2D material attached quartz crystal microbalance for sensing SF6 gas flow under humid condition

The authors report quartz crystal microbalance (QCM) integrated with hexagonal boron nitride-graphene (hg) monolayer heterostructure as a sensor to detect mass flow of sulphur hexafluoride (SF6), an important electrical insulating gas, under humid conditions. Their recent work demonstrated an enhancement in QCM sensing characteristics upon attaching monolayer 2D materials onto the QCM electrode surface and its application for improved relative humidity measurement. Here, they extend this approach to detect flow of SF6 gas causing variation in relative humidity. They fabricated a hg-QCM sensor by transferring the heterostructure thin film onto the QCM electrode surface using a standard wet transfer technique and measured return loss of the QCM under SF6 gas flow at a selected RH condition. The mass flow of the humid SF6 gas effects perturbation in damping at the QCM surface as indicated by changes in the motional resistance of the QCM. The motional resistance changes introduced significant variation in loaded Q-factor, the magnitude of which was gas species-dependent, thus allowing to distinguish SF6 from other common electronics gases.