Regensburg 2010 – scientific programme

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 26: Micro and Nanofluidics I

CPP 26.6: Talk

Wednesday, March 24, 2010, 15:15–15:30, H39

Flow of microliter and submicroliter droplets on inclined surfaces — •David Magerl, Volker Körstgens, and Peter Müller-Buschbaum — TU München, Physik-Department LS E13, James-Franck-Str. 1, 85747 Garching (Germany)

Theory predicts that very small droplets under an external body force show a different behavior than larger drops. The velocity of large drops is dominated by dissipation in the volume, that of small droplets by friction at the substrate. The aim of our work is to find experimental proof to this interesting phenomenon. Therefore we investigate the gravity-driven movement of microliter and submicroliter droplets on inclined surfaces. We measure the velocity of these small droplets as a function of their size. In these experiments both, the surface treatment and the liquid of the droplets have been varied. The experiments are conducted in a saturated atmosphere of the according liquid. First, the droplet size on a horizontally oriented surface is measured by optical means, then the surface is tilted and the velocity of the flowing droplet is determined by the optical investigation of the droplet movement on the incline. We present experiments with toluene and water on silicon surfaces of different surface energies and compare the results to the theoretical simulations.