Blister test to measure the out-of-plane shear modulus of few-layer graphene

We measure the out-of-plane shear modulus of few-layer graphene (FLG) by a blister test. During the test, we employed a monolayer molybdenum disulfide (MoS₂) membrane stacked onto FLG wells to facilitate the separation of FLG from the silicon oxide (SiO_<i>x</i>) substrate. Using the deflection profile of the blister, we determine an average shear modulus <i>G</i> of 0.97 ± 0.15 GPa, and a free energy model incorporating the interfacial shear force is developed to calculate the adhesion energy between FLG and SiO_<i>x</i> substrate. The experimental protocol can be extended to other two-dimensional (2D) materials and layered structures (LS) made from other materials (WS₂, hBN, <i>etc</i>.) to characterize their interlayer interactions. These results provide valuable insight into the mechanics of 2D nano devices which is important in designing more complex flexible electronic devices and nanoelectromechanical systems.