Sensitivity enhancement using a nonlinear resonator

Changes to the resonant frequency of a micromechanical resonator can potentially be used as a basis for chemical or biological detection. Any resonant frequency changes can be detected by the resulting change in amplitude or phase of the resonators response at a particular frequency. A Duffing resonator has sudden transitions in both amplitude and phase at two critical frequencies which could be exploited to enhance the sensitivity of resonator based sensors. In this paper a system to determine the phase response of a Duffing resonator is described. This system is then used to show that a Duffing resonator is significantly more sensitive to changes in resonant frequency than that the equivalent linear resonator.