Simulation studies on electrothermal fluid flow induced in a dielectrophoretic microelectrode system
Simulation studies on electrothermal fluid flow induced in a dielectrophoretic microelectrode system
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DOI：
10.1088/0960-1317/16/11/023
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发表时间：
2006-11-01
影响因子：
2.3
通讯作者：
Du, H.
中科院分区：
文献类型：
--
作者：
Chen, D. F.;Du, H.
用于基于介电电泳（DEP）的微器件中的粒子操纵的非均匀AC电场不仅在粒子上产生力，而且由于局部加热而通过在电导率和介电常数中产生梯度而在液体中产生体积力。作用在液体上的力引起流体运动，这被称为湍流。本文对介电泳微电极阵列上的电热诱导流体流动进行了数值研究。通过耦合电、热、力学方程数值求解流体运动。一些参数，包括频率，电极结构，导电性的流体和外部加热影响的流体流动模式进行了研究。研究了颗粒在湍流作用下的行为。当颗粒尺寸减小到亚微米尺度时，由微流体流动引起的颗粒上的粘性拖曳力变得明显。在某些情况下，拖曳力可以与DEP力具有相同的数量级或比DEP力大得多。在微流体流动的作用下，小颗粒可能表现出与普通DEP环境中不同的运动。这些结果为在正常DEP条件下使用交流电场操纵纳米颗粒提供了重要建议。
The inhomogeneous ac electric fields used for particle manipulation in dielectrophoresis(DEP)-based microdevices not only produce forces on the particle, but also generate volume forces in the liquid by producing gradients in conductivity and permittivity due to local heating. The forces on the liquid give rise to fluid motion, which is referred to as electrothermal flow. This paper presents a numerical study on the electrothermally induced fluid flow on the dielectrophoretic microelectrode array. The fluid movement is numerically solved by coupling electrical, thermal and mechanical equations. A number of parameters including frequency, electrode structure, conductivity of the fluid and external heating that influence the fluid flow patterns are investigated. Particle behavior under the effects of electrothermal flow is studied. The viscous drag force on the particles arising from the electrothermal fluid flow becomes apparent as the particle size is reduced to the sub-micrometer scale. In certain circumstances, the drag force may be of the same order as or much greater than the DEP force. Under the effect of the electrothermal fluid flow, small particles may exhibit movements differing from that in the common DEP environment. These results provide significant suggestions for the manipulation of nanoparticles using ac electric fields under the normal DEP conditions.