Berlin 2024 – scientific programme

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DY: Fachverband Dynamik und Statistische Physik

DY 32: Poster: Active Matter, Soft Matter, Fluids

DY 32.18: Poster

Wednesday, March 20, 2024, 15:00–18:00, Poster C

Spontaneous Symmetry Breaking in Microdroplets Filled with Heat Releasing Particles — •Akshay Kallikkunnath, Arthur Markus Anton, and Frank Cichos — Molecular Nanophotonics, Peter Debye Institute for Soft Matter Physics, Faculty of Physics and Earth System Sciences, Leipzig University, Linnéstraße 5, 04103 Leipzig, Germany

Self-propulsion of microscopic objects require symmetry breaking, which is often achieved by preparing geometrically asymmetric particles, e.g., Janus particles. Self-propulsion can, however, also be achieved with symmetric particles like droplets, where the symmetry is broken dynamically, e.g., by a chemical reaction that induces Marangoni fluxes at the interface to the surrounding medium. Here, we show the self-propulsion of water-in-oil microdroplets encapsulated with symmetric iron oxide particles upon widefield laser illumination. The heat released by the particles close to the boundary of the droplet induces strong Marangoni flows that reshape the distribution of particles inside the droplet. The dynamics of the particles and hydrodynamic flow fields also couple to other particles to create collective motion and cohesive behavior. Our results provide insight into complex collective behavior of micro-particles in confinements and provide new directions for future research in the engineering of such actively propelled micromachines.

Keywords: Microdroplets; Self-propulsion; Symmetry breaking; Marangoni; Micromachines