Numerically modeled dynamic response of perfect and leaky dielectric droplets in an electric field

Abstract

Summary form only given. A dielectric liquid droplet in an immiscible dielectric medium will deform when subjected to an external electric field. This effect is a component of the motion seen in electrically actuated droplets in a lab-on-a-chip setting, and is being studied in order to provide a basis for modeling electrowetting actuation behaviour. It is, however, a widely studied phenomenon in its own right, and can be employed in various emulsion technologies. The present work is a finite element analysis of both the perfect and leaky dielectric models, taking into account the time dependence of the deformation and the nonlinearity encountered when the deformation becomes large. In order to assess the accuracy of the model, comparisons are made with the classical small-deformation analytic results and with recent finite element results. The effects of the fluid properties and the applied field on the transient response and the resulting deformation are observed, and the transient response in particular is analyzed in order to provide a basis for dynamic control of the system. This could lead to a strategy for reliably controlling the behaviour of droplets under electrowetting actuation on a microfluidic chip.