Viscosity sensor utilizing a piezoelectric thickness shear sandwichresonator

摘要

This paper describes a novel quartz crystal sensor for measurementnof the density-viscosity product of Newtonian liquids. The sensornelement consists of two piano-convex AT-cut quartz crystals vibrating inna thickness-shear mode with the liquid sample in between. This specialnset-up allows suppression of disturbing resonances in the liquid layer.nSuch resonances are generated in the common single-plate arrangementsndue to compressional waves caused by spurious out-of-plane displacementsnof the shear vibrating finite plate. The primary measurands of thensensor are the fundamental resonance frequency and the associatednresonance Q-value, which are influenced by the viscously entrainednliquid contacting the quartz surface. The sensor allows the measurementnof samples with viscosities from almost zero (air!) up to 200 cP with ansample volume of 130 Μl