Artificial cochlea electrode lead and method of manufacturing the same

Abstract

An electrode lead for artificial implantation in a cochlear system includes a tube having an interior volume and an outer peripheral surface; a plurality of stimulating electrodes disposed on a distal portion of the electrode lead; a ground electrode disposed on a proximal portion of the electrode lead for providing a current return path for stimulating current generated by the plurality of stimulating electrodes, wherein the ground electrode is annular and secured to the outer peripheral surface around the outer peripheral surface of the tube; and a ground lead extending within the interior volume of the tube to the ground electrode and electrically connected to the ground electrode through an opening in the wall of the tube. The ground electrode includes a first end portion, a central portion axially adjacent the first end portion, and a second end portion axially adjacent the central portion, wherein an outer surface of the central portion is radially elevated relative to an outer surface of the first end portion and an outer surface of the second end portion so as to form a step at a boundary between the first end portion and the central portion and a step at a boundary between the second end portion and the central portion, respectively.

Description

TECHNICAL FIELD

[0001] The present invention relates to an electrode lead for a cochlear implant system and a method of manufacturing the same. BACKGROUND

[0002] Cochlear implant systems are used to provide restoration and / or improvement of hearing loss suffered by a cochlear implant patient using a cochlear implant system. A key component of a cochlear implant system is an electrode lead which is inserted into the cochlea of a patient. A distal portion of the electrode lead is provided with a plurality of stimulation electrodes for applying stimulation current to auditory nerve tissue within the cochlea, the stimulation current being supplied via electrode leads which extend through the electrode lead and electrically connect the stimulation electrodes to the cochlear implant implanted in the patient at a proximal end of the electrode lead. A proximal portion of the electrode lead can be provided with one or more ground electrodes for providing a current return path for the stimulation current applied by the stimulation electrodes; alternatively, the ground electrodes can be provided separately from the electrode lead. The ground electrodes can be designed as a ring electrode which is arranged on the electrode lead and electrically connected to the cochlear implant via a ground lead extending within the proximal portion of the electrode lead. An example of such a cochlear implant system is described in WO 2019 / 045747 Al.

[0003] Another example of a cochlear implant electrode lead with a ground ring electrode is known from US 9,561,361 Bl, wherein the ring electrode is arranged on a tube of large diameter, the stimulation electrode leads being helically wound around and through the interior of the tube which is backfilled with silicone; while the ground lead is helically wound around and through the center of the helically wound stimulation leads. The ring electrode is provided with silicone collars on each side for smoothing the profile of the tube, fixing the ring electrode in place, and reducing the likelihood of kinking of the tube. The shape of the ring electrode is a hollow cylinder. The ground lead exits from an opening in the sidewall of the tube and is electrically connected to the ring electrode arranged on top of the tube.

[0004] The ring of the ground electrode and the ground lead can be susceptible to liquid ingress, in particular when the electrode lead is subjected to pressure near the ring or the fan tail; liquid ingress can result in long-term overestimation of the electrode impedance. Furthermore, the silicone collars on both sides of the ring electrode can be susceptible to variations in the application of the silicone due to the lack of consistent boundaries of the applied silicone. SUMMARY

[0005] It is an object of the present invention to provide an electrode lead for a cochlear implant system with a ground electrode which has a relatively high resistance to liquid ingress and which can be manufactured in a relatively consistent and efficient manner. It is a further object to provide a method of manufacturing such an electrode lead.

[0006] According to the application, these objects are achieved by the electrode lead defined in claim 1 or claim 14, respectively, and by the manufacturing method defined in claim 15.

[0007] The electrode lead according to claim 1 has the advantage that the reliability and the manufacturability of the electrode lead can be improved by providing the central portion of the ground ring electrode with an outer surface that is radially raised with respect to the outer surfaces of the adjacent first end portion and the second end portion of the ground ring electrode so as to form a step at the border between the central portion and the first end portion and the second end portion, respectively, or by providing the end portions of the ground ring electrode with a ring-like marking structure. In particular, the step or the marking structure provides a border for applying the silicone to the end portions of the ground ring electrode, thereby improving the consistency of the silicone application of the silicone cover layer of the adjacent outer surfaces of the end portions of the ground ring electrode and the tube.

[0008] According to one embodiment, the outer diameter of the central portion of the ground electrode can be substantially constant axially over the entire length of the central portion, such that the outer surface of the central portion is substantially cylindrical.

[0009] According to one embodiment, the outer diameter of the first end portion of the ground electrode can be substantially constant axially over the entire length of the first end portion, and the outer diameter of the second end portion of the ground electrode can be substantially constant axially over the entire length of the second end portion.

[0010] According to one embodiment, the first end portion and the second end portion of the ground electrode can have substantially the same outer diameter.

[0011] According to one embodiment, the first end portion and the second end portion of the ground electrode and the central portion of the ground electrode can all have the same inner diameter.

[0012] According to one embodiment, the axial dimension of the first end portion of the ground electrode can be substantially the same as the axial dimension of the second end portion of the ground electrode.

[0013] According to one embodiment, the ground electrode can comprise at least one slot for receiving an end portion of the ground wire so as to attach the ground wire to the ground electrode.

[0014] According to one embodiment, the at least one slot can be provided on the edge of the first end portion and / or the second end portion of the ground electrode, or the at least one slot can be provided in the central portion of the ground electrode.

[0015] According to one embodiment, the first end portion and the second end portion of the ground electrode can each be covered by a silicone cover layer that extends from the outer surface of the tube to the step at the border between the central portion and the respective first end portion or second end portion of the ground electrode so as to seal the ground electrode to the tube.

[0016] According to one embodiment, the outer surface of each of the silicone cover layers can be substantially flush with the outer surface of the central portion of the ground electrode.

[0017] According to one embodiment, the first end portion and / or the second end portion of the ground electrode can comprise at least one opening for silicone injection in order to anchor the silicone cover layer to the respective first or second end portion of the ground electrode.

[0018] According to one embodiment, the at least one opening can comprise at least one slot provided on the edge of the first end portion and / or the second end portion, or the at least one opening can comprise at least one hole.

[0019] According to one embodiment, the outer surface of the first end portion and / or the second end portion of the ground electrode can be provided with a surface structure, such as circumferential ribs or circumferential channels forming partial threads, in order to improve the adhesion of the silicone cover layer.

[0020] According to one embodiment, the outer surface of the first end portion and / or the second end portion of the ground electrode can be roughened in order to improve the adhesion of the silicone cover layer.

[0021] According to one embodiment, the step at the border between the first end portion and the central portion and / or the step at the border between the second end portion and the central portion can be provided with a recess on the outer surface of the central portion, the recess extending axially into a portion of the central portion that is elevated relative to the first and second end portions of the ground electrode, and the recess can be configured to allow silicone injection in order to anchor the silicone cover layer of the respective first or second end portion at the step.

[0022] According to one embodiment, at least a portion of the inner surface of the ground electrode can comprise a layer of silicone adhesive sandwiched between the outer surface of the tube and the inner surface of the ground electrode.

[0023] According to one embodiment, the ground lead can be covered with PPSU.

[0024] According to one embodiment, the electrode leads for the plurality of stimulating electrodes can extend through the internal volume of the tube in a helically wound configuration, while the ground lead can be wound radially relative to the electrode leads.

[0025] According to one embodiment, the tube can comprise a first tube portion and a second tube portion, which can be axially aligned with each other and can be axially abutted to each other, thereby forming a circumferential gap between the two, the gap being filled with silicone and being surrounded by the ground electrode.

[0026] According to one embodiment, the gap can form an opening of the tube, through which the ground lead extends to the ground electrode.

[0027] According to one embodiment, the inner volume of the tube can be backfilled with a fast-curing silicone glue.

[0028] According to one embodiment, the outer surface of the central portion can be polished or laser textured.

[0029] According to one embodiment, the ground electrode can be made of Pt, Ti, PtIr alloy or Ti alloy.

[0030] According to one embodiment, the ratio of the outer surface area of the central portion of the ground electrode to the total outer surface area of the ground electrode can be 0.50 to 0.75.

[0031] According to one embodiment of the electrode lead according to claim 14, each annular marker structure can comprise two parallel rings which can be axially spaced apart. For example, each annular marker structure can be formed by engraving or laser processing the surface portion.

[0032] The manufacturing method defined in claim 15 has the advantage that it allows to particularly consistently and efficiently manufacture the electrode lead. In particular, the double tube configuration with the first tube portion and the second tube portion abutting each other inside the ground ring electrode allows to completely assemble the sub-assembly of the ground ring electrode and the ground wire connected to the ground ring electrode, the ground wire extending through the gap between the first tube portion and the second tube portion, whereby it can be avoided that the ground wire needs to be pulled through the inner diameter of the tube and out through an opening cut in the tube wall.

[0033] According to one embodiment, the ground wire can be radially wound with the electrode wire. This improves manufacturability and reduces potential process failures.

[0034] According to one embodiment, the ground wire can be made of Pt and covered with PPSU, whereby the bonding to the ground wire and the silicone backfill of the tube can be improved.

[0035] According to one embodiment of the method according to claim 15, the outer surface of the central portion of the ground electrode is radially elevated relative to the outer surface of the first end portion and the outer surface of the second end portion of the ground electrode so as to form a step at the border between the first end portion and the central portion and at the border between the second end portion and the central portion, respectively, and the silicone cover layer is applied on the outer surfaces of the first and second end portions of the ground electrode such that the outer surface of each silicone cover layer is approximately flush with the outer surface of the central portion of the ground electrode.

[0036] According to one embodiment of the method according to claim 15, each of the first end portion and the second end portion comprises an annular marker structure, and the silicone cover layer is applied on the outer surfaces of the first and second end portions of the ground electrode in such a way that the silicone cover layer does not axially extend to the central portion beyond the annular marker structure.

[0037] According to one embodiment of the method according to claim 15, the ground wire is radially wound on the mandrel together with the electrode wires.

[0038] The preferred embodiments of the present application are defined in the dependent claims. BRIEF DESCRIPTION OF DRAWINGS

[0039] In the following, examples of the present application will be described with reference to the accompanying drawings, in which:

[0040] Figure 1 An example of an artificial cochlea system is schematically shown;

[0041] Figure 2 A partial cut-away perspective view of an example of a ground ring electrode mounted on an artificial cochlea lead is shown;

[0042] Figure 3 A cross-sectional view of the ground electrode of Figure 2 is shown;

[0043] Figure 4 is a similar view as Figure 2 , wherein only the ground ring electrode is shown without the tube being partially cut away;

[0044] Figures 5A to 5J A different example of a ground ring electrode is shown;

[0045] Figures 6A to 6F Steps of an example of an assembly process of a cochlea lead with a ground ring electrode are shown;

[0046] Figure 7 A double tube concept used in the manufacturing process of a cochlea lead with a ground ring electrode is shown;

[0047] Figure 8 is a side view of an example of an artificial cochlea with an electrode lead; and

[0048] Figure 9 Another example of a ground ring electrode is shown. DETAILED DESCRIPTION

[0049] As described below, the term "distal" refers to the part or member that is further away from the artificial cochlea (hermetically sealed housing) or the surgeon implanting the artificial cochlea, while the term "proximal" refers to the part or member that is closer to the artificial cochlea or the surgeon implanting the artificial cochlea. In the following, the term "substantially" is to be understood as "within ± 10%".

[0050] The terms "ground electrode", "ring electrode" and "ground ring electrode" are used in the following in an interchangeable manner to refer to a ring-shaped ground electrode.

[0051] Figure 1 An exemplary cochlear implant system 100 is shown. As shown, the cochlear implant system 100 may include a microphone 102, a sound processor 104, a head-mounted device 106 in which a coil is disposed, a cochlear implant 108, and electrode leads 110.

[0052] Electrode lead 110 includes an array of stimulating electrodes 112 (also referred to as intracochlear electrodes) disposed on the distal portion of electrode lead 110. These stimulating electrodes are configured to be located within the cochlea and are capable of stimulating the cochlea after the distal portion of electrode lead 110 is inserted into the cochlea. As shown, electrode lead 110 also includes a grounding electrode 120 (also referred to as a ring electrode) disposed on the proximal portion of electrode lead 110. This grounding electrode is configured to provide a current return path for the stimulating current generated by the stimulating electrodes 112 and remains outside the cochlea after electrode lead 110 is inserted into the cochlea. Although Figure 1 A single grounding electrode 120 is shown, but it will be appreciated that multiple grounding electrodes 120 may be arranged on the proximal portion of the electrode lead 110 to serve a particular embodiment. As shown, the electrode lead 110 may be pre-bent to suitably conform to the spiral shape of the cochlea. Additional or alternative components may be included within the cochlear implant system 100 to serve a particular embodiment.

[0053] As shown in the figure, the cochlear implant system 100 may include various components configured to be located outside the patient, including but not limited to a microphone 102, a sound processor 104, and a head-mounted device 106. The cochlear implant system 100 may also include various components configured to be implanted inside the patient, including but not limited to an artificial cochlear implant 108 and electrode leads 110.

[0054] Microphone 102 can be configured to detect audio signals presented to the user. Microphone 102 can be implemented in any suitable manner. For example, microphone 102 may include a microphone configured to be placed within the auricle near the entrance to the ear canal, such as Advanced Bionics' T-MIC. TM Microphone. Such a microphone can be held within the auricle near the ear canal entrance by a bracket or handle attached to an ear hook configured for selective attachment to the sound processor 104. Additionally or alternatively, the microphone 102 may be implemented by one or more microphones disposed within the headset 106, one or more microphones disposed within the sound processor 104, one or more beamforming microphones, and / or any other suitable microphone to serve a particular implementation.

[0055] The sound processor 104 (i.e., one or more components included within the sound processor 104) can be configured to direct the artificial cochlea 108 to generate and apply electrical stimulation (also referred to herein as "stimulation current") representative of one or more audio signals (e.g., one or more audio signals detected by the microphone 102 input by way of an auxiliary audio input port, input by way of a clinician programming interface ("CPI") device, etc.) to one or more stimulation sites associated with a patient's auditory pathway (e.g., an auditory nerve). Exemplary stimulation sites include, but are not limited to, one or more locations within the cochlea, cochlear nucleus, hypothalamus, and / or any other nuclei in the auditory pathway. To this end, the sound processor 104 can process the one or more audio signals in accordance with a selected sound processing strategy or program to generate appropriate stimulation parameters for controlling the artificial cochlea 108. The sound processor 104 can be housed within any suitable housing (e.g., a behind-the-ear ("BTE") unit, a wearable device, the headpiece 106, and / or any other sound processing unit that can serve a particular implementation).

[0056] In some examples, the sound processor 104 can wirelessly transmit stimulation parameters (e.g., in the form of data words included in a forward telemetry sequence) and / or power signals to the artificial cochlea 108 by way of a wireless communication link 114 (e.g., a wireless link between a coil disposed within the headpiece 106 and a coil physically coupled to the artificial cochlea 108) between the headpiece 106 and the artificial cochlea 108. It can be appreciated that the communication link 114 can include a bidirectional communication link and / or one or more dedicated unidirectional communication links.

[0057] The headpiece 106 can be communicatively coupled with the sound processor 104 and can include an external antenna (e.g., a coil and / or one or more wireless communication components) configured to facilitate selective wireless coupling of the sound processor 104 with the artificial cochlea 108. The headpiece 106 can additionally or alternatively be used to selectively and wirelessly couple any other external device with the artificial cochlea 108. To this end, the headpiece 106 can be configured to be attachable to a patient's head and positioned such that the external antenna housed within the headpiece 106 is communicatively coupled with a corresponding implantable antenna (also implementable by a coil and / or one or more wireless communication components) included within or otherwise associated with the artificial cochlea 108. In this manner, stimulation parameters and / or power signals can be wirelessly transmitted between the sound processor 104 and the artificial cochlea 108 via the communication link 114 (which can include a bidirectional communication link and / or one or more dedicated unidirectional communication links that can serve a particular implementation).

[0058] The artificial cochlea 108 can include any type of implantable stimulator that can be used in conjunction with the systems and methods described herein. For example, the artificial cochlea 108 can be implemented by an implantable artificial cochlea stimulator. In some alternative embodiments, the artificial cochlea 108 can include a brainstem implant and / or any other type of artificial cochlea that can be implanted in a patient and configured to apply stimulation to one or more stimulation sites located along the patient's auditory pathway.

[0059] In some examples, the artificial cochlea 108 can be configured to generate electrical stimulation representative of audio signals processed by the sound processor 104 (e.g., audio signals detected by the microphone 102) in accordance with one or more stimulation parameters communicated to it by the sound processor 104. The artificial cochlea 108 can also be configured to apply the electrical stimulation to one or more stimulation sites (one or more intracochlear regions) in the patient's body via electrodes 112, 120 disposed along the electrode lead 110 (e.g., by applying a current through a stimulating electrode 112 that flows back through a ground electrode 120). In some examples, the artificial cochlea 108 can include a plurality of independent current sources that are respectively associated with channels defined by one or more electrodes 112. In this manner, different stimulation current levels can be applied simultaneously through multiple electrodes 112 to multiple stimulation sites.

[0060] The human cochlea is shaped like a spiral, starting at the base and ending at the apex, with auditory nerve tissue located within the cochlea. The auditory nerve tissue is organized within the cochlea in a tonotopic manner. Relatively lower frequencies are encoded at or near the apex of the cochlea (referred to as the "apex region"), while relatively higher frequencies are encoded at or near the base (referred to as the "base region"). Thus, electrical stimulation applied through electrodes disposed within the apex region (i.e., "apex electrodes") can result in the patient perceiving relatively lower frequencies, while electrical stimulation applied through electrodes disposed in the base region (i.e., "base electrodes") can result in the patient perceiving relatively higher frequencies. The division between apex and base electrodes can vary on a particular electrode lead depending on the insertion depth of the electrode lead, the patient's cochlea's anatomy, and / or any other factors, which can be helpful for particular implementations.

[0061] Figure 2 and Figure 3One example of a ring-shaped ground electrode (hereinafter "ring electrode 120") disposed on the electrode lead 110 is shown. The electrode lead 110 includes a tube 150 having a first tube portion 152 and a second tube portion 154 that are axially aligned with each other and axially abut each other, thereby forming a circumferential gap 156 that is filled with a silicone adhesive and surrounded by the ring electrode 120. The tube 150 can be formed of, for example, silicone having a durometer of about 30 to 70 Shore A. The tube 150 has an interior cavity 158 that is backfilled with a fast-curing silicone adhesive, such as the adhesive available from Avantor, located in Radnor, Pennsylvania, USA, under the name NuSil Technology MED2-4213.

[0062] A helically wound or coiled ground wire 160 extends from the cochlear implant 108 through the interior cavity 158 of the second tube portion 154 to the ring electrode 120, which is electrically connected to the ground wire 160, typically via laser welding. As shown in Figure 2 The end portion 162 of the ground wire 160 extends through the gap 156 to the ring electrode 120, thus forming an opening in the tube 150. In one example, the ground wire 160 can be coated with PPSU and can be made of Pt. This provides good bonding between the ground wire 160 and the silicone backfill in the interior cavity 158 of the tube 150. Backfilling with a silicone adhesive, such as the adhesive available from Avantor, located in Radnor, Pennsylvania, USA, under the name NuSil Technology MED2-4213, in the interior cavity 158 can provide good bonding with the PPSU-coated ground wire 160 and the wall of the tube 150. In some embodiments, the ground wire can be solid; alternatively, the ground wire can also be multi-stranded.

[0063] The preferred materials for the covering of the ground wire 160 and the backfill of the tube 150 provide good fluid resistance and increased adhesion.

[0064] As shown in Figure 2 and Figure 3 A plurality of electrode wires 176 extend through the backfilled interior cavity 158 of the tube 150 in a helically wound / coiled configuration, with each of the electrode wires 176 respectively connecting one of the stimulating electrodes 112 to the cochlear implant 108. As shown in Figure 2 and Figure 3As shown, the grounding wire 160 is wound radially relative to the electrode wires 176. Typically, the diameter of the grounding wire 160 is larger than the diameter of each of the electrode wires 176, enabling it to carry the sum of the stimulation currents generated by the electrodes 112. The grounding wire 160 may be multi-stranded to reduce stiffness caused by its larger diameter.

[0065] The annular electrode 120 includes a first end 122, a central portion 124 axially adjacent to the first end 122, and a second end 126 axially adjacent to the central portion 124. The outer surface 128 of the central portion 124 is radially raised relative to the outer surface 130 of the first end 122 and the outer surface 132 of the second end 126, to form a step 134 at the boundary between the first end 122 and the central portion 124, and a step 136 at the boundary between the second end 126 and the central portion 124, respectively. The outer surface 128 of the central portion 124 can be highly polished to obtain optimal biofilm impedance, or its surface area can be increased using laser texturing.

[0066] exist Figures 2 to 4 In the example shown, the outer diameter of the central portion 124 of the annular electrode 120 is approximately constant axially over its entire length, thus the outer surface 128 of the central portion 124 is approximately cylindrical. Furthermore, the outer diameters of the first end 122 and the second end 126 are approximately constant over their respective lengths, therefore, with substantially the same outer diameters, the outer surfaces 130 and 132 of the first end 122 and the second end 126 are approximately cylindrical. Additionally, the annular electrode 120 can be symmetrical axially, i.e., the axial dimension of the first end 122 is approximately the same as the axial dimension of the second end. Moreover, the first end 122, the second end 126, and the central portion 124 can have the same inner diameter, thus the inner surface 138 of the annular electrode 120 is cylindrical.

[0067] The ring electrode 120 can be made of Pt, Ti, PtIr alloy or Ti alloy or any other biocompatible conductor.

[0068] like Figure 4 As shown, at least a portion of the inner surface 138 of the annular electrode is provided with a silicone adhesive cover layer 140, such as a cover layer called NuSil Technology MED2-4213 available from Avantor Corporation in Radno, Pennsylvania, USA. This cover layer 140 is located between the outer surface 159 of the tube 150 and the inner surface 138 of the annular electrode 120 in order to attach the annular electrode 120 to the tube 150.

[0069] like Figures 2 to 4As shown, the first end 122 and the second end 126 of the ring electrode 120 are covered on their respective outer surfaces 130, 132 by a silicone covering layer (also denoted as "shrink") 170, 172 that extends from the outer surface 159 of the tube 150 to the step 134, 136 between the central portion 124 and the respective first end 122 or second end 126. The silicone covering layer 170, 172 serves to stabilize the attachment of the ring electrode 120 to the tube 150 and to seal the edges 142, 144 of the first and second ends 122, 126 from the tube 150 to prevent liquid from entering the space between the inner surface 138 of the ring electrode 120 and the outer surface 159 of the tube 150. The silicone covering layer 170, 172 can be made of, for example, NuSil Technology MED3-4213, similar to the attachment layer 140 between the tube 150 and the inner surface 138 of the ring electrode 120. In some examples, the ring electrode 120 can be made of Ti, with a primer compound to facilitate the adhesion of the silicone material to the Ti surface of the ring electrode 120.

[0070] As shown in the example illustrated in Figures 2 to 4 , the silicone covering layer 170 or 172 is applied such that the outer surface of each of the silicone covering layers 170, 172 is generally flush in the radial direction with the outer surface 128 of the central portion 124 of the ring electrode 120. In particular, the silicone covering layer 170, 172 terminates at the step 134, 136, respectively, such that the entire outer surface 128 of the central portion 124 of the ring electrode 120 remains exposed for contact with tissue when implanted. Thus, the manufacturing process results in a reproducible and well-defined exposed surface area of the ring electrode 120. In particular, the step 134, 136 prevents inconsistencies in the silicone application when producing the silicone covering layer 170, 172.

[0071] As shown in the example illustrated in Figures 5A to 5J , the first end 122 and / or the second end 126 can be provided with features for attaching the ground lead 160 to the ring electrode 120 and / or features for improving the adhesion of the silicone covering layer 170, 172 at the first end 122 and the second end 126. Alternatively, the central portion 124 can be provided with features for attaching the ground lead 160.

[0072] In some embodiments, the ring electrode 120 comprises at least one opening for receiving an end portion 162 of the ground lead 160 that is to be welded to the ground electrode 120. For example, as shown in Figures 5A to 5H and Figure 5J , the at least one opening can comprise at least one slot for receiving the end portion 162 of the ground lead 160. As shown in Figures 5A to 5D , at least one slot 180 can be provided on the edge 142 of the second end 126. For example, as shown inFigures 5A to 5D As shown, two slots 180 can be provided on the edge 142, which are spaced 180 degrees in the circumferential direction so that the two slots 180 are opposite to each other. As shown in Figure 2 As shown in the middle, the tip of the end 162 of the ground wire 160 can be inserted into one of the two slots 180 so that the ground wire 160 is welded to the ring electrode 120, for example by laser welding.

[0073] In the examples shown, the central portion 124 of the ring electrode 120 can be provided with at least one slot 182 for receiving the tip of the ground wire 160 so that the ground wire 160 is welded to the ring electrode 120. In addition, in these examples, two slots 182 spaced 180 degrees in the circumferential direction can be provided (only one of the slots 182 is visible in the figures). Figures 5E to 5H Figure 5J In the examples shown, the central portion 124 of the ring electrode 120 can be provided with at least one slot 182 for receiving the tip of the ground wire 160 so that the ground wire 160 is welded to the ring electrode 120. In addition, in these examples, two slots 182 spaced 180 degrees in the circumferential direction can be provided (only one of the slots 182 is visible in the figures).

[0074] Figures 5C to 5J Various features for reinforcing the attachment of the silicone cover layer 170 or 172 to the ring electrode 120 are shown in the middle.

[0075] For example, the first end portion 122 and / or the second end portion 126 of the ring electrode 120 can comprise at least one opening for injecting silicone during the manufacturing process in order to fix the silicone cover layer 170, 172 to the respective first end portion 122 or second end portion 126. For example, as shown in Figure 5H The first end portion 122 and the second end portion 126 can be provided with a plurality of holes, in particular circular holes 190, spaced apart in the circumferential direction. Alternatively, as shown in Figure 5I The edges 142, 144 of the first end portion 122 and the second end portion 126 can be provided with circumferentially spaced slots 192.

[0076] In other examples, the outer surfaces 130, 132 of the first end portion 122 and the second end portion 126 are provided with a surface structure for improving the adhesion of the silicone cover layer 170, 172. For example, as shown in Figures 5C to 5E Circumferential ribs 194 forming partial threads (see Figure 5C and Figure 5E ) or circumferential channels 196 can be provided on the outer surfaces 130, 132 of the first end portion 122 and the second end portion 126.

[0077] Alternatively or additionally, the outer surfaces 130, 132 of the first end portion 122 and the second end portion 126 can be roughened, for example by sandblasting, laser treatment or chemical etching, for improving the adhesion of the silicone cover layer 170, 172; this is schematically shown in Figures 5G to 5J

[0078] ​​In some examples, the steps 134, 136 between the first and second end portions 122, 126 and the central portion 124 can be provided with recesses 198, which are circumferentially spaced apart and are provided in the outer surface 128 of the central portion 124 and axially extend into the raised portion of the central portion 124. The recesses 198 are configured to allow injection of silicone during the manufacturing process in order to anchor the silicone cover layers 170, 172 in the respective first or second end portion 122, 126 at the steps 134, 136 (see Figure 5J ).

[0079] An example of a manufacturing method of the electrode lead 100 shown in Figures 6A to 6F is shown in Figures 2 to 4 .

[0080] In a first step shown in Figure 6A , an annular electrode 120 is provided and one end of a ground wire 160 is electrically connected with the annular electrode 120, for example at a slot 180, preferably using a laser welding process (in a method shown in Figures 6A to 6F , the annular electrode 120 is of the type shown in Figure 5A ).

[0081] In the example shown in Figure 6A , the welding slot 180 is provided in the first end portion 122 of the annular electrode 120 and the ground wire 160 extends through the inner cavity of the annular electrode 120 from the second end portion 126.

[0082] In a step shown in Figure 6B , the sub-assembly formed by the annular electrode 120 and the ground wire 160 welded thereto is mated with one end 152A of the first tube portion 152, wherein first a layer 140 of silicone adhesive, for example NuSil Technology MED3-4213, is applied on the inner surface 138 of the annular electrode 120, the first end portion 122 of the annular electrode is slid over the outer surface 159 of the one end 152A of the first tube portion 152 in order to connect the annular electrode 120 to the first tube portion 152. Thus, the end portion 162 of the ground wire 160 is clamped between the outer surface 159 of the first tube portion 152 and the inner surface 138 of the annular electrode 120, as shown in Figure 4 . After the step shown in Figures 2 to 4 , the one end 152A of the first tube portion 152 protrudes into the annular electrode 120 along a portion of the axial length of the annular electrode 120. Figure 6B

[0083] In a next step, a plurality of parallel stimulating electrode wires 176 are helically wound / coiled around a mandrel 200. As shown in Figure 6C ​As shown, the mandrel 200 with the stimulating electrode lead 176 is inserted into the interior of the ring electrode 120 and into the interior cavity 158 of the first tube portion 152. Thereafter, the ground lead 160 is radially wound on the mandrel 200 with the electrode lead 176.

[0084] In the next step, as shown, Figure 6E the second tube portion 154 is slid over the mandrel 200 with the stimulating electrode lead 176 and the ground lead 160, one end 154A of the second tube portion 154 being inserted into the interior of the ring electrode 120 such that the one end 154A of the second tube portion 154 abuts the one end 152A of the first tube portion, thereby forming the circumferential gap 156 through which the end portion 162 of the ground lead is directed towards the inner surface 138 of the ring electrode 120. In this step, the ring electrode 120 is attached to the second tube portion 154 via the silicone adhesive applied on the inner surface 138 of the ground electrode, thereby forming the adhesive layer 140. In Figure 7 the double tube concept is also shown, wherein the first tube portion 152 and the second tube portion 154 are shown sliding over each other on the mandrel 200 to meet in the interior of the ring electrode 120 by the arrows.

[0085] In Figure 6F the step shown, a silicone cover layer 170, 172 is applied on the outer surfaces 130, 132 of the end portions 122, 126 and on the outer surfaces 159 of the first tube portion 152 and the second tube portion 154 in the region adjacent to the ring electrode 120 in order to seal the ring electrode 120 to the first tube portion 152 and the second tube portion 154. The silicone cover layer 170, 172 is applied in such a way that the outer surface of the silicone cover layer 170, 172 is flush with the outer surface 128 of the central portion 124 of the ring electrode 120.

[0086] In some embodiments, the ratio of the outer surface area of the central portion 124 to the total outer surface area of the ring electrode 120 (formed by the sum of the outer surfaces of the central portion 124 and the first end portion 122 and the second end portion 126) is 0.50 to 0.75. The outer surface of the central portion 124 represents the exposed surface of the ring electrode 120.

[0087] In Figure 8The image shows a side view of an example cochlear implant 108 connected to an electrode lead 110 having a ring electrode 120. The axial distance d between one end 109 of the shell / outer shell 111 of the cochlear implant 108 (from which the electrode lead 108 extends) and a central cross-sectional plane 121 extending through the center of the axial length of the ring electrode 120 (this plane 121 represents the axial center of the ring electrode 120) can be between 8.8 and 14.8 mm to optimize the implantation procedure of the cochlear implant system and achieve optimal electrical performance.

[0088] While in the above example of the annular electrode 120, the central portion 124 is raised to ensure proper placement of the silicone coating on the annular electrode 120 by providing a boundary for silicone application to the ends of the annular electrode, in an alternative embodiment, this boundary can also be provided by annular marking structures on each end of the annular electrode. The function of these annular marking structures is to mark the correct axial boundary for silicone application, thereby ensuring that the operator applies the silicone coating to the outer surfaces of the first and second ends of the grounding electrode in a manner that prevents the silicone coating from extending axially beyond the corresponding marking structures into the central portion.

[0089] Figure 9 An example of such a ring electrode 220 is shown, wherein each of the first end 222 and the second end 226 includes ring-shaped marking structures 223, 227. Figure 9 In the example, each annular marking structure 223, 227 includes parallel, axially spaced rings 223A, 223B and 227A, 227B, respectively. For example, the annular marking structures 223, 227 can be produced by engraving or laser processing the surface portions of the first end 222 and the second end 226.

Claims

1. An electrode lead for artificial implantation in a cochlear system (100), comprising: a tube (150, 152, 154) having an inner lumen (158) and an outer peripheral surface (159); a plurality of stimulating electrodes (112) disposed on a distal end portion of the electrode lead (110); a ground electrode (120) disposed on a proximal end portion of the electrode lead for providing a current return path for stimulating current generated by the plurality of stimulating electrodes, wherein the ground electrode is ring-shaped and fixed on the outer peripheral surface around the outer peripheral surface of the tube; a ground lead (160) extending within the inner lumen of the tube to the ground electrode and electrically connected to the ground electrode through an opening in the wall of the tube; wherein the ground electrode comprises a first end portion (122), a central portion (124) axially adjacent to the first end portion, and a second end portion (126) axially adjacent to the central portion, wherein an outer surface (128) of the central portion is radially elevated relative to an outer surface (130) of the first end portion and an outer surface of the second end portion (126) so as to form a step (134, 136) at a border between the first end portion and the central portion and at a border between the second end portion and the central portion, respectively.

2. The electrode lead of claim 1, wherein, An outer diameter of the central portion (124) of the ground electrode (120) is substantially constant axially over an entire length of the central portion, such that the outer surface (128) of the central portion is substantially cylindrical.

3. The electrode lead of claim 1 or 2, wherein, An outer diameter of the first end portion (122) of the ground electrode (120) is substantially constant axially over an entire length of the first end portion, and an outer diameter of the second end portion (126) of the ground electrode is substantially constant axially over an entire length of the second end portion.

4. The electrode lead of claim 1 or 2, wherein, The ground electrode (120) comprises at least one slot (180, 182) for receiving an end portion (162) of the ground lead (160) for attaching the ground lead to the ground electrode, the at least one slot (180) being disposed on an edge (142, 144) of the first end portion (122) and / or the second end portion (126) of the ground electrode (120), or the at least one slot (182) being disposed in the central portion (124) of the ground electrode.

5. The electrode lead of claim 1 or 2, wherein, The first end portion (122) and the second end portion (126) of the ground electrode (120) are each covered by a silicone covering layer (170, 172) extending from the outer peripheral surface (159) of the tube (150, 152, 154) to the step (134, 136) at a border between the central portion (124) and the respective first end portion or second end portion of the ground electrode so as to seal the ground electrode to the tube.

6. The electrode lead of claim 5, wherein, An outer surface of each silicone covering layer (170, 172) is substantially flush with the outer surface (128) of the central portion (124) of the ground electrode (120).

7. The electrode lead of claim 5, wherein, The first end portion (122) and / or the second end portion (126) of the ground electrode (120) comprises at least one opening (190, 192) for silicone injection to anchor the silicone cover layer (170, 172) to the respective first or second end portion of the ground electrode.

8. The electrode lead of claim 7, wherein, The at least one opening comprises at least one slot (192) provided on an edge (142, 144) of the first end portion (122) and / or the second end portion (126), or the at least one opening comprises at least one hole (190).

9. The electrode lead of claim 5, wherein, The outer surface (130, 132) of the first end portion (122) and / or the second end portion (126) of the ground electrode (120) is provided with a surface structure (194, 196) for improving adhesion of the silicone cover layer (170, 172).

10. The electrode lead of claim 5, wherein, The outer surface (130, 132) of the first end portion (122) and / or the second end portion (126) of the ground electrode (120) is roughened for improving adhesion of the silicone cover layer (170, 172).

11. The electrode lead of any of claims 1-2, 6-10, wherein, The tube (150) comprises a first tube portion (152, 152A) and a second tube portion (154, 154A), which are axially aligned with each other and axially abut each other, thereby forming a circumferential gap (156) between the first tube portion (152, 152A) and the second tube portion (154, 154A), which is filled with silicone and surrounded by the ground electrode (120).

12. The electrode lead of claim 11, wherein, The circumferential gap (156) forms an opening of the tube (150), through which the ground wire (160) extends to the ground electrode.

13. The electrode lead of claim 9, wherein, The surface structure (194, 196) is a circumferential rib or a circumferential channel forming a partial thread.

14. An artificial cochlea system comprising the electrode lead (110) of any one of claims 1-13 and an artificial cochlea (108), the artificial cochlea (108) being electrically connected with the electrode lead, wherein, An axial distance between one end (109) of a housing (111) of the artificial implanted cochlea (108) and a central cross-sectional plane (121) extending through a center of an axial length of the ground electrode (120) is 8.8 to 14.8 millimeters.

15. An electrode lead for an artificial implanted cochlea system (100), comprising: a tube (150, 152, 154) having an inner volume (158) and an outer peripheral surface (159); a plurality of stimulation electrodes (112) provided on a distal end portion of the electrode lead (110); a ground electrode (220) provided on a proximal end portion of the electrode lead for providing a current return path for stimulation currents generated by the plurality of stimulation electrodes, wherein the ground electrode is ring-shaped and fixed on the outer peripheral surface around the outer peripheral surface of the tube; a ground wire (160) extending within the inner volume of the tube to the ground electrode and electrically connected to the ground electrode through an opening in the wall of the tube; wherein the ground electrode includes a first end portion (222), a central portion (224) axially adjacent the first end portion, and a second end portion (226) axially adjacent the central portion, and each of the first and second end portions includes a ring-like marker structure (223, 227).

16. A method for manufacturing an electrode lead (110) for artificial implantation into a cochlear system (100), comprising: providing a ring-shaped ground electrode (120) having an inner surface (138) and an outer surface (128, 130, 132), and including a first end portion (122), a central portion (124) axially adjacent the first end portion, and a second end portion (126) axially adjacent the central portion; welding an end portion (162) of a ground wire (160) to the ground electrode; applying a silicone-based adhesive to the inner surface of the ground electrode and attaching the ground electrode over an end of a first tube portion (152) such that an end (152A) of the first tube portion extends into the interior of the ground electrode along a portion of the axial length of the ground electrode with the ground wire extending from an opposite side of the ground electrode; spiral-winding a plurality of parallel electrode wires (176) onto a mandrel (200); inserting the mandrel with the electrode wires into the ground electrode and the first tube portion; winding the ground wire onto the mandrel; sliding a second tube portion (154) over the mandrel and into the ground electrode such that an end (154A) of the second tube portion abuts the end of the first tube portion within the interior of the ground electrode; applying a silicone covering (170, 172) over the outer surfaces (130, 132) of the first and second end portions of the ground electrode and the outer surfaces (159) of the first and second tube portions in the region adjacent the ground electrode; and removing the mandrel.

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