Electrode Wall Height Tuning for Uniform Current Density
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Solution Overview
Problem
Existing electrode manufacturing methods fail to achieve a uniform current density profile, leading to potential brain tissue damage and electrode corrosion, and are not scalable for mass production, particularly in deep brain stimulation applications.
Innovation Solution
A method for manufacturing electrodes involves simulating and adjusting the height of a dielectric wall surrounding a conductive element to ensure maximum current density remains below a predefined threshold, using CMOS-compatible processes, allowing for the production of electrodes with a flatter current density profile and safer brain stimulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a planar electrode is used, then the manufacturing is simple, but the current density is uneven and higher around the perimeter
Solution Approach 1:
The patent transitions from a two-dimensional planar electrode to a three-dimensional structure by adding a hemispherical protrusion on the electrode surface. This dimensional change redistributes the current density across the curved surface, reducing the perimeter effect and achieving more uniform current density while maintaining manufacturing feasibility through standard semiconductor fabrication processes.
2Power
If the stimulation current intensity is increased, then the electrode can fulfil its function, but brain tissue damage and electrode corrosion occur
Solution Approach 1:
The patent modifies the geometric parameters of the electrode surface by adding a hemispherical protrusion with a specific radius. This geometric parameter change alters the current density distribution, allowing the electrode to deliver sufficient total current while keeping the local current density below tissue damage thresholds, thus enabling higher safe injected charge.
3Manufacturing precision
If a perfect sphere or half sphere electrode shape is used, then the current density profile is flat, but the fabrication is impractical and not scalable
Solution Approach 1:
The patent segments the electrode fabrication process into standard CMOS-compatible steps: forming a hemispherical photoresist pattern, depositing conductive material conformally, and planarizing. This segmentation allows the complex three-dimensional shape to be manufactured using conventional planar semiconductor processing techniques, making the solution scalable to mass production.
Data Source
AI summary
A method includes providing a first electrically conductive element over a top surface of a substrate. The method includes measuring at least one parameter indicative of the shape or dimensions of the first electrically conductive element. The method includes simulating the first electrically conductive element and a dielectric wall surrounding the first electrically conductive element for a plurality of wall heights by using the at least one parameter as an input. The method includes for each wall height, computing the maximum current density present at a surface of the first electrically conductive element. The method includes determining, from the maximum current densities, wall height(s) for which the maximum current density is below a threshold. Furthermore, the method includes providing a second electrically conductive element, identical to the first electrically conductive element, surrounded by a wall having a wall height of the determined wall height(s).