Surface label-free sensing by means of a fluorescent multilayered photonic structure

A fluorescent dielectric multilayer is exploited for label-free sensing in aqueous microenvironment. Fluorescence is laser-excited and collected through prism-coupling to a surface electromagnetic mode, also known as Bloch surface waves (BSW) localized at the interface between the multilayer and the outer aqueous medium. By detecting the spectral changes of the BSW-coupled light emission due to an external perturbation of the refractive index (Dn), a sensitivity of 2500 nm/RIU and a limit of detection down to Dn=3 10^-6 are obtaine