Conditions for the propulsion of a colloid surrounded by a mesoscale phase separation

Abstract

We study a two-dimensional model of an active isotropic colloid whose propulsion is linked to the interactions between solute particles of the bath. The colloid catalyzes a chemical reaction in its vicinity, that yields a local phase separation of solute particles. The density fluctuations of solute particles result in the enhanced diffusion of the colloid. Using numerical simulations, we thoroughly investigate the conditions under which activity occurs, and we establish a state diagram for the activity of the colloid as a function of the parameters of the model. We use the generated data to unravel a key observable that controls the existence and the intensity of activity: the filling fraction of the reaction area. Remarkably, we finally show that propulsion also occurs in three-dimensional geometries, which confirms the interest of this mechanism for experimental applications.

References in corpus (7)

• The hydrodynamics of swimming microorganisms
• Designing phoretic micro- and nano-swimmers
• Self-propulsion of pure water droplets by spontaneous Marangoni stress driven motion
• 'Fuelled' motion: phoretic motility and collective behaviour of active colloids
• Phoretic self-propulsion at finite Péclet numbers
• Active colloidal suspensions: Clustering and phase behavior
• Self-motility of an active particle induced by correlations in the surrounding solution