A measurement set-up to determine the charge injection capacity of neural microelectrodes

A measurement set-up is presented which can be used to determine the charge injection capacity of neural microelectrodes. This value determines the amount of charge that can be reversibly injected during a single stimulation pulse, and is strongly depending on the materials present at the electrode/electrolyte interface. The set-up was used to measure and compare the charge injection capacity of various electrode materials (sputtered platinum, microporous platinum, PEDOT), and for various stimulation pulse widths. It was observed that the charge injection capacity for microporous platinum und PEDOT was significantly higher than for sputtered platinum. Moreover, the charge injection capacity was found to increase with the stimulation pulse width.