Living crystals of light-activated colloidal surfers.
Spontaneous formation of colonies of bacteria or flocks of birds are examples of self-organization in active living matter. Here, we demonstrate a form of self-organization from nonequilibrium driving forces in a suspension of synthetic photoactivated colloidal particles. They lead to two-dimensional "living crystals," which form, break, explode, and re-form elsewhere. The dynamic assembly results from a competition between self-propulsion of particles and an attractive interaction induced respectively by osmotic and phoretic effects and activated by light. We measured a transition from normal to giant-number fluctuations. Our experiments are quantitatively described by simple numerical simulations. We show that the existence of the living crystals is intrinsically related to the out-of-equilibrium collisions of the self-propelled particles.
Department of Physics, New York University, 4 Washington Place, New York, NY 10003, USA. jp153@nyu.edu
Jeremie
J
Palacci
Stefano
S
Sacanna
Asher Preska
AP
Steinberg
David J
DJ
Pine
Paul M
PM
Chaikin