Electric field induced surface profile change of liquid film on a periodically aligned electrode array

Abstract

We investigated changes in surface profile of a dielectric liquid film put on a periodically aligned electrode array by imposing a voltage between adjacent electrodes. It is found that the surface of liquid film can be undulated by the electric field according to the periodicity of electrode array, and it rises on between adjacent positive and negative electrodes, on the other hand, it goes down at the central region on each electrode. The averaged height difference of undulated surface is proportional to the square of the interface electric field. It is also found that the averaged height difference increases with the width L of electrode for L < 1600 μm, decreases with L for L > 1600 μm, if the distance between adjacent electrodes is maintained constant. The averaged height difference does not change if the strength of interface electric field is adjusted to be the same for various thicknesses of liquid films. The time evolution of the height difference is also investigated using samples with various kinetic viscosities. It is found that the needed time t1/2 for the surface height difference to reach the half of the equilibrium one is proportional to the kinetic viscosity of the sample. © 2010 The Society of Rheology, Japan.