True FRET-based sensing of pH via Separation of FRET and Photon Reabsorption.

Förster Resonance Energy Transfer (FRET)-based devices have been extensively researched as potential biosensors due to their highly localized responsivity. In particular, dye-conjugated upconverting nanoparticles (UCNPs) are among the most promising FRET-based sensor candidates. UCNPs have a multi-modal emission profile that allows for ratiometric sensing, and by conjugating a biosensitive dye to their surface, this profile can be used to measure localized variations in biological parameters.

Selective enhancement of upconversion luminescence for enhanced ratiometric sensing.

Lanthanide-doped upconversion nanoparticles (UCNPs) have attracted widespread interest in bioimaging and sensing due to their photostability, low excitation energy, and good tissue penetration. Plasmonic nanostructures, on the other hand, can enhance the luminescence of UCNPs by concentrating electric fields into a nanoscale volume. While the enhanced luminescence intensity is in principle beneficial to sensing, intensity-based sensing has limitations in absolute measurements.

Over 1000-fold enhancement of upconversion luminescence using water-dispersible metal-insulator-metal nanostructures.

Rare-earth activated upconversion nanoparticles (UCNPs) are receiving renewed attention for use in bioimaging due to their exceptional photostability and low cytotoxicity. Often, these nanoparticles are attached to plasmonic nanostructures to enhance their photoluminescence (PL) emission. However, current wet-chemistry techniques suffer from large inhomogeneity and thus low enhancement is achieved.

Direct modeling of near field thermal radiation in a metamaterial.

The study of near field thermal radiation is gaining renewed interest thanks in part to their great potential in energy harvesting applications. It is well known that plasmonic or polaritonic materials exhibit strongly enhanced fields near the surface, but it is not trivial to quantitatively predict their impact on thermal radiation intensity in the near field. In this paper, we present a case study for a metamaterial that supports a surface plasmon mode in the terahertz region and consequently exhibits strongly enhanced near field thermal radiation at the plasmon resonance frequency.