Dynamics of a piezoelectric MEMS gas sensor based on coupled micromachined resonators

This work discusses the dynamics of MEMS structures; including a single cantilever, a single clamped-clamped beam, and a mechanically coupled cantilever and bridge resonator; actuated by Aluminum Nitride (AlN) layer, exploring the potential of coupled systems in gas sensing application. The pure AC actuation is applied on the piezoelectric layer and the corresponding frequency response of the three systems are discussed. The experimental results show different responses captured from different devices with the same structure, revealing the existence of induced axial stress in the AlN layer or contact surface, i.e., due to fabrication process as varying the applied AC voltages. To explore the system capabilities on gas sensing application, the weakly coupled system is heated via joules heating effect near a bifurcation point. The sensing performance for increasing Helium concentration is measured experimentally and shows high sensitivity and good linearity with low power consumption, which is suitable for IoT and wireless sensor networks applications.