Berlin 2008 – wissenschaftliches Programm
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 22: POSTERS Micro- and Nanofluidics
CPP 22.16: Poster
Mittwoch, 27. Februar 2008, 16:00–18:30, Poster A
Colloids dragged through a polymer solution — •Christof Gutsche1, Friedrich Kremer1, Matthias Krüger2, Markus Rauscher2, Rudolf Weeber3, and Jens Harting3 — 1Institut für Experimentalphysik I, Universität Leipzig — 2Max-Planck-Institut für Metallforschung, Stuttgart and Institut für Theoretische und Angewandte Physik, Universität Stuttgart — 3Institut für Computerphysik, Universität Stuttgart
We present micro-rheological measurements of the drag force on colloids pulled through a solution of lambda-DNA [1] (used here as a monodisperse model polymer) with an optical tweezer [2,3]. The experiments show a drag force which is larger than expected from the Stokes formula and the independently measured viscosity of the DNA solution. We attribute this to the accumulation of DNA in front of the colloid and the reduced DNA density behind the colloid. This hypothesis is corroborated by a simple drift-diffusion model for the DNA molecules, which reproduces the experimental data surprisingly well, as well as by corresponding Brownian dynamics simulations.
[1] Gutsche C, Kremer F, Krüger M, Rauscher M, Weeber R, Harting J, arXiv:0709.4142 [2] Gutsche C, Keyser UF, Kegler K, et al. Phys. Rev. E 76 (3): 031403 (2007) [3] Gutsche C, Salomo M, Kim YW, et al. MICROFLUIDICS AND NANOFLUIDICS 2 (5): 381-386 (2006)