Synchronization And Its Applications In Nonlinear Micromechanical Oscillators

Micromechanical oscillators have been widely used in mobile electronic devices and sup-posed to play an imperative role in Internet of Things(IoT)and smart city,due to their excellent compatibility to IC(Integrated Circuit),tiny dimensions and many other advantages.The nonlin-earity emerges in micromechanical oscillators under scale effect along with the tendency toward to smaller dimensions and higher precision.Some nonlinear effects can be properly utilized to circumvent the detrimental effects originating from the nonlinearity itself,even surpass the fun-damental limits in linear regime.As one of the aforementioned nonlinear phenomena,synchro-nization is a ubiquitous phenomenon in nature.This thesis aims to study the primary properties of synchronization,reveal the effects on nonlinear scillators and finally harness the positive features for improving the dynamic performances of oscillators and sensors.Starting from the three ma-jor contents consisting of the synchronization to external force,mutual synchronization between coupled oscillators and the applications of synchronization,we focus on addressing four prob-lem including tuning the synchronization region,improving the frequency stability,uncovering amplitude-frequency dependence during synchronization and the remote synchronization ampli-fication.The researches are listed below:1.The dynamic model of a nonlinear micromechanical oscillator synchronized to an external perturbation is established.The influences of external perturbation on synchronization region and frequency stability are revealed.The approximate analytical expressions of synchronization region and Allan deviation are given theoretically and verified by experiments,which can effectively predict the trend of synchronization region and frequency stability.2.The adjustment mechanism of phase delay in closed-loop feedback to the synchronization region is proposed for the first time.Theoretically and experimentally,the relationship between the position and size of the synchronization region as a function of phase delay is given.The region is bridged with the hysteresis interval of the nonlinear amplitude-frequency response and can be expanded for more than 10 times by tuning the phase delay.3.The relationship of amplitude and frequency of a micromechanical oscillator in syn-chronization is revealed.Counter-intuitively,it is found that the linear oscillator has a nonlinear amplitude-frequency dependence while the nonlinear oscillator has a linear dependency.This phenomenon is explained with theoretical analysis and experiments.4.High-order mutual synchronization in micromechanical oscillators has been studied.The frequency regulation method of frequency difference adjustment using piezoresistive sensing method is proposed,and the influencing factors of synchronization region and oscillation frequency sta-bility in mutual synchronization are explored.The relationship between the amplitude-frequency dependence of coupled oscillators and the frequency-sensitive characteristics in the coupled syn-chronization system are revealed.5.The remote synchronization amplification sensing mechanism is proposed for the first time based on the frequency locking phenomenon.The prototype is designed for experimental verification.The results show that this technique can enhance the sensitivity of the charge sensor(electrometer)by 9 times and simultaneously improve the frequency stability by 3 times.This thesis provides novel ideas for designing micromechanical oscillators and sensors.