Mitigating spurious compressional waves in multi-measurand thickness shear mode sensors

There is a growing demand for multi-measurand monitoring of fluid properties in industrial settings. A notable example is in the area of fuels, lubricants, hydraulic fluids, and coolants, in which fluid aging and fluid contamination must be monitored and subjected to trend analysis to optimize preventive maintenance schedules. Typically these applications require viscosity measurement for immediate detection of catastrophic failure and employ conductivity and/or dielectric measurements for predictive measurements. The present work investigates unwanted compressional wave interactions in a multi-measurand thickness shear mode coupled resonator sensor, their mitigation, and the potential to employ the interactions to extract density and compressibility modulus information.