Microrheology & fluctuations

microrheology of and fluctuations in passive and active colloidal matter

In microrheology, the local rheological properties such as viscoelasticity of a complex fluid are inferred from the free (thermal) or forced motion of probe particles. The probes can be either embedded colloidal particles or tagged organelles and molecules existing in the biological material. The study of the deformation or flow of biological materials at small length scales has been termed biomicrorheology and deemed a frontier in microrheology. Indeed, particle-tracking microrheology has been widely used in experimental measurements to characterize the rheological properties inside living cells.

Left: diffusion of a free tracer; center: forced translational microrheology; right: rotational microrheology.



  1. Forced microrheology of active colloids
    Zhiwei Peng, and John F. Brady
    Journal of Rheology, Sep 2022
  2. Trapped-particle microrheology of active suspensions
    Zhiwei Peng, and John F. Brady
    The Journal of Chemical Physics, Sep 2022