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.

电容驱动与压阻检测（CAPD）机制已被用于提升谐振式加速度计的带宽，其利用高转换增益来放大微弱信号。尽管具备这些优势，压阻应变片所用梁的刚度仍为实现高灵敏度与分辨率带来了挑战。为解决这一局限，本文提出一种采用热增强方法提高灵敏度、具有更高比例因子的高分辨率谐振式加速度计。该加速度计的核心是CAPD谐振器，其由一双端固支梁（clamped-clamped beam）构成，梁上对称布置了两个压阻应变片。通过在这两个分别记为G1和G2的压阻应变片两端施加直流热电压，由于两片之间的电阻差异会产生热扰动刚度。这种刚度会改变谐振器同相模式与异相模式之间的耦合，从而提升谐振式加速度计的比例因子。实验结果表明，该方法可将噪声谱密度从2.4 µg/√Hz显著降至0.9 µg/√Hz，同时保持约1000 Hz的高带宽。这一进展凸显了热扰动在提升比例因子方面的有效性，实现了1111的带宽-噪声基底比，为目前已报道的最高值。