本研究是探討次微米粒子於交流介電泳(Dielectrophoresis, DEP)結合流動作用下的運動行為。而實驗所使用的介電泳晶片是由PDMS製成的微流道和城垛型電極兩部分組裝成的。實驗方法是將次微米聚苯乙烯粒子加入到我們所配製的電解質溶液內，藉由電解質溶液及粒子的介電性質來控制介電泳效應。實驗結果顯示出粒子會形成與純DEP完全不同的粒子聚集形態，而粒子聚集形態可根據流量、外加電場頻率及溶液導電度來決定。此外，我們也提出尺度分析來解釋實驗結果。利用DEP配合流動作用可在連續模式下提濃、分離及收集粒子，故對於如何操縱次微米粒子可提供新的範例。

The motion of submicron particles under the condition of simultaneous flow and ac dielectrophoresis (DEP) is investigated experimentally using a microfluidic approach. Experiments are conducted within a PDMS microchannel integrated with arrays of castellated microelectrodes. Submicron latex particles are suspended in an electrolyte aqueous solution. The response of dielectrophoretic particle motion to the change in dielectric properties is carried out using different electrolyte concentrations. Results show that particle aggregation patterns are different from those of conventional DEP. Various new patterns of particle aggregation are identified, depending on the flow rate, the frequency of an applied electric field and the electrolyte conductivity. A scaling analysis is devised to explain the effects at work in accordance with experimental observations. The study provides new strategies for manipulating submicron particles in a continuous manner.

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