Mode localized artificial hair sensor with enhanced linearity applied for dual-axis air flow sensing

Abstract

Abstract The weakly coupled resonators based on mode localization are promising in emerging signal measurement fields due to the verified relative mechanical sensitivity enhancement and exceptional ambient robustness. In this work, we report a novel mode localized artificial hair sensor for dual-axis air flow sensing. A new full-scale linear output metric based on differential subtraction of reciprocal amplitude ratios (SRAR) is proposed to suppress the strong inherent non-linearity of amplitude ratio-modulated output metric. The theoretical derivation of mechanical sensitivity demonstrates that the differential SRAR output is strictly linear with the square of input air flow velocity. The fabrication process based on standard deep dry silicon on glass is described and an optimized control and measurement system composed of an analog interface circuit and a digital signal processing circuit is designed for experimental performance evaluation. The tested prototype shows an x-axis mechanical sensitivity of 5.417 × 10−2/(m s)−2 with an x-axis cross-axis coupling coefficient of 0.067 and a y-axis sensitivity of 6.212 × 10−2/(m s)−2 with a y-axis cross-axis coupling coefficient of 0.055. The comparative experiment results confirm that compared to frequency-based output and amplitude ratio-based output, the differential SRAR-based output not only promotes the relative mechanical sensitivity and linearity but also exhibits the superior bias stability, which indicates a better common-mode rejection of ambient fluctuations.