Temperature dependent performance of piezoelectric MEMS resonators for viscosity and density determination of liquids

• Published in: Journal of micromechanics and microengineering Vol. 25; no. 10; pp. 105014 - 8
• Main Authors: Pfusterschmied, G, Kucera, M, Wistrela, E, Manzaneque, T, Ruiz-Díez, V, Sánchez-Rojas, J L, Bittner, A, Schmid, U
• Format: Journal Article
• Language: English
• Published: IOP Publishing 01.10.2015
• Subjects: Density; Deviation; elevated temperature; liquid sensing; Liquids; Mathematical models; MEMS resonators; Microelectromechanical systems; piezoelectric; Piezoelectricity; Resonators; Viscosity
• ISSN: 0960-1317; 1361-6439
• DOI: 10.1088/0960-1317/25/10/105014

It is the objective of this paper to report on the performance of piezoelectric MEMS resonators for viscosity and density measurements at elevated temperatures. A custom-built temperature controlled measurement setup is designed for fluid temperatures up to 100 °C. Piezoelectric single-side clamped resonators are fabricated, excited in 2nd order of the roof tile-shaped mode (13-mode) and exposed to several liquids (i.e. D5, N10, N35, PAO8, olive oil, ester oil and N100). At the next step, these results are analysed applying a straightforward evaluation model, thus demonstrating that with piezoelectric MEMS resonators the density (i.e. from kg m−3 to kg m−3) and viscosity (i.e. from mPa s to mPa s) values of liquids can be precisely determined in a wide range. Compared to standard measurement techniques, the results show for the first parameter a mean deviation of about 1.04% at 100 °C for all the liquids investigated. For the second parameter, the standard evaluation model implies a systematic deviation in viscosity with respect to the calibration being N35 in this study. This inherent lack of strength has a significant influence on the accuracy, especially at 100 °C due to fluids having a viscosity reduced by a factor of 30 for N100 compared to room temperature. This leads to relative deviations of about 23% at 100 °C and indicates the limits of the evaluation model.