Variable Shape Cochlear Implant Electrode Wiring
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Solution Overview
Problem
Cochlear implant electrodes face challenges in balancing mechanical robustness, flexibility, and size constraints, particularly in accommodating complex insertion paths and biological compatibility, as increased channel numbers lead to rigidity and adverse tissue reactions.
Innovation Solution
The design incorporates electrode wires with varying shapes along the electrode lead and array, including impact reinforcement elements made of polymer or metallic materials, to provide region-specific mechanical properties for micro-movement resistance, flexibility, and impact resistance, while maintaining a compact size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the number of electrode stimulation channels is increased, then the number of metallic wires increases to provide more stimulation capability, but the implant electrode becomes increasingly rigid which complicates insertion and causes tissue damage
Solution Approach 1:
The electrode wire is divided into multiple segments with different cross-sectional shapes along its length. Each segment can have a different shape (e.g., circular, elliptical, triangular) to provide varying mechanical properties. This segmentation allows the electrode to have high strength in some regions while maintaining flexibility in others, resolving the contradiction between needing multiple wires for high channel count and maintaining flexibility for easy insertion.
Solution Approach 2:
Different portions of the electrode wire are given different local qualities through varying cross-sectional shapes. For example, the proximal portion may have a circular cross-section for strength, while the distal portion has an elliptical or triangular cross-section for flexibility and conformability to the cochlear structure. This local differentiation allows the single electrode to satisfy multiple mechanical requirements simultaneously.
2Stability of the object's composition
If electrode structures are made highly resistant to micro-movements, then stability is improved, but the electrode occupies relatively more space which is problematic in the confined cochlear environment
Solution Approach 1:
The electrode implements local quality by providing different cross-sectional shapes at different locations. The proximal portion (closer to the implantable pulse generator) has a circular cross-section that provides high resistance to micro-movements and mechanical stress. The distal portion (entering the cochlea) has an elliptical or triangular cross-section that reduces the occupied space and allows better conformability to the cochlear scala. This spatial differentiation of mechanical properties resolves the contradiction between stability and compactness.
3Volume of moving object
If electrode structures are made small in size to fit the cochlea, then space utilization is improved, but the electrode becomes relatively rigid which complicates navigation through tortuous insertion paths
Solution Approach 1:
The electrode is segmented into proximal and distal portions with different cross-sectional geometries. The proximal portion has a larger circular cross-section that provides structural integrity and resistance to bending during insertion. The distal portion has a smaller elliptical or triangular cross-section that is more flexible and can navigate the tortuous path of the cochlear insertion tract. This segmentation allows the electrode to be both structurally sound and easily insertable.
Solution Approach 2:
The electrode's mechanical properties are made dynamic along its length rather than uniform. The transition from circular to elliptical/triangular cross-section creates a gradient of flexibility, with the distal end being more compliant to accommodate the complex insertion path while the proximal end remains rigid for stability. This dynamic variation in mechanical properties throughout the electrode structure resolves the contradiction between size and flexibility.
4Ease of manufacture
If the electrode lead has uniform mechanical properties throughout, then manufacturing is simplified, but it cannot accommodate the different mechanical requirements of various portions (e.g., impact resistance at skull vs. flexibility in cochlea)
Solution Approach 1:
The electrode lead is manufactured as a segmented structure with distinct sections having different cross-sectional shapes. The proximal section has a circular cross-section for impact resistance and structural stability, while the distal section has an elliptical or triangular cross-section for flexibility and cochlear conformability. This segmentation allows each portion to be optimized for its specific functional requirements while still being part of a single integrated electrode structure.
Solution Approach 2:
The electrode implements local quality by varying the cross-sectional geometry at different locations along its length. This creates region-specific mechanical properties where the proximal portion provides impact resistance and structural support, while the distal portion provides flexibility and adaptability to the cochlear environment. This local differentiation resolves the contradiction between manufacturing simplicity and functional adaptability.
Data Source
Figure 1~2
Figure 3~4
Figure 5A~5B
AI summary
A cochlear implant electrode is described. A basal electrode lead carries electrical stimulation signals from an implant housing to a cochleostomy opening, and a portion of the electrode lead has a periodically recurring lead shape. An apical electrode array at the cochleostomy end of the electrode lead passes into a cochlea scala and includes electrode contacts for applying the electrical stimulation signals to target neural tissue. A portion of the electrode array has a periodically recurring array shape different from the lead shape.