Natalie Page1, Gregory Taylor1, John Lucchi1,4, Rhandy Paladines1, Anthony Marti1, *Jeffrey Hettinger1, Saxon Tint2, Shahram Amini2,5, Andy Fones3, Hugh Hamilton3
1Rowan University, Glassboro, NJ; 2Johnson Matthey Inc., West Chester, PA; 3Johnson Matthey Inc., Reading, United Kingdom; 4Currently at University of Central Florida; rCurrently at Pulse Technologies, Quakerstown, PA
Implantable electrode miniaturization reduces patient trauma, improves device performance, allows the isolation of specific neurons and increases device longevity due to the reduction in induced scar tissue. Improvements to the charge coupling between the conducting electrodes with coating and the biological environment allow smaller electrodes to be developed. The coatings need to be biocompatible. They should also increase the effective surface area, the reversible oxidation/reduction of the coating material for enhanced recording/stimulating, or both. Previous works have focused on the activation of IrO2, variation of microstructure of the coatings at various deposition pressures and the behavior of these coatings in a simulated biological environment. These reports confirm the excellent performance of IrO2 as a coating for recording and stimulating electrodes. In this presentation, the role of deposition oxygen partial pressure (OPP) leading to high-aspect-ratio IrO2 micro/nano-structures will be reported. In contrast to microstructural differences induced by varying pressure, the microstructures induced during deposition as a function of OPP improve charge coupling as measured by electrochemical charge storage capacity measurements. Furthermore, if the high aspect ratio structures are suppressed, the electrochemical performance of the coatings is improved at higher OPP. The role of substrate temperature will also be discussed.