Model of a Micromechanical Mode-Localized Accelerometer with an Initially Curved Microbeam as a Sensitive Element

The present study is devoted to mathematical modeling of the proposed new architecture of a microelectromechanical mode-localized acceleration sensor (MEMS accelerometer/gravimeter) with a sensitive element in the form of a clamped-clamped microbeam with an initial curvature, made in the form of the first asymmetric mode of free oscillations. The article demonstrates that with an asymmetric form of the initial curvature in the region of positive axial forces, there are zones of proximity of the frequency branches corresponding to the second symmetric and the first asymmetric vibration modes. When the required value of the axial tensile force in the microbeam is provided structurally, this effect can be used, in particular, to measure the axial component of the transfer acceleration according to the principle of amplitude modal localization. The possibility of heating the sensitive element with the help of an electric current flowing through the microbeam, provided in the sensor layout, makes it possible to control the operating point of the oscillation mode and, thus, to vary the range of measured accelerations and the degree of sensor sensitivity within a very wide range. The configuration of the oscillation excitation and output signal pickup electrodes proposed in the article makes it possible, with the help of a feedback loop, to stabilize the oscillation amplitude at the required level in the working (third) symmetrical form and, at the same time, to measure the oscillation amplitude associated with the change in the value of the measured component of the portable acceleration according to the asymmetric form. Thus, a mathematical model of an original mode-localized accelerometer (gravimeter) containing a single sensitive microbeam element and involving the effect of energy exchange between its various modes of vibration is proposed and investigated in the article.