Fabrication of poly(dimethylsiloxane)-based capillary electrophoresis microchips using epoxy templates

A novel method for the fabrication of poly(dimethylsiloxane) (PDMS)-based capillary electrophoresis (CE) microchips using epoxy templates is described. A PDMS plate containing the channel structure was replicated from a hard master with the positive relief of negative photoresist on a silicon wafer by replica molding. It was used as a soft mold to produce the positive relief of a hard epoxy template for molding of the final soft PDMS micro devices. The present hard-to-soft, soft-to-hard, and hard-to-soft micro fabrication method offers a promising way for the mass production of PDMS microchips, epoxy and other hard polymer templates. The epoxy templates are durable for molding PDMS electrophoresis microchips because of its higher mechanical strength. High chip-to-chip reproducibility has been found with relative standard deviations (n = 30) of 3.7 and 4.1% for the widths (49.2 mu m) and depths (41.5 mu m) of the replicated channels in the final PDMS substrates, respectively. The feasibility and performance of the PDMS microchips fabricated by the new method have been demonstrated by separating and detecting dopamine and catechol in connection to end-column amperometric detection. Factors influencing the analytical performance of the microsystem for the separation of the two analytes have been characterized and optimized.