Fabrication of a miniaturized liquid chromatography separation channel on silicon

After a brief introduction discussing the possibilities of a miniaturized liquid chromatography system and some of the problems that need to be addressed, this paper will detail the fabrication sequencing for a separation μ-channel and connection ports for the optional connection of the device to external instrumentation. The channels and connection ports have been etched in silicon and then sealed with a Pyrex™ (Corning Ltd., Buckinghamshire, U.K.) coverplate using an anodic bonding technique giving a backpressure capability of greater than 1500 psi. The fabricated demonstrators were of a variety of designs and dimensions; one μ-channel (50 μm in width, 16 cm in length, and 5.7 μm in depth) was modified with a triethoxysilane phase and then interfaced with a nano-LC system. The successful separation of a mixture of benzamide and biphenyl was achieved in approximately 2 min with off-chip UV detection and a 20-nL injection volume, demonstrating the feasibility of a miniaturized system.