a The proposed synchronized resonant accelerometer consists of a microelectromechanical resonant accelerometer, a reading resonator, and a frequency-tracking system. The concept behind the design is to decouple the sensing mode and the reading mode through two isolated resonators as well as to improve the resolution of the accelerometer. b Spectrum response of the sensing resonator (orange) and the reading resonator (cyan) during a typical synchronization process. Through the unidirectional electrical coupling method, a sidelobe can be observed in the spectrum of the reading resonator (stage I), which shifts as the induced external acceleration changes (stage II). When the sidelobe is close enough to the resonant peak of the reading resonator, the latter is synchronized to the former, and a jumping of the main peak can be observed (stage III).