Graphene is a novel two-dimensional material composed of a one-atom-thick planar sheet of sp2-bonded carbon atoms perfectly arranged in a honeycomb lattice that has exceptional photonic and electronic properties. We believe that the true potential of graphene lies in optical sensors, especially for biochemical sensing in the diagnostics and health care sector. Graphene has extraordinary properties, such as a one-atom thickness, extremely high surface-to-volume ratio, large surface area, ability to quench fluorescence, excellent biocompatibility, broadband light absorption, ultrafast response time, high mechanical strength, outstanding robustness, and flexibility. The working principle is based on whenever the biomolecules come into contact with graphene, the Fermi level shifts to either p-type or n-type, changing the opto-electronic properties. The most important factors in graphene-based optical sensing are lowering the limit of detection and increasing the specificity of label-free biochemical sensing. This article comprehensively and critically reviews emerging graphene optical biochemical sensors. We first elaborate on their opto-electronic properties, fabrication, numerical modeling and simulation, and then review various sensing applications, such as single-cell detection, neural imaging and optogenetics, colorimetric multifunctional sensors, cancer diagnosis, protein and DNA sensing, and gas sensing. Finally, the roadmap of current and future trends in graphene-based optical biochemical sensors is discussed.
- optical sensors