A Novel Model of a Mode-Localized MEMS Accelerometer
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A Novel Model of a Mode-Localized MEMS Accelerometer Academician N. F. Morozova,b,*, Corresponding Member of the RAS D. A. Indeitsevb,c,
V. S. Igumnovac, Ya. V. Belyaevd, A. V. Lukinc, I. A. Popovc,**, and L. V. Shtukinb,c Received July 13, 2020; revised July 13, 2020; accepted July 14, 2020
Abstract—In this work, a model of a microelectromechanical accelerometer with two movable beam elements located between two stationary electrodes is proposed. The action of inertia forces in the longitudinal direction leads to a change in the spectral properties of the system, which can be used as an output signal of the sensor. The dynamics of the system in the presence of weak electrostatic coupling between the sensitive elements is characterized by the phenomenon of modal localization, which is a significant change in the amplitude relationships for the forms of in-phase and antiphase oscillations with small changes in the measured component of the object’s acceleration vector. It has been shown that the sensitivity of the proposed sensor based on modal localization can be orders of magnitude higher than the sensitivity of systems based on measuring the shift of natural frequencies. Keywords: MEMS, accelerometer, weakly coupled systems, modal localization DOI: 10.1134/S1028335820100031
INTRODUCTION The classical scheme of a micromechanical accelerometer is an inertial mass, characterized by one degree of freedom, on an elastic suspension [1]. In the presence of portable acceleration, the inertial mass is quasi-statically displaced, which leads to a change in the capacitance of the comb or plane-parallel electrode structure and the appearance of a useful signal in the electric circuit. Schemes of the operation of micromechanical accelerometers in the open loop mode [2] and in the compensation mode [3, 4] are well known. The modern direction of development in the field of micromechanical accelerometers is the creation of resonant sensors [5]. Unlike quasi-static circuits, in a resonant accelerometer the sensitive element performs harmonic oscillations at one of its natural frequencies. The transferred inertial forces lead to a change in the spectral properties of the elastic system (displacement of resonant frequencies), which is the output signal of the sensor. The use of differential circuits with a frequency output allows achieving high temperature stability and vibration stability of the system [6, 7]. a St.
Petersburg University, St. Petersburg, Russia for Problems in Mechanical Engineering, Russian Academy of Sciences, St. Petersburg, Russia c Peter the Great St. Petersburg Polytechnic University, St. Petersburg, Russia d Concern CSRI Elektropribor, St. Petersburg, Russia *e-mail: [email protected] **e-mail: [email protected] b Institute
In recent years, a new generation of micromechanical resonators has been intensively developed. The new class of devices is based on the use of the phenomenon of modal localization in loosely coupled systems [8–10]. The ability of systems with many degrees of freedom to locali
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