Measurement error estimation and quality factor improvement of an electrodynamic-acoustic resonator sensor for viscosity measurement

• We introduce electrodynamic-acoustic viscosity sensor.
• We discuss working principle of sensor and measurement setup.
• We discuss repeatability measurements and error estimation methods.
• We discuss the effect of increasing magnet separation on sensor performance.
• We discuss methods of improving the initial Q factor of the sensor in air.

Miniaturized resonating viscosity sensors operating at frequencies in the low KHz-range, offer portability and measurement results comparable to existing lab viscometers. In this paper, we present a viscosity measurement cell, based on a concept that we proposed earlier utilizing electrodynamic-acoustic resonator sensors, with a novel design based on interchangeable resonator cards. Experimental results obtained with the new resonator cards show the dependence of the resonance frequency and Q-factor on viscosity. We obtained repeatability errors in the order of a few percent for a range of Newtonian liquids. We discuss the related errors in viscosity measurement based on deviations in the determination of the Q-factor and resonance frequency. In addition, experiments were made aiming at increasing the initial Q-factor of the sensor by varying the distance separating the two magnets of the viscosity measurement cell and investigating different bonding techniques of the resonator card. Based on these results, design rules for the magnetic circuit and the mounting are derived.