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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 10: Poster: Charged Soft Matter
CPP 10.3: Poster
Monday, March 14, 2011, 17:30–19:30, P2
Active swimming in self-generated ionic gradients — •Michael Hauber, Benedikt Sabass, and Udo Seifert — II Institut für Theoretische Physik, Universität Stuttgart, Germany
A thorough analytic understanding of phoresis in self-generated ionic gradients is still lacking. Therefore, we study here the behavior of a charged spherical particle, which emittes a charged solute with a fixed rate. The equations describing the electrical potential, the chemical potential, and the velocity field are solved through a perturbation theory for small surface charge density. The phoretic velocity of the particle is given as a closed analytical expression, obtained from the balance between electrostatic and hydrodynamic forces. It depends on the value κ a, where a is the radius of the particle and κ−1 is the Debye screening length. The limiting results of very small values of κ a (Debye-Hückel limit) and very large values (Smoluchowski limit) are derived. Further, we investigate the dependence of the particle speed on different ways of solute emission. We also take a look at the possibility of velocity reversion for varying surface charge potential.