Dresden 2017 – wissenschaftliches Programm

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 62: Fluids and Interfaces III

CPP 62.12: Vortrag

Donnerstag, 23. März 2017, 18:00–18:15, ZEU 255

Jumping drops on superhydrophobic surfaces: controlling energy transfer by timed electric actuation — Zhantao Wang, •Dirk van den Ende, Arjen Pit, Rudy Lagraauw, Daniel Wijnperle, and Frieder Mugele — Univ. of Twente, Enschede, The Netherlands

Aqueous sessile drops are launched from a superhydrophobic surface by electric actuation in an electrowetting configuration with voltage pulses of variable duration. We show that the jump height, i.e. the amount of energy that is transferred from surface energy to the translational degree of freedom, depends not only on the applied voltage but also in a periodic manner on the duration of the actuation pulse. The jump height for a pulse of optimized duration is almost twice as high as the one obtained upon suddenly turning off the voltage after equilibrating the drop under voltage. Representing the drop as a simple oscillator, we show that optimum pulse duration is related to the eigenfrequency of the drop. From a general perspective, our experiments illustrate a generic concept to manipulate drops on functionalized surfaces by tuning the duration of actuation stimuli to the intrinsic dynamics of the drops such that they can be positioned in a controlled manner in different non-equilibrium configurations.