Regensburg 2025 – scientific programme

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DY: Fachverband Dynamik und Statistische Physik

DY 36: Microswimmers and Microfluidics (joint session DY/BP/CPP)

DY 36.3: Talk

Thursday, March 20, 2025, 15:45–16:00, H37

Active particle steering in three dimensions — •Gordei Anchutkin and Frank Cichos — Molecular Nanophotonics Group, Peter Debye Institute for Soft Matter Physics, Leipzig University, Leipzig, Germany

Synthetic active particles serve as a model system that mimic the self-propulsion of living matter to explore fundamental aspects of non-equilibrium physics. Various collective phenomena of active agents have been studied, but mostly in the presence of hydrodynamic and physicochemical boundary effects. While theoretical works predict different collective dynamics in 3D, experimental investigations remain limited due the lack of experimental control over active swimmers in three dimensions.

Here we introduce three-dimensional control to the study of synthetic active matter. We demonstrate simultaneous control of thermophoretic microswimmers in 3D using single-particle tracking through digital holography and darkfield pattern tracking, with real-time wavefront shaping for steering. With the help of these experiments, we explore the interplay of thermophoretic propulsion, gravity, and optical forces for the active particles. By creating a three-dimensional active ensemble, we reveal how bulk interactions and boundary effects shape the collective behavior of active particles.

Keywords: 3D; boundary; collective dynamics; experimental control; microswimmers