Pyridine vapors detection by an optical fibre sensor

An optical fibre sensor has been implemented towards pyridine vapors detection; to achieve this, a novel vapochromic material has been used, which, in solid state, suffers a change in colour from blue to pink-white in presence of pyridine vapours. This complex is added to a solution of PVC (Poly Vinyl Chloride), TBP (Tributylphosphate) and tetrahydrofuran (THF), forming a plasticized matrix; by dip coating technique, the sensing material is fixed onto a cleaved ended optical fibre. The fabrication process was optimized in terms of number of dips and dipping speed, evaluating the final devices by dynamic range. Employing a reflection set up, the absorbance spectra and changes in the reflected optical power of the sensors were registered to determine their response. A linear relation between optical power versus vapor concentration was obtained, with a detection limit of 1 ppm (v/v).