Simultaneous Enhancement of Sensitivity, Resonant Frequency, and Overload Capability of Piezoresistive Accelerometers by Heavily-Doped Fillet Structures on Sensing Beams

High sensitivity, high natural frequency, and high overload capability are desired for accelerometers used in industrial applications, but simultaneously enhancing all is challenging. Here, via designing novel heavily-doped fillet structures, we prove the sensitivity, resonant frequency, and overload capability can be simultaneously enhanced. The enhancements are attributed to regulations of stress concentration and effective sensing regions by the heavily-doped fillets. The sensors with and without fillets are designed, fabricated, packaged, and tested. The results show a sensitivity of 0.31 ± 0.02 mV/g at 5 V, a natural frequency of 37.87 ± 2.09 kHz, and an overload of 10040.17 ± 531.76 g for sensors with 10- $\mu $ m fillets, which are superior to 0.27 ± 0.01 mV/g at 5 V, 34.13 ± 0.90 kHz, and 7368.55 ± 843.92 g for those no-fillet counterparts. In addition, the developed sensor further exhibited feasibility in air-bearing vibration monitoring. The proposed design is envisioned to give insights into the novel designs of high-performance stress-based sensors, including accelerometers, pressure sensors, and strain gauges.