The sensor for measuring the micro-displacements based on the piezoelectric resonator with lateral electric field

Theoretical and experimental studies of the influence of a thin metal film on the characteristics of a piezoelectric resonator with a lateral electric field showed the possibility of creating a micro-displacement meter in the range of 10-300 μm. For the experiments, two resonators based on the plates of PZT piezoceramics with a thickness of 3.56 and 4.46 mm with resonant frequencies of ~96 and ~260 kHz for both resonators were used. It has been experimentally established that in both cases, with an increase in the width of the gap between the free side of the piezoelectric resonator and thin aluminum film, the frequency of the parallel resonance and maximum value of the real part of the electrical impedance increase and reach saturation. Besides, it has been shown that the relative change of these values with a change in the width of the gap in the range 10-300 μm increases with decreasing the thickness of the resonator. In this case, the frequency of the series resonance practically does not change. It has been also established that the sensitivity of the resonator to the presence of a conducting film at the resonant frequency of ~96 kHz is significantly higher in comparison with the resonant frequency of ~260 kHz. The experimental results are in the qualitative agreement with the theoretical data.