Multi-variable micro opto-fluidic ring resonator sensing with plasmonic nanoparticle films

Localized surface plasmon resonance (LSPR) in films of thiolate- and dithianate-monolayer-protected gold nanoparticles (MPN) having different monolayers and Au core sizes (4, 5, and 40 nm), and probed at three visible wavelengths near the LSPR maximum, has been exploited to discriminate among 6 vapors with a single sensing film. Arrays of just two MPN films (4- or 5-nm core diameters) were also remarkably selective (> 95% discrimination) even probing each film with just a single wavelength. Initial results obtained from the first MPN-coated microfabricated optofluidic ring resonator sensor (μOFRR) used as a μGC detector are also presented and appear promising.