Regensburg 2007 – wissenschaftliches Programm
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 24: Micro and Nano Fluidics II: Soft Objects in Flow + Slippage
CPP 24.10: Vortrag
Donnerstag, 29. März 2007, 12:15–12:30, H37
Boundary flow on superhydrophobic surfaces — •Audrey Steinberger1, Cecile Cottin-Bizonne2, and Elisabeth Charlaix2 — 1MPI for Dynamics and Self-Organization, Göttingen, Germany — 2Laboratoire de Physique de la Matière Condensée et Nanostructures -- Université Claude Bernard Lyon 1 and CNRS, Lyon, France
With the development of microfluidic systems it becomes important to control flows at small scales for systems characterized by a large surface to volume ratio. A slip hydrodynamic boundary condition can both increase the flow rate at a given pressure gradient, and reduce the hydrodynamic dispersion. Trapping gas in superhydrophobic surfaces has been suggested as a good way to obtain high and controlled slippage.
We have investigated the boundary flow of water-glycerol mixtures on superhydrophobic surfaces, using a dynamic Surface Force Apparatus. Firstly, we show that the entrapped bubbles confer elastic properties to superhydrophobic surfaces. Measuring those elastic properties allowed us to probe the meniscus shape of the bubbles. Secondly, we have shown that, contrary to conventional notions, microbubbles at the solid-liquid interface do not systematically lubricate the interface. Protruding microbubbles can strongly reduce the slippage instead. The control of the meniscus shape is thus a key point to control the slippage and has to be integrated into the conception of the design of microsystems.