LAUSR

In order to improve the sensitivity of micro-resonant gas sensors, the size of the resonator has to be reduced but this complicates the fabrication process. Therefore, a micro-resonant gas sensor with adjustable natural frequency is proposed in this article. The equivalent mass of the resonator is adjusted by a feedback signal, and its natural frequency is increased without reducing the resonator size. The mechanical-electro-chemical coupled dynamics equation of the sensor is established, its instantaneous frequency equation is obtained, and the instantaneous frequency variation during gas adsorption is analyzed. The results demonstrate an improvement in the sensor's sensitivity. The resonant sensor is fabricated, and the excitation and detection circuit is developed. The instantaneous frequency of the sensor is measured in ethanol vapor. The results show that the sensitivity of the sensor is increased by about 90 times when 180° feedback is added.