Nonlinear operation of resonant sensors based on weakly-coupled resonators: Experimental investigation of an actively-coupled architecture

[Display omitted] •Sensitivity to stiffness variation, to drive level and to noise of nonlinear WCRs is experimentally investigated.•Study is based on MEMS mutually injection-locked oscillator, with nonlinear restoring and damping forces.•Parametric sensitivity of amplitude ratio R and phase difference ϕ decrease above critical Duffing amplitude ADuff.•R is more robust to drive-level fluctuations and to intrinsic resonator noise than ϕ above ADuff and below the critical damping amplitude.•Theoretical analysis of properties of nonlinear WCRs is quantitaively validated. This paper is aimed at the validation of a theoretical analysis of the properties of nonlinearly-operated weakly-coupled resonators (WCRs) for resonant sensing applications. In particular, we investigate the relationships between the operating point of such devices and different performance indicators, such as parametric sensitivity, sensitivity to drive level and to noise, and bandwidth. To this end, a couple of high-Q MEMS resonators exhibiting nonlinear restoring and damping forces are used. A careful characterization of the resonators and their associated electronics is made, resulting in a very good, quantitative fit between the experimental results and those predicted by theory.