IRIDIUM-BASED ULTRAMICROELECTRODE ARRAY FABRICATED BY MICROLITHOGRAPHY

A microlithographically fabricated iridium ultramicroelectrode array i s used to provide a disk array for formation of mercury microhemispher es. The mercury ultramicroelectrode array (Hg UMEA) shows a response w ith chronoamperometry and square wave anodic stripping voltammetry equ ivalent to that expected for a single Hg UME. The array, made up of 19 interconnect ed 10-mu m-diameter UMEs, provides a multiplication of t he signal current proportional to the number of UMEs in the array, wit hout any indications of overlap of the diffusion fields. Deposited mer cury on the iridium disks is physically and chemically stable with no indication of degradation or dissolution of the iridium pads even afte r several days of use. This microlithographically fabricated device pr ovides a stable, well-defined, and reproducible array of mercury ultra microelectrodes. The analytical utility and performance of the Hg UMEA is demonstrated by the analysis of Cd(II), Pb(Il), and Cu(II) in neat spring water samples.