Combining Micromachining and Molecular Self-Assembly To Fabricate Microelectrodes

This paper describes three types of gold electrodes, each with at least one spatiai dimension as small as 1 prm, fabricated using combinations of micromachining and molecular self-assembly. (i) Large-area (>0.1 mm2) arrays of band-type electrodes were formed by machining micrometer-wide grooves of bare gold into gold frlm covered with a -23-A-thick, electrically insulating, self-assembled monolayer (SAM) of CHs(CHz)rsS. (ii) Micrometer-wide, centimeter-long, 100-nm-thick gold electrodes supported on glass were fabricated by patterning a gold film with monolayers of CHs(CHz)rsS and HO(CHz)zS, and selectively etching the regions of gold covered with HO(CHz)zS using an aqueous solution of CN saturated with Oz. (iii) T\vo microelectrodes, each with electrochemically active areas as small as 100 nm x l rrm and separated from each other by a distance of I !rm, were formed by machining a l-pzm-wide gap into a supported gold wire covered with an electrically insulating SAM of CHs(CHz)rsS; exposed gold on either side of the machined gap formed the electrochemically active surfaces of the microelectrode pair.