Numerical studies of electrically induced pattern formation by coupling liquid dielectrophoresis and two‐phase flow
Numerical studies of electrically induced pattern formation by coupling liquid dielectrophoresis and two‐phase flow
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DOI：
10.1002/elps.201100036
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发表时间：
2011-09
期刊：
影响因子：
2.9
通讯作者：
Hongmiao Tian;J. Shao;Yucheng Ding;Xin Li;Xiangming Li
中科院分区：
文献类型：
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作者：
Hongmiao Tian;J. Shao;Yucheng Ding;Xin Li;Xiangming Li
电诱导图案化工艺作为一种用于制造各种微米或纳米系统的新型微米或纳米结构方法，通常通过向电极对施加电压来实现，该电极对由图案化或非图案化模板和由气隙平行分隔的聚合物涂覆基板组成，然后对流体和介电聚合物进行光固化或热固化。迄今为止，为表征该图案化过程而进行的分析是基于受静电感应液压扰动的热不稳定薄膜的线性热力学。为了数学简单起见，这些分析仅针对平面模板和具有无限平面面积的平面薄膜表面进行制定，展示了聚合物薄膜上初始图案生长的趋势，但无法可视化实际应用中实际模板在整个图案化过程中微米或纳米结构生长的动态演变。本文试图通过提出一种基于 L-DEP 和两相流理论耦合的图案化过程数值模拟方法，从液体介电电泳 (L-DEP) 的角度提供对该图案化过程的另一种见解。首先，对硅油中水滴与底部水的电聚结进行了数值分析，以根据已发表的实验观察结果来衡量所提出的数值方法的有效性。然后提供了更多的数值结果来显示一些工艺变量对这种图案化过程中聚合物微米或纳米结构演变的影响。
Electrically induced patterning process, as a novel micro‐ or nano‐structuring approach for fabrication of various micro‐ or nano‐systems, is usually implemented by applying a voltage to an electrode pair consisting of a patterned or non‐patterned template and a polymer‐coated substrate separated in parallel by an air gap, followed by photo‐ or thermo‐curing of the fluidic and dielectric polymer. The analyses performed so far to characterize this patterning process have been based on linear thermodynamics for a thermally instable thin film perturbed by an electrostatically induced hydraulic pressure. For mathematical simplicity, these analyses were formulated only for a flat template and a flat film surface with infinite planar area, demonstrating the tendency of initial pattern growth on the polymer film, but being unable to visualize the dynamic evolution of micro‐ or nano‐structure growth throughout the patterning process for a real‐life template in practical applications. This paper attempts to provide another insight into this patterning process from a viewpoint of liquid dielectrophoresis (L‐DEP), by presenting an approach for numerical simulation of the patterning process based on a coupling of L‐DEP and two‐phase flow theories. First, a numerical analysis has been made for the electrocoalescence of a water droplet with bottom water in silicone oil to benchmark effectiveness of the proposed numerical approach against published experimental observations. More numerical results have then been provided to show effects of some process variables on the evolution of the polymer micro‐ or nano‐structures for this patterning process.