可設計形狀之金屬塗層Janus粒子感應電荷電泳之研究

Abstract

從先前的文獻中可以得知，膠體粒子的對稱性與幾何形狀會顯著的影響其在流體中的電動力學運動行為。而近幾年來，Janus粒子在微流體領域中的研究日增月益，其在交流電場下，垂直電場方向的特殊非線性的感應電荷電泳(ICEP)運動現象也受到關注。在本篇論文中，特別針對Janus粒子幾何尺度上的變化對於其感應電荷電泳運動速度的影響進行探討，透過有限元素法之數值模擬將三種物理模型耦合並符合Poisson-Nernst-Planck equations與 Navier-Stokes equations，在施加電場下，形成由誘導電雙層受到電場響應後驅動流體之感應電荷電滲流系統模型。而我們藉由建構此系統模型並分析Janus粒子在幾何形狀上的差異對於其感應電荷電泳速度之影響，透過與先前實驗數據比較，並探討金屬塗層端對於其運動的依賴性與在不同電場取向下其感應電荷電泳運動之影響，最後提出一種類似Janus鋸齒結構之微流泵，其在交流電場下具有同方向輸送流體之功能。

We can know that the symmetry and shape of colloidal particles will significantly affect their electrokinetic phenomena in fluid from previous literatures. Recently, there are more research of Janus particles applied in microfluidics, and the nonlinear electrokinetic phenomena of ICEP motion in Janus particles in directions perpendicular to a uniform ac field has also been concerned. In this study, we investigate the effects of the different shapes of Janus particles which affect their ICEP motion. We solved numerically coupled three physic models and Poisson-Nernst-Planck equations and Navier-Stokes equations with the numerical simulation of finite element method to build the ICEO system of induced EDL responded by applied field driving fluid. We analyze how the geometric shapes of Janus particles affect their ICEP motion through comparison with previous experimental data, and consider the dominant effect of metal coating sides of Janus particles affecting their motion. In the end, we report a Janus sawtooth shape structure microfluidic electrokinetic pump which can drive flows with same direction in AC electric field.