A High Sensitivity Piezoelectric MEMS Accelerometer Based on Aerosol Deposition Method

MEMS accelerometers are widely employed in the Internet of Things (IoT) era. Among them, capacitive types are commonly used due to their low cost and compatibility with the commercial CMOS fabrication lines. However, piezoelectric MEMS accelerometers have great research popularity attributed to their wide working range, self-generating property and removal of the need for vacuum sealing. This study designs, fabricates and analyzes a piezoelectric cantilever-beam-based accelerometer in meso scale, which is constructed by a tungsten proof mass and a composite beam comprising of PZT and stainless steel layers. Four structures with different geometries/dimensions are designed for comparison, including rectangular and trapezoid beam shapes. All the devices are fabricated by MEMS processes where aerosol deposition is utilized to make high-quality PZT sensing layer. And the implementation of stainless steel substrate makes the fabrication flow simple and cost-effective. Experiments show that the natural frequencies of the four structures range from 572.25 Hz to 769.01 Hz, corresponding to respective working frequency range from 110 Hz to 150 Hz. The low frequency limit of 10 Hz is determined by a tailor-designed charge amplifier, which is used to amplify the output charge signal of the developed sensor. At the working frequency of 95 Hz, charge sensitivities of 23.9 pC/g to 41.4 pC/g are measured for the four structures. Comparison with other studies, the designed devices have high sensitivities.