Stability of impedance characteristics at the microelectrode-saline interface

Stability of the impedance characteristics of gold-plated indium-tin-oxide microelectrodes within a microelectrode array is discussed. Microelectrodes, immersed in isotonic saline, are exposed to continuous current applications at frequencies from 100 Hz to 10 kHz, resulting in current densities of from 1 to 300 pA/μm². The impedance characteristics are monitored for time periods ranging from 1 to 8 h. At each frequency and current density level, the resistance, capacitance, and total impedance are found to be relatively stable, although some drift is observed. The relative effect of resistance and capacitance on the impedance is examined as a function of frequency and current density