Electrodes with submicron gaps are desired for achieving high amplification redox cycling sensors. In this contribution we report the use of electrodeposition of gold in order to decrease the inter-electrode spacing at interdigitated electrodes. Using this method submicron spacings can be obtained without expensive techniques such as e-beam lithography or focused ion beam milling. Initially, gold interdigitated electrodes with a finger spacing of 2.5 μm were realized by lift-off processing. Using a commercial gold sulphite bath (ECF64D) and 100 ms current pulses of -1.78 μA, these gold electrodes were plated with an additional gold layer. As a result, the inter-electrode spacing, as measured using atomic force microscopy and conventional microscopy, was reduced to 0.6 μm. The achieved gap spacing is limited by electrode imperfections resulting from the lift-off process. At these imperfections the electrodes become shorted. Additional experiments with wet etched electrodes are expected to yield smaller gap spacings.
|Number of pages||4|
|Publication status||Published - 2014|