Design, Simulation, and Modeling of a Highly Sensitive Multicapacitor Piezoelectric MEMS Accelerometer

Increasing the on-chip sensitivity of an accelerometer enhances the transduction efficiency at the sensor level, thereby improving the signal-to-noise ratio (SNR) without introducing additional electronic noise. To enhance the sensitivity of the piezoelectric accelerometer, we report a novel series-connected multicapacitor pickup MEMS design. Using well-calibrated COMSOL simulations, we show that the number of series-connected integrated capacitors in the construction directly correlates with the differential sensitivity of the multicapacitor piezoelectric accelerometer. In this technique, the voltage across all the series capacitors in the structure is equal to that across the single-capacitor structure. A multicapacitor pickup structure can be designed using two, four, six, or more capacitors. The design is demonstrated using aluminum nitride (AlN) as a piezoelectric material, but it can be extended to other materials such as lead zirconate titanate (PZT) and zinc oxide (ZnO). Furthermore, we have developed a mathematical model for the multicapacitor structure of the piezoelectric accelerometer, and the results are compared with the simulated data, showing excellent accuracy with an error of less than 4%. The proposed method demonstrates significant potential for improving the efficiency of various vibration-sensing/energy-harvesting MEMS structures. The device proposed in this work has a wide range of applications, including autonomous systems, machine/structure health monitoring, and navigation systems.