Research progress of electromechanical graphene resonant sensors

The resonant sensor is a kind of high-sensitivity and high-stability sensor that directly outputs digitalsignals. The resonance sensitive elements of traditional resonant sensors are mostly made of metal, quartzcrystal, silicon and other materials. However, with the development of resonant sensor toward theminiaturization and intellectualization, the sensitive materials of new resonator are micro-nano machined andhighly sensitive. As a new type of two-dimensional nanomaterial, graphene has the great potentials in the fieldof resonance sensing because of its excellent mechanical, electrical, optical and thermal properties. Therefore,the mechanical quantity sensor based on graphene material is expected to surpass the silicon materialmechanical quantity sensor in many aspects such as micro-nano size, high performance, and environmentaladaptability. This review focuses on the graphene resonant mechanical quantity sensor. In the first part, wesummarize the basic properties, preparation methods, and transfer methods of graphene materials. Thepreparation and transmission methods of graphene are key to high-performance graphene resonator, but thereare still different problems in the preparation and transfer of graphene, which also greatly restricts thedevelopment of graphene resonator. In the second part, the basic theory of resonant sensors is given, and thecommon methods of transferring graphene films are introduced in detail. Then the theoretical and experimental studies of graphene resonator are discussed. For example, the theoretical studies of graphene resonator areinvestigated by using the classical elastic theory, non-local elastic theory, molecular structure mechanics andmolecular dynamics. Then the effects of graphene preparation method, graphene layer number and shape,excitation and detection methods on the resonance performance are estimated in the resonant experiments ofgraphene resonators. After that, the research progress of graphene resonator is summarized in the fields ofpressure, acceleration and mass sensors. Compared with traditional silicon resonators, graphene resonators havea small dimension and demonstrate preferable resonant performance under low-temperature and low-pressureconditions. In this case, the technical issues of graphene resonant sensor are introduced to emphasize theimportance of suspended graphene film transfer, structure fabrication of harmonic oscillator and vibrationexcitation/detection of resonators, which contributes to the potential applications in the fields of aerospace,intelligent detection and biomedical sensing for graphene resonant sensors