Mid-infrared biosensing with tunable graphene plasmons

Mid-Infrared (mid-IR) spectroscopy has been widely used to identify biomolecules. Due to the general poor interaction of mid-IR light with nanometric-scale molecules, the electro-optical properties of graphene resonant plasmons based device is exploited to demonstrate a tunable label-free protein sensor with high sensitivity. The confinement of graphene plasmons is much larger than that of the conventional metallic structure due to the two-dimensional nature of the collective oscillations of Dirac quasi-particles. The localized graphene plasmons can dynamically produce a high light overlap with nanometer size biomolecules, which plays an essential role in the resulted super sensitivity in the detection of the protein's permittivity. Furthermore, graphene plasmons merge optics with electronics which provide a unique capacity to control light in nanoscale. Tunable resonant spectra selectivity combined with the super ambient condition sensitivity promise the graphene plasmons based device exciting prospects in future nanoscale biosensing.