Porous Medical Implant Electrodes with Gradient Porosity
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Solution Overview
Problem
Medical device electrodes, such as cochlear implant electrodes, experience premature dissolution due to charge imbalance and higher charge levels from multipolar stimulation signals, leading to degradation and loss of function over time, especially in smaller electrode arrays.
Innovation Solution
The development of porous electrodes with a non-uniform porosity gradient, which maintains a high electrochemical surface area to geometric surface area ratio and structural strength, allowing for controlled substance release and enhanced adhesion, thereby reducing dissolution and maintaining functionality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the electrode uses a uniform dense structure, then the structural strength is sufficient, but the electrochemical surface area is limited leading to higher dissolution rates
Solution Approach 1:
The electrode employs a porous structure with controlled porosity (30-70%) to dramatically increase the electrochemical surface area while maintaining structural integrity. The porous morphology provides more active sites for electrochemical reactions, reducing current density and dissolution rates, while the pore walls maintain sufficient mechanical strength for implantation and long-term operation.
Solution Approach 2:
The electrode implements non-uniform porosity distribution where the surface region has higher porosity (40-70%) to maximize electrochemical activity and charge transfer, while the bulk region has lower porosity (20-50%) to maintain structural strength and mechanical stability. This gradient structure optimizes both electrochemical performance and mechanical properties in different spatial zones.
2Quantity of substance
If the electrode porosity is increased to enhance electrochemical performance, then the surface area increases, but the structural strength decreases
Solution Approach 1:
The electrode implements non-uniform porosity distribution where the surface region has higher porosity (40-70%) to maximize electrochemical activity and charge transfer, while the bulk region has lower porosity (20-50%) to maintain structural strength and mechanical stability. This gradient structure optimizes both electrochemical performance and mechanical properties in different spatial zones.
Solution Approach 2:
The electrode uses composite material structures combining porous and dense regions within the same electrode body. The composite architecture integrates high-surface-area porous material for electrochemical function with dense material for structural support, achieving both high electrochemical surface area and sufficient mechanical strength simultaneously.
3Volume of moving object
If the electrode is made smaller to reduce implant size, then the device is more compact, but the charge capacity decreases leading to higher charge density and accelerated dissolution
Solution Approach 1:
The electrode employs a porous structure with controlled porosity (30-70%) to dramatically increase the electrochemical surface area while maintaining structural integrity. The porous morphology provides more active sites for electrochemical reactions, reducing current density and dissolution rates, while the pore walls maintain sufficient mechanical strength for implantation and long-term operation.
Solution Approach 2:
The electrode utilizes parameter changes in porosity (from 30% to 70% across different regions) to optimize the balance between electrochemical surface area and mechanical strength. By controlling the porosity parameter, the electrode achieves high charge capacity in a compact form factor, reducing charge density and extending lifespan despite small size.
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
The porous electrodes effectively prolong the lifespan of medical devices by optimizing porosity for multiple functions, including structural integrity and electrochemical performance, while minimizing premature dissolution and ensuring consistent performance over extended periods.
Implementation Method 1
The first portion has a substantially non-uniform porosity along a direction from the surface to the second portion
Implementation Method 2
The surface region is configured to undergo dissolution over time while the porous electrode is implanted on or within the recipient with the ratio being substantially unchanged by the dissolution
Data Source
AI summary
An apparatus includes an electrode configured to be implanted on or within a recipient's body. The electrode includes a first portion having a surface configured to be in electrical communication with the recipients body and a second portion integral with the first portion and in mechanical and electrical communication with the first portion. The electrode further includes a plurality of pores extending from the surface of the first portion to the second portion such that the first portion has a substantially non-uniform porosity along a direction from the surface to the second portion.