Low tension graphene drums for electromechanical pressure sensing

We present a process to fabricate electromechanical pressure sensors using multilayer graphene in a sealed drum geometry. The drum resonators are fabricated on insulating sapphire substrates with a local back gate for direct radio frequency (rf) actuation and detection of the mechanical modes. Using this scheme, we show the detection and electrostatic tuning of multiple resonant modes of the membrane up to 200 MHz. The geometry of the device also helps in attaining low tensile stress in the membrane, thereby giving high gate tunability (similar to 1 MHz/V) of the resonator modes. Westudy the resonant frequency shifts in the presence of helium gas and demonstrate a sensing capability of 1 Torr pressure in a cryogenic environment.