‘Fuelled’ motion: phoretic motility and collective behaviour of active colloids

Active , phoretic motion

Hydrodynamics determines collective motion and phase behavior of active colloids in quasi-two-dimensional confinement.

We study the collective motion of confined spherical microswimmers such as active colloids which we model by so-called squirmers. To simulate hydrodynamic flow fields including thermal noise, we use the method of multiparticle collision dynamics. We demonstrate that hydrodynamic near fields acting between squirmers as well as between squirmers and bounding walls crucially determine their collec...

Driven motion of colloids in active microrheology

In active microrheology, a strong external force is applied to a colloidal probe immersed in a complex fluid, so that among other quantities the nonlinear force-velocity relation can be measured. It provides information on the local viscoelastic properties of the complex fluid or soft solid. Generally, in dense fluids, the probe’s friction coefficient decreases strongly with increasing force [1...

Phoretic Interactions Generically Induce Dynamic Clusters and Wave Patterns in Active Colloids.

We introduce a representative minimal model for phoretically interacting active colloids. Combining kinetic theory, linear stability analyses, and a general relation between self-propulsion and phoretic interactions in autodiffusiophoretic and autothermophoretic Janus colloids collapses the parameter space from six to two dimensionless parameters: area fraction and Péclet number. This collapse ...

Collective motion dynamics of active solids and active crystals

We introduce a simple model of self-propelled particles connected by linear springs that describes a semi-rigid formation of active agents without explicit alignment rules. The model displays a discontinuous transition at a critical noise level, below which the group self-organizes into a collectively translating or rotating state. We identify a novel elasticity-based mechanism that cascades se...