Electric Field Induced Patterning of Thin Coatings on Fiber Surfaces

Abstract

We explore the electric field induced instabilities of a thin liquid film coated on a fiber surface. Thin liquid films on the curved surfaces spontaneously self-organize into interesting patterns such as a string of beads/droplets when the destabilizing radial curvature force dominate over the stabilizing in plane curvature. Application of an external electrostatic field in such a situation opens up the added possibility of fabricating ridge like structures issuing outward from the film surface when electric field dominates over the curvature forces. With the help of a general linear stability analysis and long-wave nonlinear simulations, the study uncovers the conditions under which the ridges and beads form on the fiber surface. In particular, we show that the ridges are favored morphologies when electric field is stronger because of higher film to air filling ratio in between the electrodes, higher applied voltage, and larger fiber radius. The beads and the ridges are found to coexist when the destabil...