Activity-induced interactions and cooperation of artificial microswimmers in one-dimensional environments

Abstract

Cooperative motion in biological microswimmers is crucial for their survival as it facilitates adhesion to surfaces, formation of hierarchical colonies, efficient motion, and enhanced access to nutrients. Here, we confine synthetic, catalytic microswimmers along one-dimensional paths and demonstrate that they too show a variety of cooperative behaviours. We find that their speed increases with the number of swimmers, and that the activity induces a preferred distance between swimmers. Using a minimal model, we ascribe this behavior to an effective activity-induced potential that stems from a competition between chemical and hydrodynamic coupling. These interactions further induce active self-assembly into trains where swimmers move at a well-separated, stable distance with respect to each other, as well as compact chains that can elongate, break-up, become immobilized and remobilized. We identify the crucial role that environment morphology and swimmer directionality play on these highly dynamic chain behaviors. These activity-induced interactions open the door toward exploiting cooperation for increasing the efficiency of microswimmer motion, with temporal and spatial control, thereby enabling them to perform intricate tasks inside complex environments.

Synchronization in collectively moving inanimate and living active matter

“…2b) . 1,26 Along the resulting circular trajectory of the motorized ball the speed oscillates (Supp. Fig.…”

A simple catch: thermal fluctuations enable hydrodynamic trapping of microrollers by obstacles

“…The trapping of active particles has been studied in experiments [13][14][15][16]21] and simulations [12,54], for bacteria [16,20] and spherical [12-14, 21, 54] and rodshaped [12,13,15] artificial microswimmers. The hydrodynamic trapping as reported in these studies is manifested in the orbit of the swimmers around round obstacles and along ridges above a critical relative curvature.…”

“…For example, by using pillars of various sizes, approaching bacteria could be scattered at a particular angle [18], or for larger pillars, trapped in an orbit [16,20]. Similar trapping has been observed in artificial swimmers [13,14,21], and by using more complex geometries, more exotic behaviors, such as directional trapping can be achieved [15].…”

Role of cohesion in the flow of active particles through bottlenecks

“…5b inset). Secondly, it is known that hydrodynamic interactions can increase the particle mobility even at low Reynolds numbers, as soon as two or APs are close by [39][40][41][42] . A further observation is the appearance of convection-like eddies in the bottleneck in the experiment (Fig.…”