Microrheology of Soft matter

Soft matter such as liquid crystals, polymer solutions and colloidal dispersions are complex fluids that exhibit viscoelasticity. Their macroscopic mechanical properties have been studied intensively in the field of rheology. Recently, the structures and dynamics of soft matter at micro- and nanoscale have attracted considerable attention from researchers. The study of microrheology, which deals with the mechanical properties of soft matter at the mesoscopic scale, has made remarkable progress owing to theoretical and technical developments. In this review, we present the basic methods of microrheology and their practical applications to soft matter. We also stress the importance of these methods for understanding fundamental physical problems in nonequilibrium systems at the mesoscopic scale.