Dynamic Clustering in Active Colloidal Suspensions with Chemical Signaling
Abstract
In this Letter, we explore experimentally the phase behavior of a dense active suspension of self-propelled colloids. In addition to a solidlike and gaslike phase observed for high and low densities, a novel cluster phase is reported at intermediate densities. This takes the form of a stationary assembly of dense aggregates—resulting from a permanent dynamical merging and separation of active colloids—whose average size grows with activity as a linear function of the self-propelling velocity. While different possible scenarios can be considered to account for these observations—such as a generic velocity weakening instability recently put forward—we show that the experimental results are reproduced mathematically by a chemotactic aggregation mechanism, originally introduced to account for bacterial aggregation and accounting here for diffusiophoretic chemical interaction between colloidal swimmers.
- Publication:
-
Physical Review Letters
- Pub Date:
- June 2012
- DOI:
- 10.1103/PhysRevLett.108.268303
- arXiv:
- arXiv:1202.6264
- Bibcode:
- 2012PhRvL.108z8303T
- Keywords:
-
- 82.70.Dd;
- 05.65.+b;
- 47.57.ef;
- Colloids;
- Self-organized systems;
- Sedimentation and migration;
- Condensed Matter - Soft Condensed Matter;
- Condensed Matter - Statistical Mechanics;
- Physics - Chemical Physics
- E-Print:
- supplementary video :http:// www-lpmcn.univ-lyon1.fr/~lbocquet/Movie-Theurkauff-SI.avi