Dynamics and structure of complex fluids from high frequency mechanical and optical rheometry

High frequency rheometry here defined as measurement of dynamic shear moduli in the frequency range beyond that accessible by conventional rotational rheometry (f > 102 Hz) provides insight into microstructure and local dynamics of complex fluids. We review the mechanical devices as well as the optical and other microrheological techniques available today, discussing especially the frequency and modulus range the different methods cover. We also emphasise on the comparison between optical and mechanical methods and finally, on the microscopic structural and dynamic information extracted from high frequency rheology on complex fluids like polymers, surfactants, biomaterials and colloidal dispersions.