title: Electrically tunable wetting defects characterized by a simple capillary force sensor.
abstract: We present a concept of a wetting defect of continuously variable strength based on electrowetting, along with a capillary force sensor adapted for the characterization of macroscopically heterogeneous surfaces. Patterned electrodes submerged under an insulating layer are used to generate potential wells for drops of electrically conductive liquids on the solid surface, with a well depth that scales with the diameter of the drop and square of the applied alternating (AC) voltage. We characterize the strength of the electrowetting trap and the hysteretic motion of the drop along the surface, using a simple force sensor based on optical imaging of a thin bendable capillary. A force resolution of approximately 0.1 μN is achieved.
authors.affiliation: Physics of Complex Fluids and MESA+ Institute for Nanotechnology, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands.
authors.forename: Dieter
authors.initials: D
authors.lastname: 't Mannetje
authors.forename: Arun
authors.initials: A
authors.lastname: Banpurkar
authors.forename: Helmer
authors.initials: H
authors.lastname: Koppelman
authors.forename: Michel H G
authors.initials: MH
authors.lastname: Duits
authors.forename: Dirk
authors.initials: D
authors.lastname: van den Ende
authors.forename: Frieder
authors.initials: F
authors.lastname: Mugele
mesh_terms: D004560:Electricity; D004566:Electrodes; D010316:Particle Size; D013499:Surface Properties; D017155:Wettability