title: Bias-free pneumatic sample injection in microchip electrophoresis.
abstract: We have developed a new microfluidic chip capable of accurate metering, pneumatic sample injection, and subsequent electrophoretic separation. The pneumatic injection scheme, enabling us to introduce a solution without sampling bias unlike electrokinetic injection, is based upon the hydrophobicity and wettability of channel surfaces. An accurately metered solution of 10 nL could be injected by pneumatic pressure into a hydrophilic separation channel through Y-shaped hydrophobic valves, which consist of polydimethylsiloxane (PDMS) and fluorocarbon (FC) film layers. We demonstrated the successful pneumatic injection of a red ink solution into the separation channel as a proof of the concept. A mixture of fluorescein and dichlorofluorescein (DCF) could be baseline-separated using a single power source in microchip electrophoresis.
authors.affiliation: School of Electrical Engineering and Computer Science, Seoul National University, Seoul 151-744, Republic of Korea.
authors.forename: Seung Il
authors.initials: SI
authors.lastname: Cho
authors.forename: Sang-Ho
authors.initials: SH
authors.lastname: Lee
authors.forename: Doo Soo
authors.initials: DS
authors.lastname: Chung
authors.forename: Yong-Kweon
authors.initials: YK
authors.lastname: Kim
mesh_terms: D046209:Electrophoresis, Microchip / Q000295:instrumentation*; D019793:Fluorescein / Q000302:isolation & purification; D005452:Fluoresceins / Q000302:isolation & purification; D008904:Miniaturization
chemical_list: D005452:Fluoresceins; C037631:2',7'-dichlorofluorescein; D019793:Fluorescein