Berlin 2012 – scientific programme

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 28: Colloids and Complex Liquids I

CPP 28.9: Talk

Wednesday, March 28, 2012, 17:30–17:45, C 130

Active Brownian Motion in Complex Environments — •Ivo Buttinoni — Universität Stuttgart, Stuttgart, Germany

Active Brownian particles are capable of taking up energy from their environment and converting it into directed motion; examples range from chemotactic cells and bacteria to artificial microswimmers. We develop a novel species of microswimmers whose active motion is due to the local demixing of a critical binary liquid mixture and can be easily tuned by illumination. Illumination causes a local heating of the caps, which induces a local asymmetric demixing of the binary mixture leading to a spatial concentration gradient across the particle. Since the heating strength is controlled by the incident light intensity, the particle's self-diffusiophoretic motion can be easily controlled. As a first step towards more realistic conditions under which such microswimmers will be employed, we study, experimentally and with numerical simulations, their behavior in patterned surroundings that present complex spatial features where frequent encounters with obstacles become important[1]. The motion of such swimmers inside mobile obstacles, i.e., passive colloids, is probed as well, showing memory effects related to the characteristics of both the passive and the active particles.

[1] G. Volpe, I. Buttinoni, D. Vogt, H.J. Kümmerer, and C. Bechinger. Microswimmers in patterned environments. Soft Matter, (7):8810{8815, 2011.