Asymmetric Cochlear Implant Electrodes for Impedance Reduction
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Solution Overview
Problem
Neurostimulating devices face challenges in efficiently delivering electrical stimulation due to high impedance at the electrode-tissue interface, which limits the effectiveness of the stimulation and reduces battery life.
Innovation Solution
The use of electrodes with longer edge lengths and asymmetric designs, which increase the edge length-to-surface area ratio, reduces impedance and focuses electrical stimulation on target tissues while minimizing it in non-target areas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional electrodes with shorter edge lengths are used, then the device complexity is reduced and manufacturing is easier, but the impedance at the electrode-tissue interface is high which reduces stimulation efficiency and battery life
Solution Approach 1:
The patent applies asymmetry by designing electrodes with non-uniform edge lengths, where at least one edge has a significantly longer length than the others. This asymmetric geometry increases the edge length-to-surface area ratio, which reduces the impedance at the electrode-tissue interface and improves stimulation efficiency without requiring complex multi-component structures
Solution Approach 2:
The patent changes the geometric parameters of the electrode by increasing the edge length while maintaining or reducing the surface area. This parameter change (increasing edge length-to-surface area ratio) directly reduces impedance and improves battery life, resolving the contradiction between stimulation efficiency and device complexity
2Duration of action of stationary object
If electrodes with longer edge lengths are used, then the impedance is reduced and battery life is extended, but the electrode design becomes more complex and manufacturing difficulty increases
Solution Approach 1:
The asymmetric electrode design with longer edges maintains manufacturability by using simple geometric modifications rather than complex structures. The longer edges can be achieved through conventional fabrication methods by adjusting the dimensions of the electrode contacts, making the design easy to manufacture while extending battery life through reduced impedance
3Manufacturing precision
If symmetric electrode designs are used, then the manufacturing precision requirements are lower and production is simpler, but the electrical stimulation cannot be optimally focused on target tissues
Solution Approach 1:
The asymmetric electrode design provides adaptability for targeted tissue stimulation by creating non-uniform current distribution patterns. The longer edges can be positioned to target specific anatomical regions, allowing precise control over stimulation location without requiring extremely tight manufacturing tolerances on all dimensions
Solution Approach 2:
The patent applies local quality by creating electrodes with different edge lengths at different locations, which produces localized current density variations. This allows the electrode to focus stimulation on specific target tissues while the manufacturing process only requires reasonable precision on the critical edge dimensions that create the asymmetric current distribution
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 approach enhances the efficiency of electrical stimulation delivery and extends battery life by reducing impedance and allowing for more targeted tissue stimulation.
Implementation Method 1
The electrical impedance of the implantable lead is related to a number of parameters, including the impedance of the interface of the electrodes with the biological tissue. Reducing the impedance of the implantable lead can be desirable for a number of reasons, including more efficient delivery of electrical stimulation and longer battery life.
Data Source
AI summary
An implantable lead may include an insulating substrate and a first asymmetric electrode formed on the insulating substrate. The first asymmetric electrode may have external perimeter edges defining a boundary between an exposed portion of the first electrode and the insulating substrate, wherein the external perimeter edges of the first electrode have asymmetric edge lengths.