Abstract

We consider a new type of active systems made of two types of colloidal particles each in contact with a thermostat but at different temperatures. We analyze the stability conditions of either uniformly mixed or phase segregated steady states consisting of phases enriched with each type of particles.

We show that in sufficiently dilute mixtures, the system can be described by a non-equilibrium equivalent of the second virial approximation by neglecting three body and higher order collisions. In this approximation, we define non-equilibrium “chemical potentials” whose gradients govern diffusion fluxes and a non-equilibrium “osmotic pressure”, which governs the mechanical stability of the interface.

This model could be used to describe mixtures of bacteria and passive colloidal particles but it could also be related to the compartmentalization of the cell nucleus.