Over the past two decades, researchers have developed a broad range of self-propelled systems, typically millimetric or micrometric in size and operating in aqueous environments. These systems have attracted interest both for exploring collective behaviours in the field of active matter and for their potential in biomedical applications, such as targeted drug delivery. A common approach to achieving autonomous motion involves the release of a chemical species that alters the surrounding environment, triggering interfacial phenomena that drive movement. At fluid interfaces, propulsion is often governed by the Marangoni effect, whereas motion within the fluid bulk or near solid surfaces typically relies on diffusiophoresis or diffusioosmosis. In all cases, some form of symmetry breaking is essential to initiate motion. In this presentation, I will examine three chemically active self-propelled systems: a camphor disk, a droplet of dichloromethane, and a colloidal raft composed of a hematite core surrounded by silica colloids. Despite their apparent symmetry, all three exhibit spontaneous motion. The objective is to elucidate the physical mechanisms underlying this motion.
Accès Salle des séminaires FAST-LPTMS (Bât. 530, salle C.120, 1er)