Micromachined electrodes for retinal prostheses

High-resolution retinal prosthetic systems need high-density stimulation electrodes to restore the vision of blind patients suffering from retinitis pigmentosa or macular degeneration. Micromachining electrodes to obtain high-aspect-ratio features can increase the area of the electrodes. A process has been developed to obtain high-aspect-ratio microstructures by plating on the sidewall of recently developed photoresist. A quadrupling of the effective area of the electrode surface has been achieved with modest micromachining and could translate into an improvement in visual resolution. A remaining issue is reducing irreversible electrochemical reactions at the electrode.