Rheological microscopy: Local mechanical properties from microrheology

A one- and two-point micro-rheological measurements and theory was used to determine the rheological microstructure of depletion-induced layers surrounding a tracer particle in a semidilute polymer solution. Furthermore, it was shown how the collapse of conventional one-point microrheological measurements can be applied to extract bulk viscoelastic moduli, a quantity heretofore unabiguously accessible only to two-point measurements of such systems. Refinements, both theoretical and experimental, of the basic rheological microscopy method given may enable its extension to the study of more complex media.