A High-Resolution and Large-Bandwidth Resonant Accelerometer with Thermal Boost Sensitivity

Capacitive actuation and piezoresistive detection (CAPD) mechanisms have been explored to enhance the bandwidth of resonant accelerometers, leveraging their high transduction gain to amplify weak signals. Despite these advantages, the stiffness of beams for the piezoresistive gauges poses a challenge to achieving high sensitivity and resolution. To address this limitation, this paper presents a high-resolution resonant accelerometer with enhanced scale factor using a thermal boost approach to increase sensitivity. The accelerometer features a CAPD resonator consisting of a dual clamped-clamped beam with two symmetrically arranged piezoresistive gauges. By applying a DC thermal voltage across these piezoresistive gauges, denoted as G1 and G2, a thermal perturbation stiffness arises due to the resistance difference between the two gauges. This stiffness alters the coupling between the in-phase and out-of-phase modes of the resonator, enabling enhancements to the scale factor of the resonant accelerometer. Experimental results show that this approach significantly decreases the noise spectral density from 2.4 µg/√Hz to 0.9 µg/√Hz, while maintaining a high bandwidth of ~1000 Hz. This advancement highlights the effectiveness of thermal perturbation in boosting the scale factor, achieving a bandwidth-to-noise floor ratio of 1111, the highest reported to date.