Fabrication of Micro/Nanofluidic Chip on Glass Substrate and Its Application for Electrokinetic Concentration of Proteins

A simple and cost-effective double-lithography and double wet-etching method (abbriciated as double-etching technique) was developed for fabricating the full glass chips with hybrid micro- and nanochannels. The microchannels were firstly constructed on a glass substrate by standard UV photolithography and wet etching technique. After washing away the rest photoresist and spin coating of a new layer of photoresist on the microchannel-structured glass substrate, nanochannels with a depth less than 100 nm were prepared on the same substrate by second lithography and wet etching. Finally, the channel-structured glass substrate was sealed to a cover glass plate using room temperature bonding technique. Without clean room facilities and expensive facilities, fluidic chips with hybrid micro- and nanochannel network were fabricated with high yields. The analytical features of those fluidic chips were demonstrated by the successful concentration of fluorescein isothiocyanate(FITC)-labeled human serum albumin(HSA) via electrokinetic ion trapping. Enrichment factor of more than 200 was achieved for 0.5 mg/mL of FITC-HSA solutions within 30 s.