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T자형 마이크로 채널 내부 전기삼투 유동의 불안정성 가시화
한수동(Su Dong Han),이상준(Sang Joon Lee) 한국가시화정보학회 2005 한국가시화정보학회지 Vol.3 No.2
Electro-osmotic flow (EOF) instability in a microchannel has been experimentally investigated using a micro-PIV system. The micro-PIV system consisting of a two-head Nd:Yag laser and cooled CCD camera was used to measure instantaneous velocity fields and vorticity contours of the EOF instability in a T-shape glass microchannel. The electrokinetic flow instability occurs in the presence of electric conductivity gradients. Charge accumulation at the interface of conductivity gradients leads to electric body forces, driving the coupled flow and electric field into an unstable dynamics. The threshold electric field above which the flow becomes unstable and rapid mixing occurs is about 1000V/cm. As the electric field increases, the flow pattern becomes unstable and vortical motion is enhanced. This kind of instability is a key factor limiting the robust performance of complex electrokinetic bio-analytical devices, but can also be used for rapid mixing and effective flow control for micro-scale bio-chips.
한수동(Su Dong Han),김국배(Guk Bae Kim),이상준(Sang Joon Lee) 대한기계학회 2005 대한기계학회 춘추학술대회 Vol.2005 No.11
A syringe pump or a device using a high electric voltage has been used for controlling flows inside a LOC (lab-on-a-chip). Compared to LOC, however, these devices are so large and heavy that they are burdensome in the development of a portable μ-TAS (micro total analysis system). In this study, a new flow control technique employing pressure regulators and pressure chambers was developed. In addition, the performance of this flow control system was compared with that of a conventional syringe pump. The developed flow control system was found to have superior performance compared to the syringe pump. It maintains automatically the air pressure inside a pressure chamber whether the flow inside a capillary tube is on or off.