Electro-Elastic Wetting: A Method to Migrate and Deform Droplets

A new wetting mechanism, termed electro-elastic wetting, and methods to exploit it for droplet manipulation are proposed and demonstrated. The system consists of a droplet of dielectric liquid, an elastic and conductive membrane as its shell, and an electrode-dielectric composite as its substrate. Activation is by an electric field applied between the membrane and the substrate. The equilibrium shape of the droplet is determined by the balance of membrane tension and electrostatic attraction. It is shown that the contact angle of the droplet is governed by a modified Young-Lipmann Equation. It is then demonstrated that it is possible to transport the droplet along a controlled direction, as well as to actively tune its shape, topography, and position by manipulating the spatial distribution of the electrical force.