Optical fiber sensor for the vapor phase detection of Trifluoroethanol

Abstract

A sensing probe is presented for the detection of 2,2,2-trifluoroethanol in the vapor phase, while using poly(vinylidene fluoride (PVDF) thin films, overlaid onto tilted optical fiber Bragg gratings. The 2,2,2-trifluoroethanol sensor operates in the 1.5 μm band, in transmission mode, where the signal of both the core and cladding modes is monitored. Best detectivities obtained are 2 ppm for 2,2,2-trifluoroethanol vapors in ambient atmosphere, for typical response times of 50 min. The sensing probe presented - based on PVDF transductor - shows limited reversibility after being used in the tracing of 2,2,2-trifluoroethanol vapors; its subsequent exposure to nitrogen flow, partly reverses its spectral behavior back to the starting point, denoting the involvement of mechanisms other than physisorption into the underlying transduction. The actual sensing mechanism of 2,2,2-trifluoroethanol vapors while using thin PVDF films is currently under investigation.