Regensburg 2016 – scientific programme
Parts | Days | Selection | Search | Updates | Downloads | Help
CPP: Fachverband Chemische Physik und Polymerphysik
CPP 12: Poster: Colloids and Complex Fluids
CPP 12.2: Poster
Monday, March 7, 2016, 18:15–21:00, Poster B2
Experimental study of Stokes Einstein relation for a colloidal particle in nonequilibrium viscoelastic media — •Johannes Berner1, Juan Ruben Gomez-Solano1, and Clemens Bechinger1,2 — 12. Physikalisches Institut, Universität Stuttgart, Germany — 2MPI for Intelligent Systems, Stuttgart, Germany
Viscoelastic fluids are of great importance in biological systems and in medical and industrial applications. Their flow properties have been extensively studied by bulk rheology [1] and more recently by microrheology [2] using embedded colloidal probes. For instance in passive microrheology the Stokes Einstein relation is used to determine such properties by measuring the thermal fluctuations of the particle position [3]. This is only valid provided that the fluid and the particle are in thermal equilibrium. However this assumption is not trivially satisfied, if the microstructure of the fluid is driven far from equilibrium, e.g. by inducing a local deformation by means of the particle [4, 5]. In this work, we investigate the validity of the Stokes Einstein relation for a colloidal particle driven by optical tweezers through several viscoelastic media. In particular we focus on dependence on the local strain and strain rate.
[1] Larson R G 1999 The Structure and Rheology of Complex Fluids (New York: Oxford University Press), [2] Squires T. M. and Mason T. G., Annu. Rev. Fluid Mech., 42 (2010) 413, [3] Mason T. G. and Weitz D. A., Phys. Rev. Lett., 74 (1995) 1250, [4] Gomez-Solano J. R. and Bechinger C., EPL, 108 (2014) 54008, [5] Gomez-Solano J. R. and Bechinger C., New J. Physics, 17 (2015) 103032