A Differential Pressure Wave-Based Sensor Setup for the Acoustic Viscosity of Liquids

We investigate a differential sensor setup utilizing acoustic pressure waves, which aims at the determination of the acoustic viscosity (or the second coefficient of viscosity) of highly viscous liquids with shear viscosities in the range of several 100 mPa · s and above. The whole setup is modeled in PSPICE and investigated experimentally. The presented approach is suitable for further miniaturization and is based on a differential configuration, such that spurious effects associated with the parameter spread of the used lead-zirconate-titanate transducers ideally cancel out. We demonstrate the operation in time domain (avoiding spurious interference effects), present an according calibration procedure with a known reference liquid, and discuss the effects of diffraction. Finally, the experimental results demonstrate the applicability of the setup.