Dresden 2003 – wissenschaftliches Programm

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CPP: Chemische Physik und Polymerphysik

CPP 8: Neue Methoden

CPP 8.2: Vortrag

Mittwoch, 26. März 2003, 17:15–17:30, ZEU/160

Self-excited dynamics of electrified capillary bridges — •Anke Klingner, Juergen Buehrle, Stephan Herminghaus, and Frieder Mugele — Universitaet Ulm, Abt. Angewandte Physik, Albert-Einstein-Allee 11, D-89081 Ulm

We analyzed the influence of electric fields on capillary hysteresis between two flat electrodes that are covered by a thin insulating layer. Depending on the separation and the voltage applied between the electrodes, a fixed amount of conductive liquid either forms a capillary bridge or two separate droplets. The contact angle of a bridge reduces with raising potential difference across the insulation by electrowetting. The attraction of separated droplets increases with field strength. We find that a voltage applied between the electrodes destabilizes both the bridge and the droplet states. For suitable combinations of the applied AC voltage and the plate separation, the liquid is found to oscillate periodically between the two states. We present a model based on the balance of interfacial and electrostatic energies in the system, which explains the experimental findings.