Low resonant frequency MEMS mechanism based on nonlinear stiffness beam

In order to meet the requirement of high precision measurement, the resonant frequency of MEMS accelerometer becomes more and more lower. This paper presents a structural design to achieve an extremely low resonant frequency in an MEMS spring mechanism, which is based on nonlinear stiffness beam. The mechanism employs a curved beam to achieve a negative stiffness. By adding this negative stiffness behavior to the positive stiffness of a normal folded beam, a quasi-zero stiffness mechanism can be obtained. Analytic calculation and the finite element analysis (FEA) are used to describe its nonlinear mechanical behavior. The mechanism is fabricated preliminarily and tested to verify a low resonant frequency can be successfully actualized.