Xiangyang Gao's research while affiliated with Beihang University (BUAA) and other places

Waals adhesion behavior at the interface between graphene and support substrates is important to characterize the performance of graphene-based sensors. Here an improved, general, and direct method of determining the adhesion energies of monolayer/few-layer/multilayer graphene sheets on silicon wafers is demonstrated by measuring the debonding radius of axisymmetric blisters loaded with both one and two nanoparticles. Along with the established model for large deflection of circular membranes trapping nanoparticles at graphene–silicon interface, the adhesion energies for monolayer, 3–5 layer, and 10–15 layer graphene membranes are obtained as 0.453 J m–2, 0.317 J m–2, and 0.276 J m–2, respectively, which conform exceedingly well to the previously measured results. This presented method can be further extended to measure adhesion energies between other 2D materials and various substrates.

A miniature Fabry–Perot interferometric acoustic sensor with an ultra-high pressure sensitivity was constructed by using approximately 13 layers of graphene film as the diaphragm. The extremely thin diaphragm was transferred onto the endface of a ferrule, which had an inner diameter of 125 μm, and van der Waals interactions between the graphene diaphragm and its substrate created a low finesse Fabry–Perot interferometer with a cavity length of 98 μm. Acoustic testing demonstrated a pressure-induced deflection of 2380 nm kPa−1 and a noise equivalent acoustic signal level of ~2.7 mPa/Hz1/2 for a 3 dB bandwidth with a center frequency of 15 kHz. The sensor also exhibited a dynamic frequency response between 1 and 20 kHz, which conformed well to the result obtained by a reference microphone. The use of a suspended graphene diaphragm has potential applications in highly sensitive pressure/acoustic sensors.