MP34:Use of Epoxy-Embedded, High-Aspect Ratio Pillar Electrodes for Microchip-Based Systems

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A. Selimovic, A. Johnson, I.Z. Kiss and R. S. Martin
Dept. of Chemistry, Saint Louis University

This presentation will describe a new approach for microelectrode fabrication of planar and pillar electrodes that can be integrated into microfluidic channels. The electrodes sizes can be easily varied from 1mm to 25 microns in diameter and the resulting embedded electrodes can be reversibly sealed against a PDMS-based fluidic network for introduction of pressure-based flow. Gold planar electrodes have been used to detect catechol samples for characterization and the selective detection of glutathione was achieved via a mercury amalgamation. While the planar electrodes are easy to fabricate and enable the use of different electrode materials, electro-deposition of gold or gold-silver mixtures onto the epoxy embedded electrodes allows for creation of high aspect pillar electrodes. This is a first time a group has developed an easy, inexpensive, fast, and reproducible way of making 3D electrodes for in-channel detection. Gold depositions for creation of pillar electrodes were optimized to achieve tenfold higher surface area and signal than planar electrodes of the same diameter. These pillars can be made in a 4-electrode array, resulting in a quadrupling of analyte signal compared to use of a signal pillar. Electrical deposition of gold-silver mixture give rise to branched pillars, allowing a tenfold increase in surface area over a gold pillar of the same height. Characterization of electrode depositions, flow performance, life time stability, reproducibility, and electrode surface area calculations will be presented in this poster.

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