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

摘要

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 degrees 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 rho(min) = 785 kg m(-3) to rho(max) = 916 kg m(-3)) and viscosity (i.e. from mu(min) = 1.20 mPa s to mu(max) = 286.36 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 degrees 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 degrees 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 degrees C and indicates the limits of the evaluation model.