SPR fibre sensor sensitised by fluorosiloxane polymers

A simple SPR optical fibre sensor working with a monochromatic light source and based on resonance in a stabilised silver film is presented here. It can be used either as an optical fibre refractometer, in the range of refractive index: 1.355–1.405 with a sensitivity of 4.5×10−5, or as a chemical vapour sensor. For the detection of vapours of chlorinated hydrocarbon compounds and of aromatic compounds, the sensitive part of the fibre is coated with fluorosiloxane polymers. Detection limits of 3000 ppm were obtained for trichloroethylene and of 180 ppm for xylene. The sensitivities of detection of the optical fibre sensor coated with fluorosiloxane polymers are discussed. For the chlorinated hydrocarbon compounds, the difference between the refractive indices of the solvent and the polymer is the predominant factor. For aromatic compounds whose boiling temperature is higher, the condensation effect in the porosity of the polymer is predominant.