Patterned iridium oxide film as neural electrode interface: Biocompatibility and improved neurite outgrowth with electrical stimulation

Iridium (Ir) thin film was deposited on patterned titanium substrate by direct-current (DC) magnetron sputtering, and then activated in sulfuric acid (H2SO4) through repetitive potential sweeps to form iridium oxide (IrOx) as neural electrode interface. The resultant IrOx film showed a porous and open morphology with aligned microstructure, exhibited superior electrochemical performance and excellent stability. The IrOx film supported neural stem cells (NSCs) attachment, proliferation and improved processes without causing toxicity. The patterned IrOx films offered a unique system to investigate the synergistic effects of topographical cue and electrical stimulation on neurite outgrowth. Electrical stimulation, when applied through patterned IrOx films, was found to further increase the neurite extension of neuron-like cells and significantly reorient the neurite alignment towards to the direction of stimulation. These results indicate that IrOx film, as electrode-tissue interface is highly stable and biocompatible with excellent electrochemical properties.