Flexible Spinal Cord Electrode Arrays with Bonded Polymer Substrates
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Solution Overview
Problem
Current electrode arrays for spinal cord stimulation lack mechanical flexibility and durability, leading to separation from the polymer substrate over time, which limits their ability to deliver consistent electrical stimulation for extended periods.
Innovation Solution
Development of flexible electrode arrays with electrodes bonded to a polymer substrate, using materials like polyimide and parylene, and metals such as platinum and titanium, designed to maintain electrical connectivity and mechanical stability for prolonged use, featuring a roughened surface for enhanced charge transfer and channel isolation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional electrode arrays are used for spinal cord stimulation, then electrical stimulation can be delivered, but the electrodes separate from the polymer substrate over time, reducing reliability
Solution Approach 1:
The patent employs a composite structure consisting of a polymer substrate (e.g., polyimide or parylene) combined with metal electrode layers (e.g., platinum, titanium, or gold). This composite material approach creates a durable, integrated electrode array that maintains structural integrity and electrical functionality over extended in vivo periods, directly addressing the reliability and duration contradiction.
2Adaptability or versatility
If rigid electrode arrays are used, then structural stability is maintained, but mechanical flexibility is reduced, limiting adaptability to spinal cord movements
Solution Approach 1:
The patent utilizes flexible polymer substrates such as polyimide or parylene with controlled thickness (e.g., 12.5 µm to 100 µm) to create an electrode array that can bend and conform to the spinal cord surface. This flexible film structure maintains structural stability while enabling mechanical adaptability to spinal cord movements and implantation site variations.
3Reliability
If smooth electrode surfaces are used, then manufacturing is simpler, but charge transfer capability is reduced, lowering electrical performance
Solution Approach 1:
The patent applies localized surface roughening (e.g., via electrochemical etching, sandblasting, or chemical treatment) to specific electrode contact areas rather than the entire surface. This creates micro-scale rough features that increase surface area and improve charge transfer capability at the electrode-tissue interface, while maintaining smooth surfaces elsewhere for ease of manufacturing and integration.
Data Source
AI summary
In certain embodiments an electrode array for epidural stimulation of the spinal cord is provided where the array comprises a plurality of electrodes disposed on a flexible polymer substrate; said electrodes being electrically connected to one or more lead wires and/or connection points on an electrical connector; where the electrodes of said array are bonded to said polymer so that the electrodes can carry an electrical stimulation signal having a voltage, frequency, and current sufficient to provide epidural stimulation of a spinal cord and/or brain in vivo or in a physiological saline solution, without separation of all or a part of an electrode from the polymer substrate.