Spreading of a dielectric droplet through an interfacial electric pressure

Abstract

A corona discharge-assisted technique for spreading of a gently deposited dielectric droplet into a uniform thin film over a dry isothermal conductive substrate is proposed. The surface charge was built up over the droplet interface through ion bombardment using a sharp emitter electrode. Interaction of the surface charge density and intense electric field generates an interfacial electrical pressure and leads to a uniform axisymmetric spreading of the droplet in the radial direction. It was shown that the droplet expansion process can be controlled through variation of the ion injection current and/or discharge exposure time. It is also demonstrated that the proposed technique can be analogous to the classical Stefan's squeezing liquid flow between two separated parallel discs. The dynamics of the film spreading owing to the corona discharge can be predicted through a simplified analytical model based on this analogy.