Oxygen sensing using a strongly coupled bio-plasmonic system

Plasmonics has been successfully used for a couple of decades for biosensing. In particular, the sensitivity of surface plasmon-polaritons propagating on a metal thin film to their immediate environment is routinely used to monitor binding reactions in bioassays. In this technology however, there is no coupling between the surface plasmon and optical resonances occurring in the analyte. Here, we demonstrate that strong coupling between the plasmonic system and the analyte can dramatically enhance the sensitivity of plasmonic biosensing. Specifically, we investigate theoretically the strong coupling between surface plasmon resonances and absorption bands of hemoglobin. When the surface plasmon resonance spectrally overlaps the absorption bands of hemoglobin, the system is strongly coupled and its dispersion diagram exhibits an anti-crossing. Working in the conditions of strong coupling enhances the sensitivity of a surface plasmon sensor up to a factor of 10. A model for the permittivity of hemoglobin, both in oxygenated and deoxygenated states, is presented and the study is carried out for both angle and wavelength modulated SPR sensors.

Biosensing of oxygen content using the strong coupling between a surface plasmon-polariton and the absorbtion bands of hemoglobin. Two different states are considerated for the analyte: (a) fully oxygenated and (b) de-oxygenated.

Check the corresponding publication: PDF External link: doi: 10.1063/1.3626786