Virtual walls for dielectric fluid manipulation through controllable charge deposition

Abstract Fluid transportation is a basic physical process in various engineering applications, and solid walls are most commonly used to confine fluid flows. Solid walls, however, have some disadvantages, including large pressure drops and plaguing by fouling. Here we experimentally demonstrate a method of controlling dielectric fluid flows on planar surfaces by virtual (not solid) walls through a spatially controlled charge deposition. Acting on the three-phase contact line, an electrically induced pressure has the same function as solid sidewalls. Dielectric fluids can be confined within designated areas, or flow directionally with the aid of contactless masks. Dielectric fluids can also move on planar surfaces by moving contactless masks. Due to the virtual wall effect of this novel method, an open channel can be developed to continuously transport fluids. The method may provide a new perspective to manipulating dielectric liquid flows and can be an alternative way of open fluidic devices.