title: Characterization of electrokinetic gating valve in microfluidic channels.
abstract: Electrokinetic gating, functioning as a micro-valve, has been widely employed in microfluidic chips for sample injection and flow switch. Investigating its valving performance is fundamentally vital for microfluidics and microfluidics-based chemical analysis. In this paper, electrokinetic gating valve in microchannels was evaluated using optical imaging technique. Microflow profiles at channels junction were examined, revealing that molecular diffusion played a significant role in the valving disable; which could cause analyte leakage in sample injection. Due to diffusion, the analyte crossed the interface of the analyte flow and gating flow, and then formed a cometic tail-like diffusion area at channels junction. From theoretical calculation and some experimental evidences, the size of the area was related to the diffusion coefficient and the velocity of analytes. Additionally, molecular diffusion was also believed to be another reason of sampling bias in gated injection.
authors: The Key Laboratory of Biomedical Photonics of MOE, Hubei Bioinformatics & Molecular Imaging Key Laboratory, Department of Systems Biology, College of Life Science & Technology, Huazhong University of Science and Technology, Wuhan 430074, China.
authors: Guiseng
authors: G
authors: Zhang
authors: Wei
authors: W
authors: Du
authors: Bi-Feng
authors: BF
authors: Liu
authors: Hideaki
authors: H
authors: Hisamoto
authors: Shigeru
authors: S
authors: Terabe
mesh_terms: D004396:Coloring Agents / Q000032:analysis*; D004058:Diffusion; D004563:Electrochemistry / Q000379:methods*; D016650:Fluorescein-5-isothiocyanate; D007700:Kinetics; D008832:Microchemistry / Q000379:methods*; D046208:Microchip Analytical Procedures / Q000379:methods; D012235:Rhodamines; D012984:Software
chemical_list: D004396:Coloring Agents; D012235:Rhodamines; D016650:Fluorescein-5-isothiocyanate