Mechanical, Elastic, and Adhesive Properties of Two-Dimensional Materials: From Straining Techniques to State-of-the-Art Local Probe Measurements

2D materials, such as graphene, hexagonal boron nitride (hBN), and transition-metal dichalcogenides (TMDs), are intrinsically flexible, can withstand very large strains (>10% lattice deformations), and their optoelectronic properties display a clear and distinctive response to an applied stress. As such, they are uniquely positioned both for the investigation of the effects of mechanical deformations on solid-state systems and for the exploitation of these effects in innovative devices. For example, 2D materials can be easily employed to transduce nanometric mechanical deformations into, e.g., clearly detectable electrical signals, thus enabling the fabrication of high-performance sensors; just as easily, however, external stresses can be used as a knob to dynamically control the properties of 2D materials, thereby leading to the realization of strain-tuneable, fully reconfigurable devices. Here, the main methods are reviewed to induce and characterize, at the nm level, mechanical deformations in 2D materials. After presenting the latest results concerning the mechanical, elastic, and adhesive properties of these unique systems, one of their most promising applications is briefly discussed: the realization of nano-electromechanical systems based on vibrating 2D membranes, potentially capable of operating at high frequencies (>100 MHz) and over a large dynamic range.

Automated summary

2D materials, such as graphene and hBN, have unique properties that allow them to withstand large strains and respond to applied stress. This makes them ideal for investigating mechanical deformations in solid-state systems and developing innovative devices. These materials can be used to transduce nanoscale mechanical deformations into detectable electrical signals, enabling the fabrication of high-performance sensors. Additionally, external stresses can be used to dynamically control the properties of 2D materials, leading to the development of strain-tuneable, fully reconfigurable devices. This review also discusses the potential application of vibrating 2D membranes in nano-electromechanical systems that operate at high frequencies and over a large dynamic range.