Three-axis Piezoresistive MEMS Accelerometer with Extended Twin Mass Structure

In this paper, we report the design and Finite Element Analysis (FEA) based simulation of a novel three-axis MEMS piezoresistive accelerometer with high resonant frequency and sensitivity. The design of this accelerometer allows extended bandwidth without compromising the sensitivities in all the three axes. The accelerometer also exhibits good cross-axis performance. The resonant frequency can be increased further without affecting the sensitivity of our proposed device by reducing the length of the intermediate beam. We have suggested a new approach to reduce the length of the intermediate beam by extending the proof mass into the intermediate beam. The resulting device showed an increase in the mode 1 frequency by 2 kHz along with a considerable increase in the z-axis acceleration sensitivity by 10 microvolts for 1 g of acceleration. Whereas, the device with direct reduction of length of the intermediate beams exhibited an increase in the mode 1 frequency by 2 kHz without any improvement in the sensitivity.