Method for manufacturing wire array with molded contacts for cochlear implant electrode array

Abstract

FIELD: medical equipment.SUBSTANCE: method for manufacturing a wire array for a cochlear implant electrode array uses a tooling consisting of three connectable segments: the first segment for creating a ridge of wire ends, the second for forming a silicone-bonded wire array, and the third for forming annular electrode contacts into a channel shape having two through channels for filling with silicone. In the first segment of the equipment, each wire of the wire array, on which a ring is previously placed, is passed between the vertical guides, one end of each wire is fixed on an individual pin of the first segment to form a ridge. In the second segment, the wires are pulled through guides located with zero clearance, forming a dense bundle of wires, and silicone is applied. In the third segment, the ring of each wire is placed in an individual tray, the unfastened ends of the wires are fixed on individual pins and ring-shaped electrode contact blanks are placed on them, one contact for each wire, and the electrode contacts are given the shape of a channel.EFFECT: precise manufacture of an electrode array with predictable rigidity and calculated geometry along the entire length.6 cl, 11 dwg

Description

[0001] Field of technology to which the invention relates

[0002] The invention relates to the field of neurosurgical implants, namely to the production of an array of thin wires containing molded electrode contacts, and can be used in the production of an electrode array for a cochlear implant intended for the treatment of profound bilateral sensorineural deafness.

[0003] Technical level

[0004] For over 20 years, cochlear implant systems have been routinely used in clinical practice to treat profound bilateral sensorineural hearing loss. These systems consist of an external unit—a speech processor and coil—and an implantable response unit—a stimulator / receiver and electrode array. Cochlear implant systems have proven to be a reliable, proven, and the only possible method for restoring hearing in a number of clinical cases.

[0005] A cochlear implant system is a type of electronic implant designed to detect sound waves around the user and convert them into a sequence of microelectrical impulses that are transmitted to the nerve endings in the scala tympani of the cochlea, thereby producing auditory sensations. The electrode array is a structural element of the cochlear implant system, consisting of a long, thin silicone shell with an array of wires located inside, running from the stimulator to the electrode contacts. Its purpose is to stimulate the nerve endings using electrical impulses.

[0006] The electrode array is subject to numerous design requirements (external geometric dimensions, number, shape, and placement of electrodes, wire distribution, length of the active (stimulating) portion), as well as requirements related to biocompatibility, flexibility, high electrical performance, and corrosion and wear resistance. In addition to component requirements, the electrode array design must address specific challenges, particularly those related to the anatomy of the cochlea and scala tympani. The electrode array is a very miniature component, less than 1 mm thick across, and its manufacture requires the use of unique tooling.

[0007] A cochlear implant electrode is known (see patent AU2014317918B2, published on 12.01.2017), comprising: an implantable matrix holder having a central longitudinal axis and an outer surface; a plurality of electrode contacts distributed on the outer surface of the matrix holder along the longitudinal axis for delivering electrical stimulation signals to adjacent nervous tissue; and a plurality of electrode wires embedded in the matrix holder for conducting electrical stimulation signals. Each electrode wire has an end lead electrically connected to a corresponding electrode contact.Each electrode wire comprises an internal liquid-conducting material surrounded by an external seal, and the matrix holder is configured to interact with the liquid conductive material of the electrode wires when contact occurs between the matrix holder and the liquid conductive material, forming a local leakage seal configured to prevent migration of the liquid conductive material to the outer surface of the matrix holder. The outer seal of the electrode wires is made of a styrene, ethylene, butylene, and styrene (SEBS) block copolymer material.

[0008] An ear implant electrode array is known (patent US8831750B2, published 09.09.2014), comprising a plurality of electrode wires for transmitting electrical stimulation signals; an electrode stimulation contact is located at the end of each electrode wire for transmitting electrical stimulation signals to adjacent nerve tissue; an electrode holder made of an elastic material that encloses the electrode wires and has an outer surface with a plurality of contact holes that open the contacts for stimulation; and a plurality of individual bending control elements distributed along the length of the electrode array for controlling the flexibility of the electrode array during bending depending on a threshold bending radius, which should be greater for a bend smaller than the threshold bending radius, and less for a bend exceeding the bending threshold radius.The ear implant's electrode array further comprises an electrode array core enclosed in an electrode holder. The electrode array core is made of a flexible polymer material with electrode wires embedded within. The array core includes an elongated helical portion with multiple helical turns. The helical portion of the array core extends along the entire length of the electrode holder. The other portion of the array core has a flat, elongated, wavy shape with multiple repeating waves.

[0009] A cochlear implant electrode array is known (patent application WO2014179267A1, published on November 6, 2014), comprising a plurality of electrode wires for transmitting electrical stimulation signals; electrode stimulation contacts at the end of each electrode wire for delivering electrical stimulation signals to adjacent nervous tissue; an elongated electrode holder made of an elastic material enclosing the electrode wires, having a central longitudinal axis and an outer surface with a plurality of contact holes opening the contacts for stimulation; and a plurality of elastic friction-reducing rings distributed along the outer surface of the electrode holder and protruding above it, acting to limit the contact area between the electrode holder and the side wall of the scala during surgical insertion of the electrode array into the cochlea of ​​an implanted patient.

[0010] The problem solved by the proposed invention is the use of specialized equipment that makes it possible to obtain an even bundle of parallel and tightly located wires with fixed molded electrode contacts, placed at a distance between them equal to the required distance between the electrode contacts on the manufactured electrode grid.

[0011] Disclosure of the essence of the invention

[0012] The technical result of the invention consists in ensuring the precise manufacture of an electrode array with predictable rigidity and calculated geometry along the entire length of the electrode array, and, as a consequence, reducing the likelihood of injury during implantation, increasing the stability of the functioning of the cochlear implant and increasing productivity in the manufacture of cochlear implants by minimizing manual labor compared to assembling the electrode array without a pre-prepared array of wires.

[0013] The technical result consists in using specialized molding equipment to create a uniform, kink-free wire harness with fixed electrode contacts.

[0014] The essence of the invention is explained by illustrations, in which: Figure 1 is an image of a segment of the electrode array of a cochlear implant, consisting of an array of wires with electrode contacts fixed at the tips and enclosed in a silicone shell, Figure 2 is a schematic image of specialized equipment consisting of three segments, suitable for the manufacture of an array of wires with molded electrode contacts for the electrode array of a cochlear implant, Figure 3 is a schematic image of Segment No. 1 of the specialized equipment, Figure 4 is a schematic image of Segment No. 2 of the specialized equipment, Figure 5 is a schematic image of Segment No. 3 of the specialized equipment, Figure 6 is a section of an electrode contact formed by pressing, with a wire clamped inside and two cavities for filling with silicone,Figure 7 is an image of a forming punch with an electrode contact placed in a specialized tooling tray before forming, Figure 8 is an image of a forming punch with an electrode contact placed in a specialized tooling tray after forming, Figure 9 is an image of a tooling intended for creating a twisted wire, Figure 10 is an image of a part with which the wire is wound, Figure 11 is a rotating shaft with a disk with holes.

[0015] To achieve the stated objective, the method for manufacturing a wire array with molded contacts for the electrode array of a cochlear implant uses specialized equipment consisting of three connectable segments:

[0016] • Segment #1, responsible for creating a comb of ordered wire tips that can be used to create a connector between the electrode array and the receiver / stimulator.

[0017] • Segment No. 2, responsible for forming a silicone-bonded array of wires of the required length, which is the conductor of the electrode grid.

[0018] • Segment No. 3, responsible for forming the ring-shaped electrode contacts into a type of channel shape, having two through channels suitable for filling them with silicone.

[0019] The division of the equipment into separate segments is done in order to simplify the production of equipment and to quickly, without reworking the entire equipment, make changes to the design of individual parts of the created wire array.

[0020] This method involves assembling a wire array containing 14 to 24 wires, each 20 to 50 µm thick, made of platinum-iridium alloy coated with polytetrafluoroethylene (Teflon) or poly-para-xylylene (Parylene), bonded together with non-toxic biocompatible silicone. The wire array length ranges from 80 to 140 mm and corresponds to the length of the electrode array being manufactured. On one side of the wire array is a comb of orderly wire tips that can be used to create a connector between the electrode array and the stimulator / transmitter of the cochlear implant. On the other side, electrode contacts are molded onto the wire array, one per wire, which will provide stimulation of the nerve endings passing through the spiral ganglion of the cochlea. This array is suitable for placement in the silicone shell of a cochlear implant electrode array.

[0021] Furthermore, the technology can be further improved by using an additional device in segment #2 that allows for the formation of a twisted wire harness instead of a straight one. Literary sources report that, as children age, the skull size increases by 12 mm (with a standard deviation of 5 mm) as the distance from the round window to the sinusoidal angle increases. The complex twisted structure of the wires allows for the elongation that may occur during cranial growth.

[0022] A specialized tool is used to create a twisted wire. All wires are positioned in a longitudinal channel. These wires are threaded through a hole in the post. Once the wire is threaded, each end is pushed through a hole in the perforated disk. Once each wire is in the disk, the guide axis is rotated. This rotational motion twists the wires around a single axis. The resulting braided structure of the wire allows it to withstand the tensile forces that occur during implant use.

[0023] Implementation of the invention

[0024] To assemble the structure, a ring is threaded through each segment, after which the wire is passed between the vertical guides on segment 1, with one end secured to an individual pin on segment 1. The threaded ring is then placed in the individual support of segment 3, and the unsecured end of the wire is secured to an individual pin on segment 3. This process is repeated with each wire. In the support, the rings are compressed, mechanically crimping them onto the wires. The bundle of wires running along segment 2 is lubricated with silicone, creating a silicone bundle. The structure can then be pulled out of the segments. Additionally, using the device in Fig. 9, the wires can be twisted into a "pigtail." After twisting, silicone is applied to the pigtail to create a silicone bundle containing the wires in a "pigtail" shape rather than straight ones. This wire structure prevents breakage under longitudinal tension.

Claims

1. A method for manufacturing a wire array for a cochlear implant electrode array, characterized in that use a tool consisting of three connecting segments: the first segment for creating a comb of the ends of the wires, the second for forming an array of wires bonded with silicone, and the third for forming annular electrode contacts into a channel shape with two through channels for filling with silicone; in the first segment of the equipment, each wire of the wire array, on which a ring is previously placed, is threaded between the vertical guides, one end of each wire is fixed on an individual pin of the first segment to form a ridge, in the second segment, the wires are pulled through guides located with zero clearance, forming a dense bundle of wires, silicone is applied, In the third segment, the ring of each wire is placed in an individual tray, the unfastened ends of the wires are fixed on individual pins and ring-shaped electrode contact blanks are placed on them, one contact for each wire, and the electrode contacts are given the shape of a channel.

2. The method according to paragraph 1, characterized in that the supports are located at a distance equal to the distance between the electrode contacts in the electrode grid.

3. The method according to paragraph 1, characterized in that the supports are spaced apart relative to the longitudinal axis of the wires.

4. The method according to paragraph 1, characterized in that the shape of the electrode contact blanks is given by compression in the cradles using a punch until a channel shape is formed, having two through channels for filling with silicone.

5. The method according to paragraph 1, characterized in that the array of wires in the guides is covered with silicone.

6. The method according to paragraph 1, characterized in that in the second segment the wires are twisted using a device additionally installed in it for forming a bundle of twisted wires.

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