Natalie Page¹, Gregory Taylor¹, John Lucchi^1,4, Rhandy Paladines¹, Anthony Marti¹, *Jeffrey Hettinger¹, Saxon Tint², Shahram Amini^2,5, Andy Fones³, Hugh Hamilton^3
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.