Potential of Piezoelectric MEMS Resonators for Grape Must Fermentation Monitoring

Abstract

In this study grape must fermentation is monitored using a self-actuating/self-sensing piezoelectric micro-electromechanical system (MEMS) resonator. The sensor element is excited in an advanced roof tile-shaped vibration mode, which ensures high Q-factors in liquids (i.e., Q ~100 in isopropanol), precise resonance frequency analysis, and a fast measurement procedure. Two sets of artificial model solutions are prepared, representing an ordinary and a stuck/sluggish wine fermentation process. The precision and reusability of the sensor are shown using repetitive measurements (10 times), resulting in standard deviations of the measured resonance frequencies of ~0.1%, Q-factor of ~11%, and an electrical conductance peak height of ~12%, respectively. With the applied evaluation procedure, moderate standard deviations of ~1.1% with respect to density values are achieved. Based on these results, the presented sensor concept is capable to distinguish between ordinary and stuck wine fermentation, where the evolution of the wine density associated with the decrease in sugar and the increase in ethanol concentrations during fermentation processes causes a steady increase in the resonance frequency for an ordinary fermentation. Finally, the first test measurements in real grape must are presented, showing a similar trend in the resonance frequency compared to the results of an artificial solutions, thus proving that the presented sensor concept is a reliable and reusable platform for grape must fermentation monitoring.

High performance piezoelectric AlN MEMS resonators for precise sensing in liquids

“…For this application, the sensor in the package is fully coated by a 4 µm thick amorphous silicon dioxide film to eliminate any parasitic leakage currents through the grape must, which would result in a lower R p value. The sensor is operated in the 15-mode and tested in model solutions N 1−9 and S 1−9 , which represent both normal and stuck fermentation stages [22]. The resonance frequency and quality factor are measured and used to calculate the density of the liquid according to [22,23].…”

“…The sensor is operated in the 15-mode and tested in model solutions N 1−9 and S 1−9 , which represent both normal and stuck fermentation stages [22]. The resonance frequency and quality factor are measured and used to calculate the density of the liquid according to [22,23]. Figure 8 shows both the ethanol concentration and the resonance frequency for normal as well as stuck fermentation.…”

“…A Lorentzian is fitted to the conductance spectrum shown in Fig. 13 to measure both f res and Q, which is then used to determine the dynamic viscosity of the investigated bitumen derivatives as described in [22,25].…”

Evaluation of Residual Stress of C Oriented AlN/Si (111) and Its Impact on Mushroom Shaped Piezoelectric Resonator 

“…Micro-electro-mechanical system (MEMS) based sensors and actuators are used in a wide variety of applications like military, aerospace, industrial, consumer electronics, healthcare, as well as in agriculture and environment monitoring [1][2][3][4][5][6][7][8][9][10]. The devices like pressure sensors, accelerometers, gyroscope, and temperature sensors are the few most sort after MEMS sensors for these applications [8,[11][12][13][14][15].…”

Editorial for the Special Issue on Piezoelectric MEMS

“… Piezoelectric MEMS resonators for measuring physical quantities such as mass, acceleration, yaw rate, as well as the pressure, viscosity, or density of liquids. Pfusterschmied et al [ 9 ] demonstrated that piezoelectric MEMS resonators with high quality factors in liquids can be used to monitor the change in grape must during wine fermentation, which is a direct quality indicator of the fermentation process. Yu et al [ 10 ] presented a unique take on the MEMS gyroscope through use of the acoustic Sagnac effect, which measured the phase difference between two sound waves traveling in opposite directions in a circular MEMS structure actuated by PMUTs.…”