Microfabrication of disposable microfluidic devices featuring porous polymer monoliths for on-chip electrochromatography.

摘要

A plastic injection molding process was developed for rapid, high-volume production of plastic microfluidic chips featuring a novel integrated fluidic port. The microfluidic channels are defined by a robust mold insert that is reversibly loaded onto the mold base. This solid metal mold insert was microfabricated by electrochemically depositing nickel in the open areas of a negative-tone, thick photoresist defined using contact photolithography. Chips bonded by conventional thermal lamination and a novel solvent vapor process were qualitatively compared by microscopy and quantitatively tested for bond strength by burst pressure measurement. Following device fabrication the channels were surface modified by UV-initiated polymerization reactions to create a thin, chemically reactive skin that covalently anchors the stationary phase prepared in the subsequent step. To circumvent the difficulties associated with packing beads in a microfluidic chip, porous polymer, monoliths were patterned directly within the microfluidic chip using an in situ UV-mediated preparation method. The ability to spatially confine monolith to well defined areas of the chip using UV light facilitated the patterning of a column featuring an optical detection window. Device fabrication was completed upon serially photografting the monolith surface with an ionizable monomer for support of electroosmotic flow followed by a hydrophobic monomer to increase the reverse phase retention time.