Bias voltages at microelectrodes change neural interface properties in vivo

Rejuvenation of iridium microelectrode sites, which involves applying a 1.5 V bias for 4 s, has been shown to reduce site impedances of chronically implanted microelectrode arrays. This study applied complex impedance spectroscopy measurements to an equivalent circuit model of the electrode-tissue interface. Rejuvenation was found to cause a transient increase in electrode conductivity through an IrO₂ layer and a decrease in the surrounding extracellular resistance by 85 ± 1% (n=73, t-test p < 0.001) and a decrease in the immediate site resistance by 44 ± 7% (n=73, t-test p<0.001). These findings may be useful as an intervention strategy to prolong the lifetime of chronic microelectrode implants for neuroprostheses.