Miniaturized electrochemical flow cells.

Abstract

Several novel types of miniaturized electrochemical flow cells are described. The flow cells are fabricated in fluorinated ethylene propylene using a novel technique where channels with inner diameters down to 13 microm are integrated with electrodes. The channel is formed by shrinking and simultaneous melting of a heat shrink/melt tubing around a channel template (a tungsten wire) and electrodes followed by removal of the channel template. The technique allows incorporation of different electrode materials of different sizes. The electrode configuration consists of one or two working electrodes inside the channel and a counter electrode located in the channel outlet reservoir. Electrode configurations with different channel and working electrode sizes, different electrode materials including carbon fibers, glassy carbon rods, poly(tetrafluoroethylene)/carbon composite material, and platinum wires, and different arrangements have been assembled. Hydrodynamic voltammograms in dual-electrode (generator-collector) experiments indicate good potential control for cells with 25-microm channels, while there is some iR drop in cells with 13-microm channels. Cells prepared with a cylindrical working electrode tangent and perpendicular to a flow channel show a flow rate dependence consistent with thin-layer cell behavior. Electrode areas can be made in the range of 10(-10)-10(-8) m2.