Chemical sensing based on graphene-aluminum nitride nano plate resonators

This paper reports on an innovative chemical sensing mechanism based on the effective transduction of the analyte induced variations in the electrical conductivity of a graphene electrode employed to excite mechanical vibration in an Aluminum Nitride (AlN) piezoelectric nano plate resonator (NPR). We show that the use of a single atomic layer graphene as a virtually massless and strainless electrode for AlN NPRs not only boosts the operating frequency (up to 63% higher f0) and electromechanical performance (up to 2× improved Q) of the devices, but it also enables unique chemical sensing capabilities. We experimentally demonstrate that the variations in the graphene electrode conductivity upon chemical doping can be efficiently detected by monitoring the corresponding induced variations in the vibration amplitude of the graphene-AlN (G-AlN) NPR, without the need of direct electrical probing of the graphene sensing layer. The effectiveness of the proposed sensing mechanism is experimentally verified by monitoring a progressive fluorination of the graphene electrode, which gradually converts it to an insulator. A 2 dB change in resonance amplitude is recorded when the G-AlN NPR is exposed to a highly diluted concentration of XeF2 vapor (XeF2 partial pressure ~1/36 in N2) for 2 minutes.