Development of Hg-electroplated-iridium based microelectrode arrays for heavy metal traces analysis

We report on the successful development of Hg-plated-iridium based microele ctrode arrays intended to heavy metal trace analysis. The iridium microdisk arrays were achieved by using microelectronic processing techniques, These conducting-base arrays consist of 30x30 of 5 mu m dia, iridium microdisks spaced 180 mu m from each other. They were systematically characterized by means of cyclic voltammetry and found to exhibit a steady-state voltammetri c behavior. Prior to metal trace analysis, mercury was electroplated on the iridium microdisk arrays, The latters were found to sustain the mercury fi lm formation-and-dissolution operation at least 15 times, The electroanalyt ical performances of the fabricated Hg-plated-iridium microelectrode arrays were evaluated by means of multiple square wave anodic stripping voltammet ry (MSWASV) in synthetic solutions of Pb and Cd ions. Over the (500 ng l(-1 )-15 mu g l(-1)) concentration range, the detected signal of both Cd and Pb was found to exhibit a strong linear correlation with not only the ion con centration, but also the preconcentration time. The mercury microelectrode array based sensors were found to exhibit a good stability over a period of about 5 h, for Cd concentration as low as 1 mu g l(-1) and a preconcentrat ion time of 5 min. (C) 1999 Elsevier Science B.V. All rights reserved.