Fabrication of PMMA Microchip of Capillary Electrophoresis by Optimized UV-LIGA Process

Design and fabrication of microfluidic devices on polymethylmethacrylate (PMMA) substrates for electrochemical analysis applications using improved UV-LIGA process are described. The micro-channel structures are transferred from Nickel mould into the plastic plates by hot embossing method. During the mould fabrication, the exposure process is optimized for the large ratio of exposed area to unexposed area of negative photo-resist (SU-8), then non-planar electroforming technique is used for the large line space of the SU8 photo-resist mold. Microelectrodes for electrochemical detection are fabricated on other blank PMMA plates through lift-off process. Then these substrates with microchannels are bonded to PMMA plates with microelectrodes by thermal bonding method based on surface modification. In this study, the PMMA microchips of capillary electrophoresis for electrochemical detection (CE-ECD Chips) have been demonstrated by electrophoretic separation of L-ascorbic and uric acid. The results indicate that the fabrication of CE chips by this improved UV-LIGA process has potential of mass production with low cost.