Dynamics and interactions of Quincke roller clusters: From orbits and flips to excited states

Abstract

Active matter systems may be characterized by the conversion of energy into active motion, e.g., the self-propulsion of microorganisms. Artificial active colloids form models that exhibit essential properties of more complex biological systems but are amenable to laboratory experiments. While most experimental models consist of spheres, active particles of different shapes are less understood. Furthermore, interactions between these anisotropic active colloids are even less explored. Here, we investigate the motion of active colloidal clusters and the interactions between them. We focus on self-assembled dumbbells and trimers powered by an external dc electric field. For dumbbells, we observe an activity-dependent behavior of spinning, circular, and orbital motions. Moreover, collisions between dumbbells lead to the hierarchical self-assembly of tetramers and hexamers, both of which form rotational excited states. On the other hand, trimers exhibit flipping motion that leads to trajectories reminiscent of a honeycomb lattice.

On the absence of collective motion in a bulk suspension of spontaneously rotating dielectric particles

“…The latter is particularly suitable for studying suspensions of non-spherical particles, such as spheroids 72 or helices. 52 Finally, our simulations could be extended to include wall effects and reproduce recent experiments on magnetic control of Quincke rollers, 73 dynamics of Quincke dimers and trimers, 74 and pear-shaped Quincke rollers. 75…”