Performance enhancement of PEMC liquid level sensor subjected to environmental temperature variation

In this paper, the performance of a resonant Piezoelectric-excited Millimeter-sized Cantilever (PEMC) used as liquid level sensor has been studied. The sensitivity of this sensor affected by environmental temperature variation is investigated via theoretical and Finite Element Models (FEM). In order to validate this FEM, first, simulation results are compared with the theoretical and experimental ones for a sensor operating at constant room temperature. The simulation results are in a good agreement with experimental ones. Then, proposed theoretical model and FEM are used to study the dynamic behavior of the device when the environmental temperature is changed. The results indicate that although natural frequencies of sensor change due to temperature variation, the resultant shift remains almost the same regardless of specific immersion depths. Also, it can be concluded that temperature variation of about 50 A degrees C affects the liquid level measurement accuracy up to 29 mu m which is significant compared to a minimum detectable liquid level change of about 8 mu m by this sensor reported previously in literature.