3D Graphene-Based Optical Sensors

Abstract

3D graphene (3DG) has been utilized as a functional material for the development of gas and chemical sensors. The sensor based on optical phenomena such as surface plasmon resonance (SPR) offers label-free measurements at a very high resolution and sensitivity. It is essential for any sensor to exhibit a very high analyte adsorption capability and good perceptibility to measure changes in electrical and optical properties due to such adsorption. Although SPR is extremely sensitive, 3DG is one of the potential functional materials which can exhibit a high analyte adsorption capability. Therefore, the use of 3DG as a functional layer in SPR devices can ensure a next-generation sensor. The Kretschmann configuration in angular interrogation-based SPR sensors may offer a sensitivity of the order of 10–8 RIU. In the SPR sensor, the extent of the plasmonic field over the metallic surface is limited to a few hundred nanometres. The excellent adsorption capability of 3D graphene can be employed for bio-sensing applications. However, due to the bulk nature of 3DG, the plasmonic field during SPR-based sensing decays rapidly into the porous structure of the 3DG, and therefore, the measurement becomes unresponsive even after the efficient adsorption of the analytes. Therefore, the layer of 3D graphene can be grown over the gold surface by some bottom-up deposition mechanism with control over the thickness. The bottom-up deposition mechanism may yield monolayer, bilayer, and twisted bilayer graphene which also exhibit excellent bio-sensing merits.