Iridium-Based Ultramicroelectrode Array Fabricated by Microlithography

Samuel P. Kounaves,* Wen Deng, and Pamela R. Hallock
Department of Chemistry, Tufts University, Medford, Massachusetts 02155

Gregory T. A. Kovacs and Christopher W. Storment
Center For Integrated Systems, Stanford University, Room CIS 130, M/C 4070, Stanford, California 94305

* Corresponding Author

Abstract

A microlithographically fabricated iridium ultramicroelectrode array is used to provide a disk array for formation of mercury microhemispheres. The mercury ultramicroelectrode array (Hg UMEA) shows a response with chromoamperometry and square wave anodic stripping voltammetry equivalent to that expected for a single Hg UME. The array, made up of 19 interconnected 10mm diameter UMEs, provides a multiplication of the signal current proportional to the number of UMEs in the array, without any indications of overlap of the diffusion fields. Deposited mercury on the iridium disks is physically and chemically stable with no indication of degradation or dissolution of the iridium pads even after several days of use. This microlithographically fabricated device provides a stable, well-defined, and reproducible array of mercury ultramicroelectrodes. The analytical utility and performance of the Hg UMEA is demonstrated by the analysis of Cd(II), Pb(II), and Cu(II) in neat spring water samples.