Optical chemo-sensor based on long period gratings coated with δ form syndiotactic polystyrene

In this work, a long period grating (LPG) is coated with a thin film of syndiotactic polystyrene (sPS) in the nanoporous crystalline δ form in order to obtain a species-specific chemical sensor. The combination of the intrinsic and high refractive index sensitivity of the LPGs with the high sorption properties toward chlorinated and aromatic compounds of sPS δ form allows detecting very low concentrations (in the range of few parts per million) of chloroform in water. Chemical detection is carried out by measuring the wavelength shift and the amplitude changes in the attenuation band of the LPG due to analyte sorption.