Characterization of Electrochemical Array Detection for Continuous Channel Electrophoretic Separations in Micrometer and Submicrometer Channels

Characterization of a microfabricated electrochemical array detection scheme used for continuous electrophoretic separations in narrow channels is described. The amperometric detector consists of 100 platinum microelectrodes (95 μm wide, 1.2-2 mm long, 0.12 μm high, each spaced by 5 μm) and has been previously used in channel structures with internal heights as small as ∼21 μm. Here, the ability to differentiate both mass and concentration changes of dopamine is demonstrated in 8-μm-internal height channel structures with electrochemical detection. Characterization of the array detector to provide insight into the nonuniform sensitivity observed with the microfabricated electrophoresis-electrochemical array detection technique is detailed. Approaches to circumvent the nonuniform sensitivity of the microelectrode array are described. Finally, we push the limits of the fabrication technology with the construction and use of submicrometer internal height (∼0.6 μm) rectangular channel structures.