Abstract

Chemically-active droplets have become a truly canonical example  of active colloids that self-propel in microfluidic systems. Yet they remain fascinatingly simple, often being as simple as oil droplets immersed in an aqueous solution saturated in surfactants. Such self-solubilising droplets self-propel spontaneously as a result of the non-linear transport of surfactant molecules and micellar compounds by the interfacial flows induced at their surface by gradients of such species. Many recent experiments have reported the intriguing individual behaviour of these droplets and the onset of propulsion is now relatively well understood conceptually and modelled. Yet, almost all modeling considerations of such fascinating systems focus exclusively on the case of an isolated self-propelled droplet in an unbounded and quiescent fluid. In this presentation, I will review some of the most recent advances regarding these swimmers and how we can go beyond that simple canonical setting to understand these droplets and their interactions, with neighbors or with nearby boundaries.