Examinando por Autor "Steindl, Wolfgang"

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Piezoelectric MEMS resonators for density and viscosity sensing in engine oil with diesel fuel
(IEEE 2015 Transducers - 18th International Conference on Solid-State Sensors, Actuators and Microsystems., 2015-08) Toledo, Javier; Manzaneque, Tomás; Ruiz-Díez, Víctor; Kucera, Martin; Pfusterschmied, Georg; Wistrela, Elisabeth; Steindl, Wolfgang; Schmid, Ulrich; Sánchez-Rojas, José Luis
This work demonstrates the potential of AlN-based resonators as on-line sensors for monitoring lubricant oil dilution with diesel. Two devices are compared, one actuated in the first extensional in-plane mode and the other in an out-of-plane mode (14-mode). Both devices are designed to feature high quality factor in liquid, and allow discriminating variations in density or viscosity in the medium. Sensor resolutions for these two variables are compared in lubricant oil SAE 2.5W, and the device with the best result (14-mode) was also tested in continuous-flow measurements, showing a resolution of 0.5 ppm of diesel contamination in this oil.
Potential of Piezoelectric MEMS Resonators for Grape Must Fermentation Monitoring
(Micromachines - Multidisciplinary Digital Publishing Institute (MDPI), 2017-06-26) Pfusterschmied, Georg; Toledo, Javier; Kucera, Martin; Steindl, Wolfgang; Zemann, Stefan; Ruiz-Díez, Víctor; Schneider, Michael; Bittner, Achim; Sánchez-Rojas, José Luis; Schmid, Ulrich
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.