Finite element analysis for a new design of NLC-cut quartz crystal resonant temperature sensor

In the process of designing resonant temperature sensors, getting minimal dimensions is required to decrease calorific capacity and response time. In this view, we investigated new shapes of sensing elements essentially obtained by modifying an initial resonator´s design. This design consists in plane parallel circular disk plates in NLC-cut for energy trapping by electrodes mass loading. Then, the disks are cut with two flats parallel to X crystallographic direction, thereby leading to designs intermediate between the common circular plates and so-called strip-resonator design. A combination of FEA simulations and of semi-analytical analyses were used to master the influence of width-to-thickness ratio onto the spectral characteristics of sensors, including the control of activity-dips occurrence. Q factors near 75000 and motional resistances near 9 Omega were obtained with sensors 4 mm-wide, operating on fundamental B-mode at 29.3 MHz, and exhibiting a temperature sensitivity close to 1000 Hz/K.