Cation-Doped IrO₂ Electrode for Improved Charge Storage Capacity in Bioelectronics Applications

Bioelectrodes play a crucial role in bioelectronic sensing and neural therapy. The primary materials used for bioelectrode substrates include platinum, titanium nitride, tantalum pentoxide, and iridium oxide. Among these, iridium oxide has garnered attention for its low impedance and high charge storage capacity which is suitable for active bio-stimulation applications. Our laboratory has synthesized iridium oxide electrodes doped with Na⁺, K⁺, or Mg²⁺ on ITO substrate. We utilize XPS and XAS to confirm the changes in the iridium oxidation state post-ion doping, aiming to study the chemical structure alterations resulting from the doping process. CSC of cation ion doped IrO₂electrode is determined by CV which showed excellent results, Na⁺ doped IrO₂: 0.31 mC cm^-2 nm ^-1, K⁺ doped IrO₂: 0.31 mC cm^-2 nm ^-1, Mg²⁺ doped IrO₂: 0.37 mC cm^-2 nm^-1. After 1,000 CV cycles, the CSC of the IrOx thin films remained relatively consistent.