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CPP: Chemische Physik und Polymerphysik

CPP 20: SYMPOSIUM Microfluidics I: Boundary conditions, manipulation, and transport

CPP 20.4: Vortrag

Donnerstag, 30. März 2006, 10:30–10:45, ZEU 160

Factors affecting the determination of hydrodynamic slip by using the colloidal probe technique — •Elmar Bonaccurso, Benoit Semin, and Svetlana Guryianova — Max-Planck-Institut für Polymerforschung

Recently, new insight has been gained in describing the boundary condition for the flow of a liquid on a solid, especially in microfluidic devices and other types of highly confined geometries. There is experimental evidence that the no-slip boundary condition, as usually applied for modeling macroscopic fluid flows, may break down at the nanometer scale, and that it might be replaced by a partial-slip boundary condition. One of the experimental techniques able to reveal the occurrence of slip at this scale is the colloidal probe technique: a micron-sized, spherical bead is attached to an atomic force microscope cantilever and pushed towards a solid, flat surface in the liquid which is tested. By measuring the interaction between sphere and surface, one can indirectly infer the velocity of the liquid at the boundary. Here we present a number of factors which affect such a measurement, thus allowing to determine/exclude the presence of slip and eventually helping to quantify it.