Group formation and cohesion of active particles with visual perception–dependent motility

See allHide authors and affiliations

Science  05 Apr 2019:
Vol. 364, Issue 6435, pp. 70-74
DOI: 10.1126/science.aau5347

You are currently viewing the abstract.

View Full Text

Log in to view the full text

Log in through your institution

Log in through your institution

Seeing whom you interact with

Schools of fish and flocks of birds are familiar examples of biological active matter. The motion of individuals is guided by the collective, but without obvious neighbor-to-neighbor interactions. This behavior can be designed into synthetic particles with the right shape or surface properties. Lavergne et al. made Janus particles that become active upon light irradiation, but only when they can “see” their neighbors. This property led to the formation of groups of particles that flock together in particular ways without specific pairwise or flow-generated interactions.

Science, this issue p. 70


Group formation in living systems typically results from a delicate balance of repulsive, aligning, and attractive interactions. We found that a mere motility change of the individuals in response to the visual perception of their peers induces group formation and cohesion. We tested this principle in a real system of active particles whose motilities are controlled by an external feedback loop. For narrow fields of view, individuals gathered into cohesive nonpolarized groups without requiring active reorientations. For wider fields of view, cohesion could be achieved by lowering the response threshold. We expect this motility-induced cohesion mechanism to be relevant not only for the self-organization of living systems, but also for the design of robust and scalable autonomous systems.

View Full Text