Research progress of electromechanical graphene resonant sensors

Abstract

The resonant sensor is a kind of high-sensitivity and high-stability sensor that directly outputs digital signals. The resonance sensitive elements of traditional resonant sensors are mostly made of metal, quartz crystal, silicon and other materials. However, with the development of resonant sensor toward the miniaturization and intellectualization, the sensitive materials of new resonator are micro-nano machined and highly sensitive. As a new type of two-dimensional nanomaterial, graphene has the great potentials in the field of 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 material mechanical quantity sensor in many aspects such as micro-nano size, high performance, and environmental adaptability. This review focuses on the graphene resonant mechanical quantity sensor. In the first part, we summarize the basic properties, preparation methods, and transfer methods of graphene materials. The preparation and transmission methods of graphene are key to high-performance graphene resonator, but there are still different problems in the preparation and transfer of graphene, which also greatly restricts the development of graphene resonator. In the second part, the basic theory of resonant sensors is given, and the common 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 are investigated by using the classical elastic theory, non-local elastic theory, molecular structure mechanics and molecular 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 of graphene resonators. After that, the research progress of graphene resonator is summarized in the fields of pressure, acceleration and mass sensors. Compared with traditional silicon resonators, graphene resonators have a small dimension and demonstrate preferable resonant performance under low-temperature and low-pressure conditions. In this case, the technical issues of graphene resonant sensor are introduced to emphasize the importance of suspended graphene film transfer, structure fabrication of harmonic oscillator and vibration excitation/detection of resonators, which contributes to the potential applications in the fields of aerospace, intelligent detection and biomedical sensing for graphene resonant sensors.