有別於傳統使用機械式幫浦來驅動流體，微流體系統常常使用外加交流電場來驅動流體。本論文研究對稱形交流電極設計，所形成的微渦流可將流體中的懸浮粒子收集至電極表面停滯點上，此方法非常適合各種分子、蛋白質、或DNAs的傳送或聚集。
我們分別探討頻率、電壓、邊界條件等因素對微渦流生成和停滯點的影響，實驗發現在頻率100Hz、電壓2.8 Vpp時有最佳粒子聚集效率，從電壓與平均流速的關係證實該流動機制為交流電滲流(ACEO)。此外，經由特殊邊界條件的設計，近一步證實單純的ACEO流動機制便足以在電極上產生停滯點。同時，我們也使用FEMLAB軟體計算各種邊界條件下停滯點位置，得到和實驗數據一致的比較和分析結果。

In microfluidic systems, fluid is usually driven by an external AC electric field rather than a conventional mechanical pump. In this thesis, AC electrodes were designed to generate micro vortices for the assembly of suspended particles onto stagnation points on the electrodes. Such a design is useful for the transport and assembly of various molecules, proteins, and DNAs.
We studied the effects of AC frequencies, voltages, and boundary conditions on the formation of micro vortices and stagnation points. Experimental results demonstrated that the best efficiency of suspended particles assembly occurred at the frequency of 100Hz and the voltage of 2.8Vpp. From the relationship between the applied voltage and the average velocity, it was verified that the flow mechanism was the AC electroosmotic (ACEO) flow. In addition, our specific boundary conditions experiments revealed that pure ACEO flow could give rise to the observed stagnation points. The experimental data are consistent with the simulation results about the position of stagnation points by the FEMLAB software.

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