The application of the phase transition in nematic liquid crystals for the optical detection of volatile organic compounds

It is demonstrated that optical transducers can take advantage from the outstanding optical properties of nematic liquid crystals. The measurements point out that the birefringence and the phase transition of a liquid crystal can be exploited for the threshold sensing. For that purpose a device consisting of an orientated liquid crystalline film between two crossed polarizers was used. The nematic liquid crystal was also used as a sensitive coating material on an integrated optical Mach-Zehnder interferometer. The calibration experiments were carried out with volatile organic solvents and different calibration curves were measured for meta-xylene and para-xylene.