應用電動力於毛細管電泳微流體晶片

Abstract

近年來，微流體晶片被廣泛地運用在生醫檢測上。而一般微流體晶片需要帶有實體邊壁的流道來侷限住流體移動範圍，於是本研究的重點是利用液介電泳原理在微流體晶片兩板間建立無實體邊壁之虛擬微流道，並在此虛擬微流道的兩端施加直流電壓進行毛細管電泳分析，此晶片具有不需使用實體流道結構、外加幫浦與可動閥門，以及可程式操控微流體等特色。 實驗中，透過晶片上下板的電極圖形定義虛擬微流道布局，並利用觀察不帶電之螢光粒子進行電滲流流速的量測。透過在一個無定義圖案的電極上板與一個定義虛擬微流道圖案的電極下板之間充滿矽油，並施加100 kHz、80 Vrms之交流電壓在兩板之間時，含有20 mM Borax和5 mM SDS的緩衝液將會沿著下板電極圖樣在兩板之間形成長3 cm、寬500 um、高30 um之虛擬微流道。 本研究對兩板之間施加不同的電壓對電滲流流速的影響進行探討。當提升施加於兩板之間的交流電壓自69 Vrms至110 Vrms時，並未觀察到電滲流流速明顯變化。而在額外施加直流電壓於兩板之間並提升此直流電壓自5 V至15 V時，觀察到電滲流流速自18 um/s改變至39 um/s的明顯上升現象。本研究亦探討了在流道兩端施加不同的電壓對電滲流流速的影響，當提升流道兩端的直流電壓自20 V至40 V時，電滲流流速自18 um/s線性上升至39 um/s。

Microfluidic chips have been widely used in the biomedical analysis in recent years. In general, most microfluidic chips employ the physical channel wall to confine the liquid. Different from previous studies on physical channel wall, liquid dielectrophoresis-formed wall-less virtual microchannel is proposed in this study. Furthermore, a DC field was applied along the virtual microchannel to induce the capillary electrophoresis. These chips offer a number of advantages, such as simple configuration, absence of moving parts moving part, and programmable control. The geometry of virtual microchannel was determined by the electrode patterns on both top plate and bottom plate. Neutral fluorescent polystyrene beads are used to indicate the velocity of electroosmotic flow (EOF). When a 80 Vrms with 100 kHz signal was applied, the liquid containing 20 mM Borax buffer and 5 mM sodium dodecyl sulfate formed a virtual channel with 3 cm in length, 500 um in width, and 30 um in height in the medium of silicone oil. The effect of EOF velocity due to different voltages applied between two plates is investigated first. When the AC voltage was increased from 69 Vrms to 110 Vrms, the variation of EOF velocity was not obvious. When the DC bias voltage was increased from 5 V to 15 V, the EOF velocity increased from 18 um/s to 39 um/s. The effect of different voltages on the both ends of the virtual microchannel is also studied here. When the DC voltage was increased from 20 V to 40 V, the EOF velocity increased from 18 um/s to 39 um/s linearly.