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

We report on the successful development of Hg-plated-iridium based microelectrode arrays intended to heavy metal trace analysis. The iridium microdisk arrays were achieved by using microelectronic processing techniques. These conducting-base arrays consist of 30×30 of 5 μm dia. iridium microdisks spaced 180 μm from each other. They were systematically characterized by means of cyclic voltammetry and found to exhibit a steady-state voltammetric behavior. Prior to metal trace analysis, mercury was electroplated on the iridium microdisk arrays. The latters were found to sustain the mercury film formation-and-dissolution operation at least 15 times. The electroanalytical performances of the fabricated Hg-plated-iridium microelectrode arrays were evaluated by means of multiple square wave anodic stripping voltammetry (MSWASV) in synthetic solutions of Pb and Cd ions. Over the (500 ng l−1–15 μg 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 concentration, 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 μg l−1 and a preconcentration time of 5 min.