A program is proposed for the research and development of new percutaneous electrode designs suitable for chronic intramuscular stimulation. The proposed designs offer innovation in two important areas: the structural component of the flexible lead and the charge injection material. The first innovation is the use of Ti, Ti-6A1-4V-ELI, and Ta wire as the structural components of the flexible lead. These materials have the potential to provide a combination of mechanical strength, fatigue resistance, corrosion resistance, and electrical conductivity superior to 316LVM stainless steel or any other alloys heretofore used as electrode leads. The second innovation is in the charge injection material. Two materials are proposed: Ir oxide thermally deposited onto Ti or Ti alloy wire, and TA205 anodically formed on Ta wire. Both Ir oxide and TA205 permit reversible and corrosion-free charge injection at higher charge densities than is available with 316LVM stainless steel. During Phase I of the research program we propose to evaluate the suitability of Ti, TI-6A1-4V-ELI, and Ta as flexible lead materials for chronic percutaneous electrode applications. The results of the evaluation will provide a basis for further development of high charge capacity intramuscular electrodes which may have substantially improved lifetimes during chronic use.
