本研究以自組裝單分子層技術改質微管道壁面，並使用電滲流驅動流體的方式，設計能匯聚樣品的爪型微管道裝置。首先，藉由表面改質使微管道壁面帶正電，並利用電流觀測法評估改質面的ζ-potential值。然後找出適當的操作條件，使受改質壁面的正ζ-potential值與受氧電漿照射壁面的負ζ-potential值，兩者的絕對值相近。在這操作條件下，觀察螢光粒子流經爪型微管道轉角的軌跡，並與CFD-ACE+軟體模擬出的流場比較，結果顯示螢光粒子不會因直流介電泳作用而改變流動軌跡。因此，當匯聚的螢光粒子流經爪型管道轉角時，直流介電泳的作用並不會影響匯聚效果。此外，藉由調控側支管與中央進料管內緩衝溶液的濃度比，可改變微管道裝置內的電場強度，以控制支管與中央管的電滲流流速比。當兩者的流速比越高時，匯聚流的寬度會越窄，因而可以達到操控匯聚流寬度的目的。

In this study, a claw-shaped microchannel device for focusing the sample flow was designed with the surface modification of the microchannel by the self-assembled monolayer technique and with the fluid flow driven by the electroosmosis. The positively charged surface of a microchannel was fabricated first by the surface modification, and the zeta potential of the modified surface was evaluated by the current-monitoring method. The proper operation condition, at which the absolute values of the positive zeta potential of the modified surface and the negative zeta potential of the surface exposed to oxygen plasma were close, was then found. Under this operation condition, the tracks of fluorescence particles flowing through the corner of the claw-shaped microchannel device were observed and compared with the fluid field obtained by the simulation with the CFD-ACE+ software. The results indicated that the flowing tracks of the fluorescence particles were not varied by the DC-dielectrophoresis. Therefore, the focusing efficiency was not influenced by the DC-dielectrophoresis when the particles flowed through the corner of the claw-shaped microchannel device. Moreover, the electric field in the microchannel device could be changed by adjusting the concentration ratio of the buffer solutions in the side and central channels, and thus the velocity ratio of the electroosmotic flows in the side and central channels could be controlled. When the velocity ratio became higher, the width of the focused flow was smaller, and the purpose of controlling the width of the focused flow could be attained.

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