We use graphene as a new enabling two-dimensional material to improve the versatility and sensitivity of infrared vibrational spectroscopy systems and sensors.
Graphene sustains long-lived electron oscillation in the mid-infrared region of the spectrum. By patterning graphene nano-structures, such as nano-ribbons or nano-disks, we can couple infrared light to plasmonic resonances. The high fields in the vicinity of the graphene nano-structures enhances the interaction with biomolecules and enables high-sensitivity detection.
We are exploiting the unique properties of graphene plasmonic resonances to develop novel infrared biosensors with extended functionalities. Two examples of the new possibilities offered by graphene infrared biosensor are mentioned below:
- Extreme light confinement:Graphene plasmonic modes show a level of field confinement up to two orders of magnitude higher than that obtained with noble metals. This enables high sensitivity vibrational spectroscopy and at the same time allows to perform refractive-index based sensing, so far a prerrogative of visible-range sensors.
- Reconfigurable sensors: The plasmonic resonances of graphene can be tuned through voltage control. We are able to dynamically scan the graphene plasmonic resonances over a large spectral range to be able to probe the analyte at different frequencies, in particular being able to selectively amplify different vibrational modes of a biomolecule.
Tunable Graphene Nanostructures for Plasmon-Enhanced Infrared Spectroscopy
D. Rodrigo, O. Limaj, D. Janner, D. Etezadi, F.J. García-de-Abajo, V. Pruneri and H. Altug, “Mid-infrared Plasmonic Biosensing with Graphene“, Science 349 (2015).