Quintero Juan Sebastian Marin, Majhy Butunath, Caesar Markus, Waghmare Prashant R
Interfacial Science and Surface Engineering Lab (iSSELab), Department of Mechanical Engineering, University of Alberta, Edmonton T6G 2R3, Canada.
Langmuir. 2023 Apr 11;39(14):4917-4923. doi: 10.1021/acs.langmuir.2c03194. Epub 2023 Mar 30.
Manipulating the coalescence of microdroplets has recently gained enormous attention in digital microfluidics and biological and chemical industries. Here, coalescence between two sessile droplets is induced by spreading them due to electrowetting. The electrocoalescence dynamics is investigated for a wide range of operating parameters such as electrowetting number, Ohnesorge number, driving frequency, and drop to surrounding medium viscosity ratio. Here, the characteristic time scale from the classical lubrication theory is modified with an additional driving and resisting force due to the electrostatic pressure force and liquid-liquid viscous dissipation, respectively. With the revised characteristic time scale, a universal bridge growth is shown between the two merging droplets following a 1/3 power law during early coalescence followed by a long-range linear variation. To ensure precise control on droplet coalescence, a geometric analysis is also performed to define the initial separation distance.
操控微滴的聚结最近在数字微流控以及生物和化学工业中受到了极大关注。在此，通过电润湿使两个固定液滴铺展从而诱导它们之间的聚结。针对诸如电润湿数、奥内佐格数、驱动频率以及液滴与周围介质的粘度比等广泛的操作参数，研究了电聚结动力学。在此，经典润滑理论中的特征时间尺度分别因静电力压力和液 - 液粘性耗散产生的额外驱动力和阻力而被修正。利用修正后的特征时间尺度，在早期聚结过程中，两个合并液滴之间呈现出遵循1/3幂律随后是长程线性变化的通用桥增长。为确保对液滴聚结的精确控制，还进行了几何分析以定义初始分离距离。
