Electrowetting Induced Droplet Generation in T-Junctions

Abstract

In the current study, droplet generation in a T-junction fluidic channel device was studied through using electrowetting actuation with the consideration of different droplet forming regimes. For this purpose, the finite element method (FEM) was used to solve the unsteady Naiver-Stokes equation. In addition, the level set method was applied to capture the interface between two phases. It was shown that there was a good agreement between obtained data and other work during the process of droplet generation in the absence of electrowetting actuation which results in decrease in the size of droplet with increasing the velocity ratios. In shearing regime, the effectiveness of electrowetting on the droplet generation frequency as well as droplet size is visible in a T-junction fluidic channel since after applying voltages, specified with non-dimensional electrowetting numbers of ?=0.5 and 1.2, dispersed phase is pulled out into the oil phase. In fact, with applying the voltage on the top wall, the droplet breakup time was decreased and smaller droplets were produced. Finally, different important parameters such as pressure difference across the interface as well as Shear Stress exerted from the continuous phase shear stress were examined in a detail.

An easy droplet-generation method using an inserted glass capillary into a microchannel

“…Droplet generation methods can be divided into active and passive categories based on the exerting forces (Chong et al 2016). Active approaches mainly employ external forces to generate droplets, such as electric, magnetic, and sound fields (Merdasi et al 2021;Al-Hetlani et al 2019;Han et al 2021). Passive approaches mainly design different microchannel structures and employ extrusion or shearing forces of the continuous phase to destabilize and break the interface between the two-phase fluids, resulting in droplet (or bubble) formation (Chen et al 2021).…”