Dresden 2017 – scientific programme

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BP: Fachverband Biologische Physik

BP 12: Microswimmers I (Joint Session DY/BP)

BP 12.7: Invited Talk

Tuesday, March 21, 2017, 11:30–12:00, HÜL 186

Emergent structures in actuated magnetic and active colloidal suspensions — •Ignacio Pagonabarraga — University of Barcelona, Barcelona, Spain

Actuated and autocatalytic colloids constitute systems that are intrisically out of equilibrium. As a result fo their dynamic interactions, they can show a rich variety of self assembly scenarios. The observed self assembled structures make these systems very sensitive to external forcing, hence making actuated and active matter a fertile ground to explore and develop mechanically tunable materials.

I will analyze the basic physical mechanisms that control the collective behavior of two kinds of colloidal particles that move in a liquid medium. Confined magnetic colloids can rectify their motion when actuated with a rotating magnetic field, acting as a hydrodynamic conveyor belt. Self assembled chains of rotors propel faster than individual ones, reaching a saturation speed at distances where induced-flow additivity vanishes. The development of Janus colloids has opened the possibility to create synthetic microrobots that can move due to the chemical reacions they catalyze on their heterogeneous surfaces. The motion of chemically powered colloids is intricate because of the interplay between chemical and hydrodynamic interactions. These dynamic interactions have a strong impact in the collective behavior of these suspensions. I will describe the analogies and specificities in the hydrodynamic coupling that characterize these two types of systems.