Polymer transduction cavity based optical fiber Fabry-Perot interferometer for VOC sensing

Frequent exposure to volatile organic compounds (VOC) above the permissible limit can result in adverse health effects. Therefore, VOC detection and monitoring at trace levels are essential in both indoor and outdoor environments. A highly sensitive and accurate method is desired for this purpose and optical interferometry is a sensitive measurement technique useful for trace-level VOC sensing. We have fabricated and experimentally studied the sensing properties of the optical fiber Fabry–Perot interferometer polymer sensor cast on the fiber tip for acetone detection. Polystyrene, deposited at the end facet of the fiber act as the FP cavity. A significant shift in the interference pattern resonant dip positions is observed in the interaction of the FP cavity with acetone vapor due to changes in the properties of the polymer resulting in physical thickness variation and a change in refractive index. Emphasis has been put on studying the sensor performance over multiple measurement cycles to affirm the reproducibility of the results for repeated usage instead of one-time disposable measurements. Excellent repeatable sensing performance with a sensitivity of 5.78 pm/ppm is observed for 09 data sets recorded over 09 days consisting of 190 individual experimental studies.