A Parametrically Tunable Airflow Sensor Based on Electrically Coupled Resonators

This article reports a mode-localized airflow sensor with tunable parametric sensitivity using electrically coupled double-ended tuning forks (DETFs). By adjusting the polarization voltage between the two resonant units, the coupling stiffness of the weakly coupled resonant system can be changed, thereby optimizing the output characteristics of the mode-localized airflow sensor. The adopted electrostatic coupling method is beneficial to optimizing the mechanical sensitivity of the device on the premise of satisfying the minimum coupling stiffness condition. Both theory and experiment results demonstrated that the reduction of the polarization voltage within a certain range is conducive to improve the mechanical sensitivity of the fabricated prototype. However, when the polarization voltage is reduced below 10 V, severe mode aliasing occurs, the mechanical sensitivity is no longer significantly improved, and the output linearity deteriorates drastically. Meanwhile, when the polarization voltage is set to 30 V, the tested prototype shows a mechanical sensitivity of
${2.044} \times {10}^{-{2}}$
/(m/s)2 and a detection threshold of 5.414 mm/s in terms of the output metric based on the subtraction of reciprocal amplitude ratios (SRARs).