Colloidal diffusion in confined geometries

Colloidal dispersions in confined geometries exhibit rich diffusive dynamics governed by an interplay between particle-particle and particle-wall interactions. This perspective reviews recent selected computational and experimental studies on diffusion of dense liquid-like dispersions in spatial confinement, with an emphasis on general physical concepts rather than system-specific details. The common thread is to analyse colloidal diffusion in confined geometries in terms of the local density experienced by the colloidal particles, viz. at the level of anisotropic pair densities, which have recently become experimentally accessible.