Individually Addressable, Submicrometer Band Electrode Arrays. 2. Electrochemical Characterization

Abstract

We report extensive cyclic voltammetric evaluation of gold submicrometer edge band electrodes with different widths, from 25.3 to 143.5 nm. Fabrication of these band electrodes from layers of gold and silicon nitride using conventional microfabrication techniques, was reported in the preceding companion paper. Gold film thicknesses and, thus, the electrode widths were measured by surface profilometry, X-ray interferometry, and atomic force microscopy. The electrodes exhibit typical sigmoidal-shaped cyclic voltammograms at slow scan rates (<1 V/s). The limiting currents deviate from theoretical values as electrode width decreases. At larger widths, experimental values are in better agreement with theory, consistent with trends reported in the literature. Maximum current is much higher than expected for all widths at fast scan rates (> 25 V/s). Capacitance of the edge band electrodes is high (187−0.206 mF/cm2 for 71.2-nm edge band electrodes for scan rates of 0.010−204 V/s) and scan rate dependent. Values approach those of macroelectrodes at fast scan rates, indicating imperfect seals at the gold/silicon nitride, gold/Cr/glass, or gold/epoxy interfaces.