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M. Gröschl, R. Thalhammer, G. Karlowatz, E. Benes, H. Nowotny:
"Viscosity monitoring with a quartz crystal thickness shear resonator";
in: "Proc. 1st Congress of Alps Adria Acoustics Association / 3rd Congress of Slovenian Acoustical Society", M. Cudina (Hrg.); Slovenian Acoustical Society, Portoroz/Slowenien, 2003, ISBN: 961-6238-73-6, S. 663 - 672.

The paper describes a novel quartz crystal sensor for the measurement of the densityviscosity
product of Newtonian liquids. The sensor element consists of two circular quartz
crystal plates with an air-gap in between and the liquid sample in contact with the outer
plate surfaces. Plano-convex AT-cut quartz crystals arranged in mirror symmetric crystallographic
orientation and vibrating in an even-symmetric thickness-shear fundamental
mode at 2.77 MHz are utilized. The two outer plane sides of the crystals are fully covered
by gold electrodes, which are both connected to ground potential. This special mirror
symmetric set-up allows the compensation of spurious displacements in the circular
clamping zones of the two crystals. The measurement values of the sensor are the fundamental
resonance frequency f and the associated resonance Q-value, which are analytically
dependent on the density-viscosity product of the liquid in contact with the sensing surfaces.
The sensor covers a viscosity range from almost zero (air!) up to 2000 Pa.s, and is
not restricted to electrically insulating liquids.
Keywords: Resonant sensors, BAW sensors, viscosity, dough

http://aleph.ub.tuwien.ac.at/F?base=tuw01&func=find-c&ccl_term=AC04405879