Review of Quality-factor Controls of Micro/Nano Mechanical Resonators using Structural Methods

Quality factor (Q factor) is one of the important parameters for mechanical resonant sensors. The higher Q factor contributes to higher sensitivity for physical sensors, while lower responsiveness, and vice versa, which means the appropriate values of Q factor depend on its application. Therefore, Q factor controlling is a primitive technique for physical sensors using mechanical resonators. In the past, many researches for Q factor controlling have been conducted. Electrical feedback methods and external pumping methods are representative. These well-established methods need to add external equipment to the resonators systems. In this paper, novel Q factor control methods are introduced; one is non-linear vibration damping, another is a variable phononic bandgap. Non-linear vibration damping occurs in especially nano-mechanical resonator and can control the Q factor by just changing the vibration amplitude of the resonator. Also, the phononic bandgap generally does not propagate actuation vibrations. The introducing phononic device can change the bandgap as to include and exclude the resonant frequency of the resonator, which works to control the Q factor. These introduced methods achieve simple systems and good compatibility with conventional MEMS, which are expected as interesting Q factor control methods.