Fabrication of iridium oxide/platinum composite film on titanium substrate for high-performance neurostimulation electrodes

Electrode materials for neural stimulation have been widely investigated for implantable devices. Among them, iridium and iridium oxide are attractive materials for bio-interface applications due to their desirable stability, electrochemical performance, and biocompatibility. In this study, iridium oxide/platinum (IrO_x/Pt) composite films were successfully fabricated on titanium substrates by chemical bath deposition and these films are expected to be used as biocompatible stimulation electrodes. We modified the film compositions to optimize the performances. In addition, these IrO_x/Pt composite films were characterized before and after annealing by SEM and XRD.We also identified the hydrophilicity of these iridium oxide/platinum composite films by measuring contact angles. Finally, the charge storage capacities of these iridium oxide/platinum composite films were evaluated by an electrochemical workstation. As a result, the charge storage capacities of the iridium oxide/platinum composite films are largely increased, and this leads to a very efficient neurostimulation electrode. Additionally, we successfully demonstrated the chemical bath deposition of IrO_x film on the surface of the bullet-shaped titanium microelectrode.