Modification of drop shape controlled by electrowetting

Wetting defects were created thanks to electrowetting: the effective surface tension between brine and an insulating solid is independently monitored, via an external electrical field, on two complementary areas (defect and background). This article describes the bicapacitor substrates that allow such a zone differentiation when connected to an adequate high-tension setup. Observations of the deformation of a drop on a stripe-shaped defect showed that it is possible to scan an appreciable range of wetting contrasts between the defect and the background with a unique sample. Theoretical calculations suggest an order of magnitude for electrostatic edge effects characteristic of these "virtual" wetting defects.