A novel differential configuration of a high-resolution mode-localized resonant SOI-MEMS accelerometer is presented in this paper. An effective maximum scale factor of 11/g and a bias-stability of 2.96μ g is demonstrated. A minimum noise floor of 3μ g/√Hz is shown for device operation in an optimum working region. A large bandwidth of 350Hz is reported and methods to electronically tune the working bandwidth are described. These results benchmark mode-localized accelerometers favourably with respect to other high-end low-g commercial MEMS accelerometers.

This paper presents results from the closed-loop characterization of an electrically coupled mode-localized sensor topology including measurements of amplitude ratios over long duration, stability, noise floor and the bandwidth of operation. The sensitivity of the prototype sensor is estimated to be -5250 in the linear operation regime. An input-referred stability of 84ppb with respect to normalized stiffness perturbations is achieved at 500s. When compared to frequency shift sensing within the same device, amplitude ratio sensing provides higher resolution for long term measurements due to the intrinsic common mode rejection properties of a mode-localized system. A theoretical framework is established to quantify noise floor associated with measurements validated through numerical simulations and experimental data. In addition, the operating bandwidth of the sensor is found to be 3.5Hz for 3dB flatness.

In this letter, we experimentally demonstrate the existence of an optimal operating region in a resonant microelectromechanical systems sensor utilizing the principle of vibration mode localization, to achieve ultra-high resolution amplitude ratio measurements. We have shown analytically that the coupling strength and stiffness mismatch between the two resonators are primary parameters that influence the resolution of the amplitude ratio measurements within such a sensor. Using this optimization strategy, a minimum noise spectral density equivalent to 16 ppb/Hz^1∕2 in terms of normalized stiffness perturbation is experimentally demonstrated. This is by far the best resolution achieved in this type of sensor. These results can be used to aid the design of future high resolution sensor employing mode localization.