Electric field-induced pinch-off of a compound droplet in Poiseuille flow

Abstract

We address the pinch-off dynamics of a compound droplet that is suspended in a carrier fluid in a parallel plate microchannel. The droplet is subjected to a transverse electric field in the presence of an imposed pressure-driven flow. When a concentric compound droplet migrates in a pressure driven flow, the inner droplet deviates from the concentric position and forms an eccentric configuration that finally leads to the pinch-off of the outer shell. Our results reveal that the temporal evolution of droplet eccentricity as well as the kinetics of the thinning of the outer droplet is markedly influenced by the strength of the electric field as well as the electric properties of the fluids. We also bring out the conversion of different modes of droplet pinch-off, such as the equatorial cap breakup or the equatorial hole-puncture mode, by altering the electric field strength and electrical properties of the fluids. We also identify the relevant pointers that dictate the pinch-off time as well as the location of the pinch-off. This, in turn, opens up novel means of modulating the morphology of double emulsion in a confined channel by applying an electric field