Motion of generated dumbbell-shaped satellite droplets during liquid dielectrophoresis

Nampoothiri, KN and Sen, P (2021) Motion of generated dumbbell-shaped satellite droplets during liquid dielectrophoresis. In: Journal of Micromechanics and Microengineering, 31 (9).

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Abstract

Actuation of sub-millimeter sized droplets has important implications in heat transfer, microfluidics, and self-cleaning surfaces. Here, we report the motion of satellite droplets generated around a primary droplet actuated using liquid dielectrophoresis (L-DEP). Satellite droplets spanning the electrode gap grow due to the electric field induced enhanced merging of droplets. These satellite droplets attain a dumbbell shape due to the applied field. Interestingly, satellite droplets follow the primary drop interface maintaining a constant gap between themselves and the primary drop. The motion of satellite droplets was captured using high-speed imaging, and the role of temperature gradient was verified by measuring temperature distribution using an IR camera. Through observations and simulations, we qualitatively believe that this behavior arises from (a) repulsive electrostatic and temperature gradient forces; and (b) attractive vapor concentration gradient forces. Simulations were used to estimate the direction of individual forces. Interfacial charges from the applied electric field give rise to the electrostatic repulsion. During L-DEP, the primary droplet heats due to induced current. Thermal conduction through the substrate sets up a temperate gradient, which adds to the repulsion forces between the droplets. Evaporation of the primary droplet leads to the vapor concentration gradient, responsible for the attraction force between the droplets. © 2021 IOP Publishing Ltd.

Item Type:	Journal Article
Publication:	Journal of Micromechanics and Microengineering
Publisher:	IOP Publishing Ltd
Additional Information:	The copyright for this article belongs to IOP Publishing Ltd
Keywords:	Electric fields; Electrophoresis; Heat transfer; Satellites; Thermal gradients, Electric field induced; Electrostatic repulsion; High speed imaging; Interfacial charge; Liquid dielectrophoresis; Satellite droplets; Thermal conduction; Vapor concentrations, Drop breakup
Department/Centre:	Division of Interdisciplinary Sciences > Centre for Nano Science and Engineering
Date Deposited:	03 Dec 2021 07:15
Last Modified:	03 Dec 2021 07:15
URI:	http://eprints.iisc.ac.in/id/eprint/70147

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