Progress and perspectives of high-quality mechanical properties testing and mechanisms for 2D materials

Two-dimensional (2D) materials have attracted extensive attention from aerospace, integrated circuits, precision sensors, and flexible electronics due to their unique layered structure and excellent physicochemical properties. In practice applications, the components of functional nanodevices are subjected to mechanical stress, which can affect the robust performance and structural reliability of these devices. Therefore, it is imperative to explore the mechanical properties and underlying mechanisms of 2D materials. However, researchers have an inadequate understanding of the accuracy of various in situ microscopy techniques and neglect the significance of high-quality, clean transfer techniques, resulting in deviated measurement results. There is now an urgent need to develop guidelines that allow researchers to select appropriate material transfer techniques and mechanical testing strategies based on the specific properties of 2D materials. Furthermore, the mechanical mechanism of 2D materials lacks systematic and comprehensive studies, which hinders researchers from deeply understanding the relationship between the material structure and the device performance. This work reviews the latest progress in the mechanics of 2D materials, focusing on the challenges of various transfer techniques and in situ microscopy techniques in mechanical testing, and provides effective guidance for the formulation of experimental schemes for mechanical testing. In addition, we offer detailed mechanistic insights into the fracture behavior, geometric dimension effects, edge defects, and interlayer bonding effects of 2D materials. This work is expected to advance the field development of 2D material mechanics.