Emergence of macroscopic directed motion in populations of motile colloids

  title={Emergence of macroscopic directed motion in populations of motile colloids},
  author={Antoine Bricard and Jean-Baptiste Caussin and Nicolas Desreumaux and Olivier Dauchot and Denis Bartolo},
From the formation of animal flocks to the emergence of coordinated motion in bacterial swarms, populations of motile organisms at all scales display coherent collective motion. This consistent behaviour strongly contrasts with the difference in communication abilities between the individuals. On the basis of this universal feature, it has been proposed that alignment rules at the individual level could solely account for the emergence of unidirectional motion at the group level. This… 
Formation of stable and responsive collective states in suspensions of active colloids
Experimental evidence is provided by investigating the stability of swirls formed by light-responsive active colloids which adjust their individual motion to positions and orientations of neighbours to support the idea of system-independent organisation principles of collective states.
Emergent vortices in populations of colloidal rollers
It is demonstrated that the emergent-vortex structure lives on the verge of a phase separation, and a continuum theory is established to lay out a strong foundation for the description of vortical collective motion in a broad class of motile populations constrained by geometrical boundaries.
A phase diagram for bacterial swarming
Genetic mutations are exploited to experimentally characterize how distinct swarming phases of Bacillus subtilis emerge as a function of the shape and density of these bacteria, suggesting that bacteria have adapted their physical properties to optimize the principle functions assumed for swarming.
Emergent swarming states in active particles system with opposite anisotropic interactions
From the organization of animal flocks to the emergence of swarming behaviors in bacterial suspension, populations of motile organisms at all scales display coherent collective motion. Recent studies
Directed collective motion of bacteria under channel confinement
Dense suspensions of swimming bacteria are known to exhibit collective behaviour arising from the interplay of steric and hydrodynamic interactions. Unconfined suspensions exhibit transient,
Arrested-motility states in populations of shape-anisotropic active Janus particles.
The emergence of large-scale collective phenomena from simple interactions between individual units is a hallmark of active matter systems. Active colloids with alignment-dominated interparticle
Swimming Suppresses Correlations in Dilute Suspensions of Pusher Microorganisms
Active matter exhibits various forms of non-equilibrium states in the absence of external forcing, including macroscopic steady-state currents. Such states are often too complex to be modelled from
Applied physics: On a roll
This work demonstrates that genuine physical interactions at the individual level are sufficient to set homogeneous active populations into stable directed motion and could be used to model natural collective motion and to design new self-organized materials and swarming microrobots.
Nonequilibrium emergent interactions between run-and-tumble random walkers
Nonequilibrium statistical physics involves the study of many-particle systems that break time reversibility—also known as detailed balance—at some scale. For states in thermal equilibrium, which
Gliding filament system giving both global orientational order and clusters in collective motion.
It is demonstrated that not only alignment but also crossing of two filaments is essential to produce an effective multiple-particle interaction and the global order and the chiral symmetry breaking of a microtubule motion which causes a rotation of global alignment is described.


Polar patterns of driven filaments
A minimal polar-pattern-forming system that consists of highly concentrated actin filaments propelled by immobilized molecular motors in a planar geometry is demonstrated, identifying weak and local alignment interactions to be essential for the observed formation of patterns and their dynamics.
Large-scale vortex lattice emerging from collectively moving microtubules
This study reports experiments in which microtubules are propelled by surface-bound dyneins, providing evidence for the existence of previously unsuspected universality classes of collective motion phenomena.
Collective motion and density fluctuations in bacterial colonies
This work reports simultaneous measurements of the positions, velocities, and orientations as a function of time for up to a thousand wild-type Bacillus subtilis bacteria in a colony, demonstrating that bacteria are an excellent system to study the general phenomenon of collective motion.
Living Crystals of Light-Activated Colloidal Surfers
A form of self-organization from nonequilibrium driving forces in a suspension of synthetic photoactivated colloidal particles is demonstrated, which leads to two-dimensional "living crystals," which form, break, explode, and re-form elsewhere.
Hydrodynamics of soft active matter
This review summarizes theoretical progress in the field of active matter, placing it in the context of recent experiments, and highlights the experimental relevance of various semimicroscopic derivations of the continuum theory for describing bacterial swarms and suspensions, the cytoskeleton of living cells, and vibrated granular material.
Hydrodynamics of confined active fluids.
This work demonstrates that hydrodynamic interactions between confined swimmers depend solely on their shape and are independent of their specific swimming mechanism, and quantifies the consequences of these microscopic interaction rules on the large-scale hydrodynamics of isotropic populations.
Collective motion of self-propelled particles interacting without cohesion.
The onset of collective motion in Vicsek-style self-propelled particle models in two and three space dimensions is studied in detail and shown to be discontinuous (first-order-like), and the properties of the ordered, collectively moving phase are investigated.
Hydrodynamic fluctuations in confined emulsions
When an ensemble of particles interact hydrodynamically, they generically display large-scale transient structures such as swirls in sedimenting particles [1], or colloidal strings in sheared
Collective motion of binary self-propelled particle mixtures.
  • A. Menzel
  • Physics
    Physical review. E, Statistical, nonlinear, and soft matter physics
  • 2012
The interaction between the two species reduces the threshold density for the onset of collective motion of each species, but this interaction also reduces the spatial organization in the stripelike flocks of collectively moving particles.
Confinement stabilizes a bacterial suspension into a spiral vortex.
The competition between radial confinement, self-propulsion, steric interactions, and hydrodynamics robustly induces an intriguing steady single-vortex state, in which cells align in inward spiraling patterns accompanied by a thin counterrotating boundary layer.