Discrete Electrostatic Charge Transfer by the Electrophoresis of a Charged Droplet in a Dielectric Liquid
Discrete Electrostatic Charge Transfer by the Electrophoresis of a Charged Droplet in a Dielectric Liquid
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DOI：
10.1021/la3014392
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发表时间：
2012-08-14
期刊：
影响因子：
3.9
通讯作者：
Kang, In Seok
中科院分区：
文献类型：
--
作者：
Im, Do Jin;Ahn, Myung Mo;Kang, In Seok
我们已经实验研究了带电电极表面上的水滴的静电充电，以解释详细的感应充电过程，并将其用于芯片实验室系统中的液滴位置检测。本文用高分辨率静电计和图象分析方法研究了液滴在两平面电极间的周期性弹跳运动。我们发现这个充电过程包括三个步骤。第一步是通过液滴的电荷在相对电极上感应电荷累积。这个感应过程发生在液滴接近电极时，它在静电计上产生感应电流信号。第二步是液滴在接触的瞬间通过累积的感应电荷放电。对于第二步，静电计上没有电荷转移检测。第三步是当液滴与电极接触时，将中和的液滴充电到一定的带电状态。第三步骤的电荷转移被检测为静电计的脉冲型信号。第二步和第三步同时发生，而且速度很快。我们已经发现，由带电液滴的移动产生的感应电流可以准确地用于测量液滴的电荷，并且还可以用于监测致动下液滴的位置。目前的研究结果的理解和测量的充电过程的影响进行了讨论。
We have experimentally investigated the electrostatic charging of a water droplet on an electrified electrode surface to explain the detailed inductive charging processes and use them for the detection of droplet position in a lab-on-a-chip system. The periodic bouncing motion of a droplet between two planar electrodes has been examined by using a high-resolution electrometer and an image analysis method. We have found that this charging process consists of three steps. The first step is inductive charge accumulation on the opposite electrode by the charge of a droplet. This induction process occurs while the droplet approaches the electrode, and it produces an induction current signal at the electrometer. The second step is the discharging of the droplet by the accumulated induced charge at the moment of contact. For this second step, there is no charge-transfer detection at the electrometer. The third step is the charging of the neutralized droplet to a certain charged state while the droplet is in contact with the electrode. The charge transfer of the third step is detected as the pulse-type signal of an electrometer. The second and third steps occur simultaneously and rapidly. We have found that the induction current by the movement of a charged droplet can be accurately used to measure the charge of the droplet and can also be used to monitor the position of a droplet under actuation. The implications of the current findings for understanding and measuring the charging process are discussed.