Development of an electrostatic tuning method for resonant frequency control in a single-axis mems accelerometer

This study focuses on designing a single-axis MEMS (Micro-Electro-Mechanical Systems) accelerometer with an outer frame (M1) and an inner proof mass (M2). The main challenge is tuning the resonant frequency of the combined structure M1 and M2 to match that of the simpler M1 – only structure, while also enhancing the sensor's sensitivity, a key performance factor in practical applications. In this study, the frequency was successfully adjusted from 40.144 kHz to 38.229 kHz. Alongside this tuning capability, the sensitivity of the sensor showed a remarkable improvement: at an acceleration of 2G, the output signal increased from 0.29 picofarads (pF) to 1.45 pF, representing a fivefold enhancement. In the proposed design, both M1 and M2 are connected to specially designed electrostatic tuning electrodes. By applying controlled voltages to these electrodes, the stiffness of the system’s suspension springs labeled as K1 and K2 can be actively modified. This change in stiffness leads to an adjustment in the resonant frequency of the entire sensor structure. Through this electrostatic tuning method, it becomes possible to shift the sensor's operating frequency over a specific range. The effectiveness of this approach lies in the well-defined relationship between the spring stiffness values (K1 and K2) and the resonant frequency f1 of the system. By adjusting the spring constants, the resonant frequency can be tuned to match M1 – only structure's performance, with improved sensitivity. These findings offer valuable insights for advancing vibration and motion sensors. The combination of frequency tuning and enhanced sensitivity enables precision sensing in dynamic environments where performance and adaptability are crucial