These studies demonstrate that PEDOT can be produced as a stable electrode coating which can be sterilized and perform effectively and safely in neuroprosthetic applications. Furthermore these findings address the necessity for characterizing in vitro properties of electrodes in biologically relevant milieu which mimic the in vivo environment more closely.

Critical to the assessment of implant devices is accurate determination of safe usage limits in an in vivo environment. Laser patterning, in particular SLIP, is a superior technique for improving the performance of implant electrodes without altering the interfacial electrode chemistry through coating. Future work will require chronic in vivo assessment of these electrode patterns.

Nerve block waveforms require the passage of large amounts of electrical energy at the neural interface for extended periods of time. It is desirable that such waveforms be applied chronically, consistent with the treatment of protracted immune conditions, however current metal electrode technologies are limited in their capacity to safely deliver ongoing stable blocking waveforms. Conductive hydrogel (CH) electrode coatings have been shown to improve the performance of conventional bionic devices, which use considerably lower amounts of energy than conventional metal electrodes to replace or augment sensory neuron function. In this study the application of CH materials was explored, using both a commercially available platinum iridium (PtIr) cuff electrode array and a novel low-cost stainless steel (SS) electrode array. The CH was able to significantly increase the electrochemical performance of both array types. The SS electrode coated with the CH was shown to be stable under continuous delivery of 2 mA square pulse waveforms at 40,000 Hz for 42 days. CH coatings have been shown as a beneficial electrode material compatible with long-term delivery of high current, high energy waveforms.

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Conducting polymers (CPs) have the potential to provide superior neural interfaces to conventional metal electrodes by introducing more efficient charge transfer across the same geometric area. In this study the conducting polymer poly(ethylene dioxythiophene) (PEDOT) was coated on platinum (Pt) microelectrode arrays. The in vitro electrical characteristics were assessed during biphasic stimulation regimes applied between electrode pairs. It was demonstrated that PEDOT could reduce the potential excursion at a Pt electrode interface by an order of magnitude. The charge injection limit of PEDOT was found to be 15 x larger than Pt. Additionally, PEDOT coated electrodes were acutely implanted in the suprachoroidal space of a cat retina. It was demonstrated that PEDOT coated electrodes also had lower potential excursions in vivo and electrically evoked potentials (EEPs) could be detected within the vision cortex.