Lab-on-a-chip systems with three dimensional microelectrodes

This paper reports on the development and testing of a self-contained portable electrochemical (EC) detection platform capable of monitoring heavy metals (Pb, Cu etc.). Towards this end, a lab-on-a-chip (LOC) device was fabricated by etching a microchannel system into a soda lime glass substrate and incorporating photo-lithographically patterned radial gold microelectrodes at the end of the designated separation channel. The first pair of electrodes was modified into a single 3D microelectrode whose high surface area is ideal for effective pre-concentration of metals ions in a sample stream, while the other 2 pairs were unmodified and used as planar "sensing" electrodes. Proper control of plating and stripping voltages at the 3D microelectrode yielded initial pre-concentration and subsequent release of Cu/sup 2+/ ions, which were then detected downstream at the one of the planar electrodes.