Characterization of Viscous and Viscoelastic Fluids Using Parallel Plate Shear-Wave Transducers

We introduce a recently devised approach for viscosity and viscoelasticity measurement using a device based on the excitation of acoustic shear waves in fluids, which opens up opportunities for rheological applications in the low kilohertz range. Two in-plane plate resonators, which are driven and read out electromagnetically, are aligned in parallel and are separated by a well-defined gap filled with the fluid sample. The lower plate is actuated, generating a shear wave in the viscous or viscoelastic fluid. The response on the second side is recorded in a frequency range, where intrinsic resonances of this setup are observed. The coupling of the two resonators increases with viscosity, yielding a, for resonator viscosity sensors unprecedented, high viscosity measurement range (measured up to 17.6 Pa . s). Analytical modeling and experimental results are presented.