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We present the experimental study to realize a DNA separation chip using asymmetrically-switched nonuniform electric fields. The DNA separation chip redistributes DNA molecules within a specific area based on the size- and field-dependent nonlinearity of DNA drift velocity. The present chip is composed of a width variable channel to distribute nonuniform electric field, a DNA loading slit and a pair of electrodes to apply electric field. We focus on the design of DNA separation chips with identifying the nonlinearity of DNA drift velocity using three different DNA molecules (11.1kbp, 15.6kbp, and 48.5kbp) in the chips. It is demonstrated that different size of DNA shows different net migration in different direction under the asymmetrically-switched n onuniform electric field.기호설명 E 전기장 T 전기장 인가 주기 M DNA 분자의 크기 1. 서론 본 연구은 DNA 분리소자에 관한 것으로, 채널 내에 형성된 불균일한 전기장의 방향이 변함에 따라, DNA는 그 6cm크기에 따라 알짜이동 방향과 속도가 달라지게 된다. 본 논문에서는 이론적으로 제시된 바 있는 (1)이러한 래칫(ratchet) 효과를 실험적으로 검증하였다. 제안한 DNA분리소자(Fig. 1)에서는 비대칭 교차전기장(Fig. 2) 6mm미소유로을 양단에 인가하고 미소유로의 폭을 변화시켜 불균일 전기장을 형성하였다. 기존의 전기영동 소자

We present a novel flow-rate independent cell counter using a fixed control volume between double electrical sensing zones. The previous device based on the single electrical cell sensing in a given flow-rate requires an accurate fluid volume measurement or precision flow rate control. The present cell counter, however, offers the flow-rate independent method for the cell concentration measurement with counting cells in a fixed control volume of . In the experimental study, using the RBC (Red Blood Cell), we have compared the measured RBC concentrations from the fabricated devices with those from Hemacytometer. The previous and present devices show the maximum errors of , which are in the measurement error range of Hemacytometer (about ). The present device also shows the flow-rate independent performance at the constant flow-rates ( and ) and the varying flow-rate (4, 2, and ). Therefore, we demonstrate that the present cell counter is a simple and automated method for the cell concentration measurement without requiring an accurate fluid measurement and precision flow-rate control.