Static and Dynamic Analyses of Electrostatically Actuated MEMS GO/CMUT Gas Sensor

This paper presents a detailed analytical investigation into the static and dynamic performance of a capacitive micromachined ultrasonic transducer (CMUT) functionalized with a graphene oxide (GO) sensing layer for gas detection applications. A bi-layer lumped-mass model is developed to capture the electromechanical response of the hybrid system, explicitly accounting for the mechanical stiffening effect of GO and its consequent influence on resonant characteristics. Static analysis reveals that the GO layer enhances operational stability by increasing the pull-in voltage from 143 V for a bare CMUT to 147.5 V. Dynamic assessments demonstrate that GO functionalization elevates resonance frequencies due to a stiffness-dominated regime, yielding a mass sensitivity of 24.19 Hz/pg at an 80 V DC bias. Frequency response analyses under combined DC/AC excitation highlight the system's linear dynamics, including distinct superharmonic resonances and bifurcation thresholds. The results underscore the role of GO in improving sensitivity, stability, and bandwidth, establishing GO/CMUTs as highly promising platforms for next-generation, high-performance gas sensors.