Electrostatic transportation of water droplets on superhydrophobic surfaces

This article reports electrostatic transportation of water droplets on superhydrophobic alkylketene dimer (AKD) and Teflon AF/sup R/ surfaces. The actuation is based on electrostatic forces generated by metal electrodes placed underneath the surface. By switching the electrode voltages, the droplets moved stepwise along the electrode paths. The lowest voltage which resulted continuous movement was 124 VAC (rms) and the maximum speed was over 1 cm/s which shows great improvement with respect to previously reported electrostatic actuation of water droplets in open air [M. Washizu, "Electrostatic Actuation of Liquid Droplets for microreactor Applications", IEEE Trans. Ind. App. 34, 4 (1998), pp. 732-737].