We report on experiments of electrowetting on dielectric (EWOD) on functional fibers in air. Firstly, we investigate the evolution of drop contact angle θ with the applied voltage Vrms. θ(Vrms) relationship is compared to the theoretical Young–Dupre model and shows a good agreement at low voltage. However it appears that the saturation effect is different when compared to the EWOD response on a planar surface. We then study reversibility of the phenomenon to show that the drop recovers its initial shape when the voltage is switched off. Secondly, EWOD is used to modulate the maximal volume ΩM of a hanging drop. Results are compared to numerical simulations performed with Surface Evolver software. A good agreement is observed and it appears that ΩM increases linearly with Vrms. Finally, we present a proof of concept of a drop manipulation tool on fiber networks. This consists of an EWOD driven valve that is capable of regulating the drop traffic at a cross-junction between two fibers.
Soft Matter
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