A mass sensor based on digitally coupled and balanced quartz resonators using mode localization

Abstract

This article goes through the implementation of a mass sensor based on mode localization with two coupled quartz resonators. The resonators are digitally coupled by the mean of a field programmable gate array that also allows to compensate their fabrication defects. As both this compensation and the coupling are digital, the two resonances can be close in frequency, especially as the Q factor of these resonators is much higher than that of conventional cantilevers, for example. This leads to an important mode localization, allowing to reach a resonance amplitude sensitivity of 14000, predicted by simulations and confirmed by experiments. Finally, it is shown experimentally that the two-resonator system is sensitive to a temperature change contrary to what is commonly assumed by the common-mode rejection property. This proves the necessity to systematically balance the resonators before each measurement.