Stiff-Filament Microrheology

Diffusing wave spectroscopy microrheology of actin filament networks.

Filamentous actin (F-actin), one of the constituents of the cytoskeleton, is believed to be the most important participant in the motion and mechanical integrity of eukaryotic cells. Traditionally, the viscoelastic moduli of F-actin networks have been measured by imposing a small mechanical strain and quantifying the resulting stress. The magnitude of the viscoelastic moduli, their concentratio...

Optical Microrheology of Biopolymers

We use passive and active techniques to study microrheology of a biopolymer solution. The passive technique is video tracking of tracer particles in the biopolymer, a technique which is well established. The active technique is based on rotating optical tweezers, which is used to study viscosity. A method to actively measure viscoelascity using time varying rotation of a particle trapped in opt...

Microrheology of complex fluids

The field of microrheology is concerned with how materials store and dissipate mechanical energy as a function of length scale. Recent developments in the theory and instrumentation of the microrheology of complex fluids are reviewed. Equal emphasis is given to the physical phenomena probed, advances in instrumentation, and specific experimental systems in which this field has already had an im...

Frequency modulated microrheology.

Coupling analog frequency modulation (FM) to the driving stimulus in active microrheology measurements conducted with optical tweezers effectively parallelizes numerous single-frequency experiments. Consequently, frequency modulated microrheology (FMMR) can efficiently characterize the dynamic stress response of complex fluids over several frequency decades in a single experiment. The time requ...

Large amplitude oscillatory microrheology