Hermetically Sealed Graphene Nanomechanical Resonators with Long-Term Stability and Ultrahigh Sensitivity

The excellent mechanical properties and gas impermeability make suspended graphene promising for the realization of nanomechanical resonators with high resonant frequency and high responsivity to pressure changes. However, the persistent gas leakage at the graphene/substrate interface hinders the application of graphene membranes in ultrasensitive pressure sensors with long-term stability. Here, we demonstrated that high-vacuum annealing can significantly improve the adhesion between graphene and the SiO₂/Si substrate, thereby achieving excellent temporal stability in fully sealed graphene drum nanoresonators. The average leakage rate of the annealed graphene devices was reduced by a factor of 1.2 × 10⁴, while the cavity pressure only dropped by 1.4% after 60 days of testing. The hermetically sealed graphene resonators show excellent long-term stability under both electrical and optical excitation, realizing a highly reproducible response to variations in gas pressure. Moreover, the proposed pressure sensor exhibits an ultrahigh pressure sensitivity of up to 310 kHz/mbar (corresponding to 2.99%/mbar) based on graphene resonators.