Thermal-Actuation Piezoresistive-Detection Micromechanical Resonators with Quality Factor Self-Amplification Effect in Vacuum Environment

This paper reports on a micromechanical thermal-actuation piezoresistive-detection (thermal-piezoresistive) resonator (TPR), which offers advantages of quality factor self-amplification and has the advantage of low power consumption, working in the vacuum environment. The TPR consists of a dual-plane vibrating plate suspended by four beams while the two plates are connected by a nanoscale beam, with a negative piezoresistive effect. Self-excited oscillation is observed attributed to the thermal expansion and contraction caused by the Joule heating generated by the direct current (DC) bias current. We experimentally observed that when a DC bias current of 1.750 mA was applied to the nanoscale bundle, the TPR produced a quality factor of 9440. As the DC bias current was gradually increased from 1.750 mA to 2.925 mA, the effective quality factor improved from 9440 to 354030. The resistance of the nanobeam decreased from 2080 Ohm to 1839 Ohm. The investigation into the self-amplification of quality factor mechanism of the TPR lays a foundation for studying high quality factor and low-power resonators.