On the Dynamic Range and Resolution of Thermal-Piezoresistive Resonant Mass Sensors

Thermal-actuation and piezoresistive-detection effects have been employed to pump the effective quality factor of MEMS resonators, targeting better mass sensing performance in air. In this paper, frequency resolution (bias instability) of a thermal-piezoresistive resonator operating in air at room temperature is experimentally investigated. It is found that the dynamic range decreases when increasing the bias direct current whereas the effective quality factor rises. The measurement results indicate a maximum effective quality factor of 169k with a dynamic range of 47.8 dB for a bias current of 6.25 mA, and a minimum effective quality factor of 11.3k with a dynamic range of 70.1 dB for a bias current is 5.8 mA. Our work also shows that the frequency and amplitude bias instabilities are significantly lower due to the dynamic range decrease for a high bias current.