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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. [ABSTRACT FROM AUTHOR]

A new humidity sensor based on graphene oxide quantum dots (GOQDs)/polyelectrolyte [polymer (diallylimethyammonium chloride) (PDDA)] composite sensing films was proposed. A few layers of GOQDs anchor on PDDA were prepared on the substrate via covalent bonds. A 0D scale, hydrophilicity, and super‐permeation of GOQDs endow the sensor an ultrafast response with about 32 ms response time and 48 ms recovery time. Meanwhile, the response was hardly affected due to covalent anchor of the composite film even after the sensor was soaked in water for several times. [ABSTRACT FROM AUTHOR]

A new method to analyse the contact resistance of a carbon nanotubes (CNTs) humidity sensor is proposed. By analysing the Cole‐Cole plots of the sensor impedance, which was tested by an electrochemical workstation in different RH environments, the contact resistance could be achieved. According to this novel analytical method and the experimental data, the contact resistance of the sensor was about 5 Ω, which was much smaller than the resistance of the sensing film. [ABSTRACT FROM AUTHOR]