In vitro life tests of Faradaic neural stimulation electrodes at high current densities

Membrane-coated Ag/AgCl, uncoated iridium, and membrane-coated iridium electrodes were pulsed with typical neural stimulation waveforms in vitro in 0.13-M NaCl. Life tests were made at various current densities for periods of time up to 2000 h. Iridium electrodes performed successfully at higher current densities that smooth platinum, but membrane-coated Ag/AgCl was no better than platinum. Shape change appears to limit the life of both iridium and Ag/AgCl electrodes at high current densities and charge densities.