Direct and controlled device integration of graphene oxide on Quartz Crystal Microbalance via electrospray deposition for stable humidity sensing

Electrospray deposition coats a 10 MHz QCM with graphene oxide with nanogram control, spreading it evenly over the electrode instead of in clumps as drop-casting or dip coating do. The sensor then oscillates stably from 11 to 97% relative humidity; more graphene oxide raises sensitivity, while less gives lower noise and detection limit. The method also works with other nanomaterials.