Fluorescent gas sensors based on nanoporous optical resonators (microcavities) infiltrated with sensory emissive polymers

In this contribution we report fluorescent gas chemosensors for detection of nitroaromatic vapors and other classes of volatile organic compounds based on porous silicon (PSi) microcavity (MC) infiltrated with sensory emissive polymers. Such hybrid functional sensors have several advantages over traditional fluorescent chemosensors, where the sensory polymers are deposited on flat substrate. This includes a high interfacial area of nanoporous Si (high sensitivity), narrow fluorescent band due to photon confinement, dependence of the spectral peak position on nature of analyte (enhanced selectivity), and fast recovery time. We demonstrated that deep and uniform polymer infiltration is critical for effective gas sensing and investigated the experimental conditions required for preparation of high quality hybrid sensors. In the case of deep infiltration, the broad polymer fluorescence (FWHM ~ 100 nm) shows a narrowing to the resonance peak (FWHM ~ 10 nm) with narrow intensity angle diagram. In addition, the potential of the sensor array platform and sensor recovery under ultrasound power is discussed.