Suspended Graphene Membranes for Strain Sensor Applications

Abstract

CVD monolayer graphene cavities based devices were fabricated and characterized along with non-cavity devices as a differential pair of sensors for strain detection. The cavities were etched into SiO2 over Si substrate and then graphene films were transferred forming the graphene membrane over the cavities. Raman spectroscopy of graphene on top of cavities showed significant redshift in the 2D band vs. non cavity device $(0.14\ \mathbf{c}\bar{\mathbf{m}}^{1}$ per $1\mu\mathbf{m}$ of cavity diameter), which is due to the elongation of the carbon-carbon bonds. This indicates the feasibility of using graphene membrane as a strain sensor. The gauge factor defined as the relation between the change in electrical resistance and the induced strain was computed to be equal to 4.11. This sensor was tested in gas environment. The cavity shows a higher sensitivity than the non-cavity as a function of the gas introduced. These results indicates that the induced strain within the cavity in graphene is key enabler for the added sensitivity for graphene based sensor system.