Cochlear Implant Electrode Array Layout for Twist Compensation
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Solution Overview
Problem
Conventional cochlear implant electrode arrays are susceptible to twisting during insertion, leading to misorientation of contacts relative to the modiolus, which affects sound perception and reduces battery life due to the need for higher current levels.
Innovation Solution
The method involves forming contact subassemblies with resilient material between contacts and a mold surface, orienting contacts with flat portions, and creating perimetrically offset windows to ensure accurate alignment with the modiolus despite twisting, using a die to form the array without damaging the mold.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional electrode arrays are inserted into the cochlea, then the array can be implanted, but the array twists during insertion causing contacts to misorient relative to the modiolus
Solution Approach 1:
The patent applies asymmetry by creating non-uniform spacing between contacts (perimetric offsets) to compensate for the twisting that occurs during insertion. The contacts are positioned at different angular intervals around the cochlear spiral, with greater offsets at apical contacts that experience more rotation, ensuring all contacts face the modiolus despite the twisting insertion process
Solution Approach 2:
The patent implements preliminary action by pre-calculating and pre-positioning the perimetric offsets of contacts during manufacturing, before insertion into the cochlea. The offsets are determined based on predicted twisting behavior, so the correct orientation compensation is already in place before the insertion process begins
2Use of energy by moving object
If contacts are positioned to face the modiolus, then sound perception is optimized, but higher current is required when contacts are misoriented
Solution Approach 1:
The asymmetric perimetric offset positioning ensures optimal current efficiency by maintaining proper contact-to-modiolus alignment. This reduces the current required for effective stimulation compared to uniform spacing, while simultaneously ensuring reliable sound perception through consistent orientational accuracy
3Ease of operation
If the electrode array is made flexible for insertion, then insertion is easier, but the array may twist during insertion
Solution Approach 1:
The flexible array maintains insertion ease through its compliant nature, while the asymmetric perimetric offset configuration compensates for twisting by positioning contacts at varying angular intervals. This allows the flexible array to bend and twist during insertion while still achieving proper final orientation of all contacts relative to the modiolus
Data Source
AI summary
A method including the steps of securing a plurality of contact subassemblies to a mold surface at longitudinally spaced locations within a mold with resilient material located between the contact subassemblies and the mold surface, the contact subassemblies including, prior to being placed into the mold, an electrically conductive contact having a flat portion defining lateral ends and side portions associated with the lateral ends of the flat portion and a lead wire secured to the electrically conductive contact, introducing resilient material into the mold to form an electrode array blank including a flexible body defining an exterior surface and the electrically conductive contacts below the exterior, and forming a plurality of windows in the electrode array blank that extend through the exterior surface of the flexible body to the electrically conductive contacts.