High-sensitivity ScAlN piezoelectric MEMS accelerometer via bimorph structure design

This study presents a cantilever piezoelectric microelectromechanical systems (MEMS) accelerometer based on a bimorph structure with a compact size and high sensitivity. First, an analytical model is established for the voltage sensitivity of a bimorph, incorporating the effects of electrode layers. Theoretical analysis and experimental results confirm that the bimorph structure provides additional capacitance-derived design freedom while maintaining the same natural frequency and voltage sensitivity as a unimorph. Additionally, a design strategy is proposed to maximize voltage sensitivity. By optimizing the cantilever dimensions and implementing a series array within the minimum natural frequency and capacitance constraints, a device with a natural frequency of 1.1 kHz and a sensitivity of 12.94 mV g −1 at 300 Hz is achieved. The area-normalized sensitivity ( 10.69 mV g − 1 mm − 2 ) significantly surpasses comparable results reported in the literature based on unimorph structures. This study demonstrates the significant potential of bimorph structures in piezoelectric MEMS accelerometer design, offering a high-performance solution for space-limited and low-frequency vibration monitoring applications.