Transparent and flexible ECoG electrode arrays based on silver nanowire networks for neural recordings
AbstractThis work explored hybrid films of silver nanowires (AgNWs) with indium-doped zinc oxide (IZO) for developing high-performance and low-cost electrocorticography (ECoG) electrodes.The hybrid films achieved a sheet resistance of 6 Ω/sq while maintaining a transparency of ≈60% at 550 nm. Electrodes with 500 μm diameter were fabricated with these films and reached an impedance of 20 kΩ at 1 kHz and a charge storage capacity of 3.2 mC/cm2, a 2× and 320× improvement over IZO electrodes, respectively. Characterization of light-induced artifacts was performed showing that small light intensities (<14 mW/mm2) elicit electrical potential variation in the magnitude order of baseline noise. The validation of electrodes in vivo was achieved by recording electrical neural activity from the surface of rat cortex under anaesthesia. Moreover, the presence of the films did not cause obstruction of light during fluorescence microscopy.The presented film and electrode characterization studies highlighted the capabilities of this hybrid structure to fabricate transparent and flexible electrodes that are able to combine the superior temporal resolution of extracellular electrophysiology with the spatial resolution offered by optical imaging.