A novel actuation method of transporting droplets by using electrical charging of droplet in a dielectric fluid
A novel actuation method of transporting droplets by using electrical charging of droplet in a dielectric fluid
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DOI：
10.1063/1.3122299
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发表时间：
2009-04-01
期刊：
影响因子：
3.2
通讯作者：
Kang, In Seok
中科院分区：
文献类型：
--
作者：
Jung, Yong-Mi;Kang, In Seok
我们评估了通过利用库仑力作用于浸没在介电流体中的导电液滴来操纵二维液滴的可行性。当悬浮在不相容流体中的液滴在直流电压下位于电极附近时，液滴可以通过直接接触、沿着导电路径的电荷转移或通过这两种机制来充电。这个过程被称为液滴带电(ECOD)。然后，这种带电液滴可以利用库仑力快速传输。我们通过施加电压序列实验演示了带电液滴的电驱动。带电液滴通过跟随电场信号的方向被二维激励。当微流控芯片移动时，液滴不会接触到表面。这一特性是非常有利的，因为微流控芯片衬底表面的处理变得更简单。为了验证在液滴微反应器中使用ECOD的可行性，还研究了两个带相反电荷的液滴的电聚并。当两个液滴由于库仑引力而靠近时，它们之间就形成了液桥。我们假设，如果外加电场弱于某一临界水平，当电荷通过这个液桥交换和重新分布时，两个液滴瞬间合并。
We evaluate the feasibility of manipulating droplets in two dimensions by exploiting Coulombic forces acting on conductive droplets immersed in a dielectric fluid. When a droplet suspended in an immiscible fluid is located near an electrode under a dc voltage, the droplet can be charged by direct contact, by charge transfer along an electrically conducting path, or by both mechanisms. This process is called electrical charging of droplet (ECOD). This charged droplet may then be transported rapidly by exploiting Coulombic forces. We experimentally demonstrate electrical actuation of a charged droplet by applying voltage sequences. A charged droplet is two dimensionally actuated by following the direction of the electrical field signal. The droplet does not contact the surface of the microfluidic chip when it moves. This characteristic is very advantageous because treatments of the substrate surfaces of microfluidic chip become simpler. In order to test the feasibility of using ECOD in a droplet-based microreactor, electrocoalescence of two oppositely charged droplets is also studied. When two droplets approach each other due to Coulombic attraction, a liquid bridge is formed between them. We postulate that if the applied electric field is weaker than a certain critical level, the two droplets coalesce instantaneously when the charges are exchanged and redistributed through this liquid bridge.