液滴共振混合

數位微流操控法擁有傳統微熱流領域所無法比擬的優點因而備受矚目，故此液滴驅動、混合以及分離等技術儼然已成為一大課題。本研究架構於數位液滴EWOD驅動系統上，以液滴於共振頻所產生之最大振幅與渦流作為液滴混合的動力源，藉此快速達到混合效果並可節省電極空間。研究成果發現，液滴在雙平面EWOD時，其空間受制於上板使得振盪行為與單平面EWOD大相逕庭，導致液滴的共振頻率均較單平面EWOD時為大，此外，實驗結果發現當雙平面間距縮小時，液滴與電極的接觸面積增大，液滴的共振頻率將會變小，此與前人之研究相符。實際觀察混合效率，7 μl液滴在共振頻的混合效率均較其他頻率為高，尤以共振頻165 Hz在電外場300 V時混合效果最佳，所需時間僅為自然擴散混合之6.7%，便可達到預計混合效果。文末，本研究亦發現若改用雙共振頻率互換之方法，由於內部渦流的交替改變可再提升液滴的混合效率。

關鍵字

介電潤濕現象；共振現象；混合

並列摘要

Digital microfluidics has the incomparable advantages over the traditional ones, making the research of manipulating, mixing and separating of droplets a major topic. The mixing efficiency, implemented by the effect of EWOD, can be highly improved by actuation of droplets under its resonance frequency which creating the maximal amplitude and internal flow vortex while oscillation. The results show that two-plate EWOD, limited by the space, has larger resonant frequency with comparison of single planar EWOD. Also this article demonstrated that the narrower the gap between the electrodes is, the wider the droplet’s contact areas are. The result complies with the literature. Conclusion is that droplet of 7 μl volume has better mixing efficiency when actuated under the resonant frequency. Among the resonant frequencies, 165 Hz attains the best result, with the time for only about 6.7% of mixing by natural diffusion. In addition, we found that, by alternating periodically two driving frequencies, can the mixing efficiency be achieved to a greater extent.

並列關鍵字

EWOD ； resonant ； droplet mixing

參考文獻

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[3] C.G. Cooney, C.Y. Chen, M.R. Emerling , A. Nadim, J.D. Sterling, "Electrowetting droplet microfluidics on a single planar surface," Microfluid Nanofluid , 2006, 2, 435-446

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[5] M.F. Lai, C.P. Lee, C.N. Liao, and Z.H. Wei," Oscillation spectrums and beat phenomenon of a water droplet driven by electrowetting," Applied Physics Letters, 2009, 94, 154102

國際替代計量

液滴共振混合

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