Cochlear Implant Ground Ring Electrode Assembly Against Fluid Ingress
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Solution Overview
Problem
Cochlear implant electrode leads with ground ring electrodes are susceptible to fluid ingress, leading to high electrode impedances over time, and the silicone tapers used for securing the ring electrode can be inconsistent due to variations in silicone application.
Innovation Solution
A dual tube configuration is used in the manufacturing method, where a first tube portion and a second tube portion abut each other within the ground ring electrode, allowing the ground wire to extend through the gap between them, thereby avoiding the need to pass the ground wire through the inner diameter of the tube. Additionally, the ground wire is wound co-radially with the electrode wires, and made of Pt coated with PPSU to improve bonding and manufacturability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the ground wire is passed through the inner diameter of the tube and pulled out through an opening cut in the tube wall, then the ground electrode can be assembled, but the device becomes susceptible to fluid ingress and manufacturing consistency deteriorates
Solution Approach 1:
The single tube is divided into two separate tube portions (first tube portion and second tube portion) that abut each other within the ground ring electrode. The ground wire extends through the gap between these two tube portions rather than through a single tube wall, eliminating the need to cut openings in the tube and preventing fluid ingress paths.
Solution Approach 2:
Instead of passing the ground wire through the tube from the inside and pulling it out through the wall (conventional approach), the invention inverts the approach by having the ground wire extend through the gap between two abutting tube portions from the outside, eliminating the penetration opening that would allow fluid ingress.
2Strength
If silicone tapers are applied at both sides of the ring electrode, then the ring electrode can be secured in place, but manufacturing consistency deteriorates due to lack of consistent boundary
Solution Approach 1:
The first tube portion and second tube portion are pre-assembled in an abutting configuration within the ground ring electrode before silicone taper application. This preliminary assembly establishes consistent boundaries (the abutting surfaces of the two tube portions) that guide uniform silicone application, ensuring consistent manufacturing results.
Solution Approach 2:
The abutting interface between the first tube portion and second tube portion acts as an intermediary structure that provides a consistent boundary for silicone taper application. This intermediate abutting configuration ensures uniform silicone distribution and consistent securing of the ring electrode.
3Strength
If the ground wire is made of Pt and coated with PPSU, then bonding to ground wire and silicone backfill is improved, but manufacturing complexity increases
Solution Approach 1:
The ground wire is constructed as a composite material structure with a Pt core and PPSU coating. This composite construction provides both the electrical conductivity of Pt and the bonding properties of PPSU to silicone backfill, improving overall performance while the standardized composite structure simplifies manufacturing through consistent material properties.
Data Source
Figure 1
Figure 2~3
Figure 4~5B
AI summary
There is provided an electrode lead for a cochlear implant system, comprising a tube (150, 152, 154) having an interior volume (158) and an outer peripheral surface (159); a plurality of stimulating electrodes (112) disposed on a distal portion of the electrode lead (110); a ground electrode (120) disposed on a proximal portion of the electrode lead for providing a current return path for stimulation current generated by the plurality of stimulation electrodes, wherein the ground electrode is ring-shaped and is fixed on and around the outer peripheral surface of the tube; and a ground wire (160) extending within the interior volume of the tube to the ground electrode and being electrically connected to the ground electrode through an opening (156) in a wall of the tube. 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 the outer surface (128) of the central portion is radially elevated relative to the outer surface (130) of the first end portion and the outer surface of the second end portion (134), so as to form a step (134, 136) at the boundary between the first end portion and the central portion and at the boundary between the second end portion and the central portion, respectively.