The ultra-high sensitivity of mass resonator achieved by the beam with variable thickness

Abstract

The shift of resonant frequency due to the particle adsorption is the mass sensing mechanism of a micro/nano-resonator. The sensitivity and resolution are the two key performance indicators of a mass resonator. An effective method to significantly enhance the sensitivity of a mass resonator is presented. The method is realized by the design of the beam resonator thickness variation along the longitudinal direction. The analytical expression of the non-uniform resonator sensitivity and the optimization process on the thickness are given. The optimal shapes of the cantilevered and doubly clamped beam resonators are obtained by the optimization process. The sensitivities of the beam resonators in the optimal shapes are three orders of magnitude higher than those of the uniform ones. A systematic method of enhancing the sensitivity of a mass resonator through the shape optimization is thus provided. The influences of the axial load on the optimization results are also discussed.