Cochlear Implant Electrode With Liquid Metal Alloy Seal
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Solution Overview
Problem
Cochlear implant electrode arrays face mechanical failures due to external forces causing wire breakage and hydrogel separation from electrode surfaces, leading to open circuits and fibrous tissue formation, which existing technologies have not adequately addressed.
Innovation Solution
The use of electrode wires made from a sealed non-crystal conductive liquid metal alloy, such as eutectic gallium indium, embedded within a flexible array carrier with a reactive outer seal and additional leakage barriers, including hydrogel contact covers, to absorb external forces and prevent migration of the conductive material upon breakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional solid metal electrode wires are used, then electrical conductivity is maintained, but mechanical fatigue and wire breakage occur due to external forces
Solution Approach 1:
The patent changes the physical state of the conductive material from solid crystal structure to liquid state. The liquid metal alloy maintains electrical conductivity while eliminating mechanical fatigue and wire breakage caused by external forces, as liquid materials can deform and absorb mechanical stress without structural failure.
Solution Approach 2:
The patent creates a composite structure with liquid metal alloy conductive material enclosed within a flexible polymer seal. This composite design combines the electrical conductivity of metal with the mechanical flexibility and fatigue resistance of polymer materials, solving both conductivity and durability requirements.
2Reliability
If liquid metal alloy is used as conductive material, then mechanical fatigue is eliminated, but leakage of conductive material may occur upon seal breakage
Solution Approach 1:
The patent applies preliminary protective measures by designing a reactive flexible polymer material that automatically forms a seal at the site of any breakage. This preliminary anti-action prevents the harmful migration of liquid metal alloy before it can cause damage, by having the protective mechanism ready to activate immediately upon seal failure.
Solution Approach 2:
The flexible polymer material possesses self-healing capability through its reactive properties. When the outer seal breaks, the polymer automatically reacts with the liquid metal alloy to form a new seal, enabling the system to self-repair and prevent leakage without external intervention.
3Reliability
If hydrogel material is applied over electrode contacts, then biocompatibility and charge transfer are improved, but hydrogel separation from electrode surface occurs due to swelling
Solution Approach 1:
The patent segments the protective covering into distinct functional layers: an inner flexible polymer seal that maintains intimate contact with the electrode wire, and an outer hydrogel layer that provides biocompatibility. This segmentation allows each layer to perform its specific function without the swelling-induced separation problems affecting the electrode connection.
Solution Approach 2:
The flexible polymer seal acts as an intermediary between the liquid metal alloy electrode wire and the hydrogel material. It provides a stable, non-swelling interface that maintains electrical contact while allowing the hydrogel to perform its biocompatible function without direct attachment to the electrode, thus avoiding swelling-induced separation.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution enhances the flexibility and atraumaticity of the electrode array, preventing mechanical fatigue and migration of the conductive material, thus reducing the occurrence of open circuits and fibrous tissue formation, while maintaining effective electrical stimulation.
Implementation Method 1
The flexible material of the array carrier is configured to be reactive with the non-crystal conductive material of the electrode wires so that if a break occurs in the outer seal of an electrode wire that allows contact between the flexible material and the non-crystal conductive material, then a local leakage seal will form at the break
Implementation Method 2
External forces to the implant electrode then can be directly absorbed by the electrode wires via deformation that is at least partially reversible without any mechanical fatigue of the wire structure
Implementation Method 3
The hydrogel materials swells when it contacts the perilymph fluid within the cochlea, absorbing more than its own dry weight
Data Source
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AI summary
A cochlear implant electrode includes an implantable array carrier made of flexible material with electrode contacts distributed on its outer surface along a longitudinal axis. Electrode wires are embedded within the array carrier, each electrode wire having a terminal end electrically connected to a corresponding electrode contact for applying electrical stimulation signals carried by the electrode wires to adjacent neural tissue within the cochlea. Each electrode wire has an inner non-crystal conductive material surrounded by a flexible outer seal. The flexible material of the array carrier is configured to be reactive with the non-crystal conductive material of the electrode wires so that if a break occurs in the outer seal of an electrode wire that allows contact between the flexible material and the non-crystal conductive material, then a local leakage seal will form at the break that resists migration of the non-crystal conductive material to the outer surface of the array carrier.