This study explored the feasibility of applying nanocomposites derived from conducting organic polymers and silicone elastomers to fabricate electrodes for neural stimulation. A novel combination of nanoparticulate polypyrrole polymerized within a processable elastomeric silicone host polymer was evaluated in vitro and in vivo. The electrical properties of the elastomeric conductors were strongly dependent on their composition, and mixtures were identified that provided high and stable conductivity. Methods were developed for incorporating conductive polymer-siloxane co-polymer nanocomposite and silicone insulating polymers into thin-layered structures for simple single-poled electrode fabrication. In vitro testing revealed that the materials were stable under continuous pulsing for at least 10 days. Single contact prototype nerve cuff electrodes were fabricated and device functionality was demonstrated in vivo following acute implantation. The results of this study demonstrate the feasibility of conductive elastomers for peripheral nerve stimulating electrodes. Matching the mechanical properties of cuff electrode to those of the underlying neural tissue is expected to improve the long-term tissue response to the presence of the electrode.

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This research effort sought to demonstrate that combining select phosphonic acid additives with Nafion could improve Nafion's high temperature electrochemical performance. A 1:1 mixture of the additive with Nafion, resulted in a film that demonstrated 30% higher conductivity than a phosphoric acid equilibrated Nafion control at 175°C. This improvement to the high temperature conductivity of the proton exchange membrane Nafion is without precedent. In addition, thermal analysis data of the test films suggested that the additives did not compromise the thermal stability of Nafion. The results suggest that the improved Nafion proton exchange membranes could offer superior electrochemical performance, but would retain the same degree of thermal stability as Nafion. This research could eventually lead to portable fuel cells that could oxidize unrefined hydrocarbon fuels, resulting in wider proliferation of fuel cells for portable power.

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