Microrheology involves tracking the motion of dispersed tracer particles of known size by Dynamic Light Scattering (DLS) and determining the rheological properties of the sample using the Generalized Stokes-Einstein Relation. DLS Microrheology is a passive microrheology technique, whereby the colloidal probe particles only undergo thermal fluctuations in a system at thermodynamic equilibrium.

DLS Microrheology is applicable for the rheological characterization of low viscosity and weakly-structured complex fluids, such as dilute solutions of polymers and surfactants through to concentrated protein formulations. For these types of materials, Microrheology offers significant advantages:

  • Probes very high frequencies necessary for characterizing inherent short timescale, viscoelastic responses (whereas mechanical techniques are fundamentally limited by inertia).
  • Only requires microliter-scale volumes for rheological characterization of materials where sample volume is limited e.g. protein-based formulations.

Applications of DLS Microrheology include:

  • Rheological characterization of therapeutic proteins and biopolymer solutions.
  • Viscoelastic measurements of protein solutions to assess onset of protein-protein interactions and insoluble aggregate formation
  • Formulation development and screening.
  • High frequency rheology of dilute systems on process-relevant timescales.
  • Monitoring structure development in complex fluids with time or temperature, or structure breakdown on dilution.