Enhancing the linear dynamic range of a mode-localized MEMS mass sensor with repulsive electrostatic actuation

This letter demonstrates the linear dynamic range enhancement of a mode-localized microelectromechanical systems sensor based on two weakly coupled cantilevers under electrostatic actuation resulting in a repulsive force. An analytical model is proposed to design the sensor, and the expression of the electrostatic force is obtained using a finite element simulation. Compared to attractive electrostatic actuation, the intensity of the resulting force is less sensitive to the change in the cantilever's displacement, with negligible electrostatic nonlinearities. This result is confirmed by experimental measurements showing linear vibrations up to 70% of the gap, which is almost three times higher than the electrostatic critical amplitude of a similar device using attractive electrostatic force. Finally, the mass sensing capability is highlighted by depositing a few picograms of platinum on the sensor.