first layer comprises platinum, and the second layer comprises iridium oxide.

[0052] In one embodiment, the first layer comprises a platinum-iridium alloy, and the second layer comprises iridium oxide. In some embodiments, a layer comprising iridium oxide may be produced using a thermally decomposable iridium-containing composition, as described in more detail elsewhere herein.

[0053] In one embodiment, the first layer comprises gold, and the second layer comprises platinum. In another embodiment, the first layer comprises platinum, and the second layer comprises platinum. In this case, the two platinum layers can, for example, have different structures, such as different surface finishes and / or porosities.

[0054] In one embodiment, the first layer comprises a platinum-iridium alloy, and the second layer comprises platinum. The second platinum layer may be produced using a thermally decomposable platinum-containing composition, as further described elsewhere herein.

[0055] Liquid coating processes can be used to produce the second layer. AMPLICOAT can preferably be applied by electrodeposition.

[0056] The conductive polymers described herein can also be doped with additives.

[0057] Doping can increase the conductivity of a polymer and create a lower energy threshold for conductivity. Dopants can also help to precisely control conductivity properties. Many methods and materials are useful for doping and should be familiar to those skilled in the art. These include, among others, chloride, polystyrenesulfonate (PSS), dodecylbenzenesulfonate, polystyrenesulfonate, naphthalenesulfonate, and lithium perchlorate.

[0058] The electrically conductive second layer is preferably deposited by an electrodeposition process (also known as electropolymerization or electrodeposition), as is known to those skilled in the art. Electrodeposition is the deposition of a material by applying an electrical potential between two conductive materials (or electrodes) in a liquid medium containing charged substances. In various embodiments, the materials are electroplated at the anode (i.e., at the electrode where monomer oxidation takes place). A typical apparatus for carrying out electrodeposition comprises the following: an anode, a cathode, and often a reference electrode, each separated by an electrolyte (e.g., an ion-containing solution), and a potentiostat that monitors / adjusts the voltages / currents at the various electrodes.Electrochemical deposition can be carried out under various electrochemical conditions, including the following: (a) constant current, (b) constant voltage, (c) current scan / sweep, e.g., over a single or multiple scans / sweeps, (d) voltage scan / sweep, e.g., over a single or multiple scans / sweeps, (e) current square waves or other current pulse waveforms, (f) voltage square waves or other voltage pulse waveforms, and (g) a combination of different current and voltage parameters.

[0059] The electroplating process can be controlled to deposit layers of conductive polymer with different thicknesses.

[0060] The second layer can completely or partially cover the exposed portion of the first layer. In this context, the "exposed portion of the first layer" refers to that part of the first layer which is not directly covered by the top layer. The second layer can be applied in a geometric shape that differs from the surface shape of the first layer. For example, the exposed portion of the first layer may have a square surface, and the surface of the second layer may have a circular shape.

[0061] According to the invention, the second layer is arranged exclusively within the recess of the top layer. This means that the second layer does not protrude from the recess and, in particular, does not cover the surface of the top layer.

[0062] Furthermore, according to the invention, the outward-facing surface of the second layer is spaced apart from the outward-facing surface of the top layer. This means that the second layer covers the exposed part of the first layer, for example, completely, but does not completely fill the recess. Rather, a free area remains within the recess, below the outward-facing surface of the top layer. This provides better protection for the second layer against mechanical damage. This is particularly advantageous if the second layer is mechanically sensitive, for example, if the second layer comprises an electrically conductive polymer.

[0063] The present invention is well suited for application with flexible substrates. In some embodiments, the substrate therefore comprises a flexible polymer substrate. Examples of such flexible polymer substrates are known to those skilled in the art under the term "flex PCB" and are described in more detail elsewhere herein.

[0064] This allows for the production of flexible electrodes, which pose a lower risk of injury to patients and can be positioned better in the body than electrodes with a rigid structure.

[0065] In some embodiments, the medical electrode further comprises a conductive trace that is electrically connected to the first layer. This conductive trace serves to electrically contact the first layer. For example, an electrical signal can be transmitted to the first layer via the conductive trace, so that the signal can then be transmitted from the first layer to a subject to produce electrical stimulation. The conductive trace can be directly or indirectly connected to the first layer via other elements. For example, the conductive trace can comprise copper and be electrically connected to the first layer via a barrier layer comprising nickel.

[0066] In one embodiment, the overhang is arranged and configured to mechanically stabilize the first layer. This can be achieved, for example, by appropriately selecting the angle of the side walls with respect to the first and second layers, as described in more detail elsewhere herein. This can, for example, protect the edge regions of the first layer from mechanical stress.

[0067] In one embodiment, the overhang is arranged and configured to allow an electrical charge exchange between a liquid outer medium and the layer by means of diffusion from different directions. For example, this can be achieved by appropriately selecting the angle of the side walls with respect to the first layer, as described herein. This can be particularly advantageous for detection applications, as it can increase the sensitivity of measurements in some cases.

[0068] In one embodiment, the overhang is arranged and configured to protect the base body from the ingress of liquid. For example, this can be achieved by appropriately selecting the angle of the side walls with respect to the first layer or second layer, as described herein.

[0069] The first and / or second layer can also be modified with additional reagents, such as enzymes or antibodies. This allows non-electrogenic analytes, such as proteins or uncharged organic substances, to be detected using the electrode by coupling them to an electrochemical reaction. Such methods are commonly used, for example, for blood glucose determination. In this context, the outermost layer of the first or second layer can be modified.

[0070] Another aspect of the invention relates to an electrode system comprising several electrodes described herein. Preferably, the system comprises several of the electrodes described herein, which can be electrically addressed independently of one another. This allows, for example, different locations of a subject's target tissue to be electrically stimulated or detected independently of one another.

[0071] Another aspect of the invention relates to the use of a medical electrode described herein in a device designed for electrical stimulation, detection, or ablation. For example, the device may be a catheter for electrophysiological stimulation or tissue ablation. Other possible applications include, for example, pacemakers, implantable cardioverter-defibrillators, defibrillators, and cardiac resynchronization therapy devices, as well as implantable electrodes for neuromodulation, cardiac stimulation, deep brain stimulation, spinal cord stimulation, or gastric stimulation. Furthermore, the electrodes described herein can be used for ECG or EEG measurements, i.e., for investigating cardiac or brain function. In addition, the electrodes described herein can be used for the detection of certain substances, such as proteins or metabolites.In some embodiments, the application of an electrode described herein includes both diagnostic and therapeutic functions. For example, a diagnostic function can be used to monitor, control, or verify the effect of a therapeutic function, either simultaneously or at a later time.

[0072] The present invention also relates to methods for medical treatment and methods for medical diagnosis in which the medical electrodes described herein are brought into contact with a patient. Such a method may, for example, include the application of an electrode described herein for neuromodulation, cardiac stimulation, deep brain stimulation, spinal cord stimulation, or gastric stimulation. Examples of medical diagnostic methods include ECG or EEG measurements.

[0073] Another aspect of the invention relates to a method for manufacturing a medical electrode, comprising the following steps, (i) Providing a base body on which an electrically conductive first layer is arranged, (ii) Arranging a cover layer on the base body such that the first layer is partially covered by an overhang of the cover layer, the cover layer further comprising a depression, the second layer being arranged exclusively within the depression, and the outward-facing surface of the second layer being spaced apart from the outward-facing surface of the cover layer, leaving a free area within the depression.

[0074] In one embodiment, the method includes structuring the surface layer using laser ablation. Alternatively, conventional mechanical methods can be used to process the geometry of the surface layer, or the surface layer can be produced directly using a forming process, such as injection molding, thermoplastic forming, or 3D printing.

[0075] The method may further include suitable steps for arranging the individual components of the electrode in order to produce the embodiments of the electrode described herein. The features of all embodiments of the electrode described herein are therefore also applicable to the method described herein.

[0076] For example, in the method according to the invention, the top layer can be arranged on the base body such that the overhang includes a side wall which is arranged at an angle to the surface of the first layer which is (i) less than 80° or (ii) 110° to 170°. EXAMPLES

[0077] The invention is further illustrated below by means of examples, which, however, are not to be understood as limiting. It will be apparent to those skilled in the art that other equivalent means can be used in a similar manner instead of the features described here. EXAMPLE 1 - SWIPE TEST

[0078] Medical electrodes were fabricated, each consisting of a gold base layer and a second layer of amplicoat (1 micrometer thick). The first electrode type, A, comprised a gold base embedded in PEEK and had no topcoat. The second electrode type, B, comprised a polyimide base layer, a gold base layer (5 µm thick), and a topcoat applied to the first layer and covering its edge. Using a standard foam-tipped swab, the electrode surfaces were wiped with a defined load of up to 203 g, i.e., the swab was moved laterally across the electrode surfaces with a defined force. While delamination of the gold layer was observed in the first electrode type, A, starting at a load of approximately 118 g, no delamination was detectable in the second electrode type, B, even at a load of 203 g. FIGURES Fig. Figure 1 shows an exemplary cross-sectional view of an electrode according to a first embodiment of the invention. A first electrically conductive layer 102 is arranged on a base body 101. The first layer 102 is electrically contacted by means of a conductor track 104, which runs inside the base body 101. The base body 101 and the first layer 102 are partially covered by a cover layer 103. The cover layer 103 includes a recess 108, which is formed by the side walls of the cover layer 103 and the first layer 102. The cover layer 103 includes a projection 107, which partially extends beyond and covers the surface of the first layer 102. This projection protects the outer edge region of the first layer 102 and the underlying layers from mechanical damage and the ingress of the external medium. This provides better protection for the electrode against corrosion and delamination of the first layer 102.In this embodiment, the projection 107 has a rectangular geometry. The exposed surface of the first layer 102 can, for example, have a circular or rectangular geometry. Accordingly, the electrode can have one or more projections 107. If the electrode has several projections 107, these are preferably of the same shape. In this example, the first electrically conductive layer 102 consists of Ptlr10. The edge 109 of the first layer is completely covered by the projections 107 of the cover layer 103. Fig. Figure 2 shows an example of an electrode according to a second embodiment of the invention in a cross-sectional view. The structure of the electrode is similar to that described in Fig. Figure 1 shows the projection 107, which includes an inclined side wall 106. The side wall 106 is arranged at an angle A to the surface of the cover layer 103, which deviates significantly from 90°. This angle A is always defined here as being measured on the "inner side" of the cover layer, i.e., not in the direction of the nearest edge of the cover layer. An obtuse angle A (i.e., A greater than 90°) therefore means that the horizontal cross-section of the recess 108 tapers downwards (i.e., towards the first layer, away from the outside of the cover layer). This eliminates, compared to the Fig. In the embodiment shown in Figure 1, the outwardly facing right-angled edges of the cover layer 103 are susceptible to damage. If, for example, the side wall 106 experiences a force acting parallel to the base body, the force transmission to the interface between the cover layer 107 and the first layer 102 is reduced, resulting in higher mechanical stability of the cover layer 107. Furthermore, the recess 108 acquires a funnel-shaped geometry. Fig. Figure 3 illustrates the charge exchange of the electrode according to Fig. 1 with the external medium. Due to the right-angled geometry of the projection 107, the movement of the charge carriers in the external medium, which in Fig. 3 is represented by arrows, in parallel flow direction, perpendicular to the surface of the first layer 102. Fig. Figure 4 illustrates the charge exchange of the electrode according to Fig. 2 with the external medium. Due to the funnel-shaped geometry of the well 108, the movement of the charge carriers in the external medium, which in Fig. 4 is shown by arrows, in a hemispherical flow direction, i.e. the charge exchange with the external medium can take place more effectively due to the sloping side wall 106, since the electrode has a larger “draw-in area”. Fig. Figure 5 shows an example of an electrode according to a third embodiment of the invention in a cross-sectional view. In contrast to the ones described in Fig. 1 and Fig. In the two embodiments shown, the angle A between the projection 106 and the surface of the first layer 102 is less than 90°, i.e., the cover layer 107 has an undercut in the region of the surface of the first layer 102. This provides greater shielding of the edge regions of the first layer 102 from the external medium. This allows, for example, a longer residence time of analytes near the electrode surface. In this embodiment as well, the cover layer 103 covers an edge region of the first layer 102, thereby protecting the first layer 102 from damage. Fig. Figure 6 shows an exemplary cross-sectional view of an electrode according to a further embodiment of the invention. Here, a second layer 105 is arranged on the first layer 102. In this example, the first layer 102 consists of gold. The second layer 105 consists of Amplicoat, a conductive polymer comprising PEDOT. The second layer 105 is arranged exclusively within the recess of the top layer, i.e., it does not extend over the outwardly facing surface of the top layer 103. In this example, the second layer 105 does not completely fill the recess: rather, the outwardly facing surface of the second layer 105 is spaced apart from the outwardly facing surface of the top layer 103, leaving a free space in the recess 108. In this way, i.e.,The recessed arrangement of the second layer 105 within the depression 108 protects the second layer 105 from mechanical damage. Fig. Figure 7 shows an exemplary system with several electrodes according to the invention, which is depicted in a top view. Such a system can comprise any of the embodiments described herein. Several electrodes are arranged at uniform intervals as a field. In this example, the angle A between the projection 106 and the surface of the first layer 102 is greater than 90°, i.e., the recess 108 has a funnel-shaped form, as also shown in Figure 7. Fig. Figure 2 shows the side wall 106, which is shown hatched. The projection 106 completely covers the edge of the first layer 102, but leaves the central area of ​​the first layer 102 free, so that it remains accessible to the external medium. Each of the six electrodes is connected by means of a conductor (in Fig.(7 not shown) electrically contacted and addressable independently of the other electrons. Reference symbol list 101 Basic shapes 102 first shift 103 Top layer 104 conductor track 105 second shift 106 side wall 107 lead 108 In-depth study 109 Edge of the first layer A Angle

Claims

[1] Medical electrode comprising a base body (101) on which an electrically conductive first layer (102) and a cover layer (103) are arranged, the cover layer comprising an overhang (107) which partially covers the first layer (102), and an electrically conductive second layer (105) which is arranged on the first layer (102), the second layer (105) comprising an electrically conductive polymer selected from the group consisting of a polyacetylene, a polyvinyl alcohol, a polyfluorene, a polyphenylene, a polyphenylene vinylene, a polypyrene, a polyazulene, a polynaphthalene, a polypyrrole, a polycarbazole, a polyindole, a polyazepine, a polyaniline, a polyacene, a polythiophene, a polythiophene vinylene, a poly-p-phenylene sulfide, a polypyridine or functionalized derivatives, precursors or mixtures thereof;wherein the top layer (103) further comprises a recess (108), wherein the second layer (105) is arranged exclusively within the recess (108), and wherein the outwardly facing surface of the second layer (105) is spaced apart from the outwardly facing surface of the top layer (103), leaving a free area within the recess (108). [2] Medical electrode according to claim 1, wherein the recess (108) tapers or widens towards the base body (101). [3] Medical electrode according to any of the preceding claims, wherein the overhang (107) comprises a side wall (106) which is arranged at an angle (A) to the surface of the first layer (102) which is (i) less than 80° or (ii) 110° to 170°. [4] Medical electrode according to any of the preceding claims, wherein the electrically conductive polymer comprises PEDOT. [5] Medical electrode according to any of the preceding claims, wherein the base body (101) comprises a flexible polymer substrate. [6] Medical electrode according to one of the preceding claims, further comprising a conductor track (104) which is electrically conductively connected to the first layer (102). [7] Medical electrode according to one of the preceding claims, wherein the overhang (107) is arranged and configured to mechanically stabilize the first layer (102). [8] Medical electrode according to one of the preceding claims, wherein the overhang (107) is arranged and configured to enable an electrical charge exchange between a liquid external medium and the first layer (102) and / or optionally the second layer (105) from different directions. [9] Medical electrode according to one of the preceding claims, wherein the overhang (107) is arranged and configured to protect the base body (101) from the ingress of liquid. [10] Medical electrode according to one of the preceding claims, wherein the edge (109) of the first layer (102) is substantially completely covered by the cover layer (103). [11] Device which is configured for electrical stimulation, detection or ablation, comprising a medical electrode according to any of the preceding claims. [12] Method for manufacturing a medical electrode, comprising the following steps, (i) Providing a base body (101) on which an electrically conductive first layer (102) and an electrically conductive second layer (105) are arranged, wherein the second layer (105) is arranged on the first layer (102), and wherein the second layer (105) comprises an electrically conductive polymer selected from the group consisting of a polyacetylene, a polyvinyl alcohol, a polyfluorene, a polyphenylene, a polyphenylene vinylene, a polypyrene, a polyazulene, a polynaphthalene, a polypyrrole, a polycarbazole, a polyindole, a polyazepine, a polyaniline, a polyacene, a polythiophene, a polythiophene vinylene, a polyphenylene sulfide, a polypyridine or functionalized derivatives, precursors or mixtures thereof. (ii) Arranging a cover layer (103) on the base body such that the first layer is partially covered by an overhang (107) of the cover layer, the cover layer (103) further comprising a depression (108), the second layer (105) being arranged exclusively within the depression (108), and the outward-facing surface of the second layer (105) being spaced apart from the outward-facing surface of the cover layer (103) so that a free area remains within the depression (108). [13] Method according to claim 12, wherein the overhang (107) comprises a side wall (106) which is arranged at an angle (A) to the surface of the first layer (102) which is (i) less than 80° or (ii) 110° to 170°.

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