High-Frequency Microrheology using a Cantilever Pair in Fluid

Measuring the rheological properties of small quantities of complex fluids at high frequencies remains an important challenge with many current technological applications. The field of two-point microrheology has made great strides yet most available approaches are subject to significant experimental and theoretical constraints regarding the accessible frequencies of measurement. In this talk, we explore the high-frequency motion of a pair of micron scale cantilevers in fluid to probe its rheological properties for a broad range of conditions. Using currently available cantilevers, it is possible to access MHz frequencies in a viscous fluid. We explore the motion of cantilever pairs that are either driven externally or by Brownian motion. We use the motion of an individual cantilever and the fluid-coupled motion of a cantilever pair to quantify the properties of the surrounding fluid. We focus here on analytical and numerical results for a range of Newtonian and power-law fluids and compare our findings directly with experimental measurements where possible.