Electromechanical Pressure Sensing of Suspended Graphene Membranes with Different Atomic Layers

Graphene is one of the promising materials for sensing pressure due to its atomically thin thickness and excellent electrical and mechanical properties. Pressure sensors based on suspended graphene membranes with different thicknesses are expected to have improved device performances, which have not been studied yet. Here, nanoelectromechanical pressure sensors based on suspended monolayer, bilayer, and trilayer graphene membranes were realized. The monolayer graphene-based pressure sensor features the highest sensitivity (1.65 × 10^-4 kPa^-1) among different types of prepared graphene devices. Further, the normalized sensitivity per area of suspended graphene membranes of monolayer graphene-based pressure sensor (1.67 × 10^-6 kPa^-1 μm^-2) is higher than previously reported graphene-based pressure sensors. However, the trilayer graphene membrane-based pressure sensor features excellent stability (resistance drift of about 0.02%) and durability in the process of the long-time pressure maintenance measurements. Based on the experimental results, simulations of graphene pressure sensors based on different numbers of atomic layers were performed to estimate the deflections, strains, and piezoresistive gauge factors of suspended graphene membranes. These findings would contribute to understanding of properties of suspended graphene membranes and development of ultrasmall and high-performance pressure sensors based on 2D membranes.