Room temperature detection of chemical pollutants by SnO2-based optical fiber sensors

In the last decade a huge number of SnO2-based gas sensors have been proposed for environmental monitoring, automotive applications, air conditioning in houses, airplane and aircrafts. However, most of the proposed sensors work at very high temperatures in order to reach high sensitivities. Here, a SnO2-based optical fiber sensor is proposed for the room temperature detection of chemical pollutants in air. Particles layers composed by tin dioxide grains, with wavelength and subwavelength dimensions, resulted very promising because they are able to significantly modify the optical near field profile emerging from the film surface due to local enhancements of the evanescent wave contribute, and thus to improve the sensitivity to surface effects induced by the analyte interaction. The room temperature sensing performances of SnO2-based particles layers towards environmental pollutants have been investigated by the exposure to different concentrations of toluene and xylene vapors as well as gaseous ammonia. They have also been compared with the performances obtained with other optical fiber sensors in the same configuration, but coated with different sensitive materials, such as Single-Walled carbon nanotubes. The preliminary results obtained evidenced the surprising capability of the SnO2-based optical sensor to detect chemical pollutants at ppm level in air at room temperature. Finally, preliminary results on the effects of the processing parameters and post processing thermal annealing on film morphology and optical near field are presented.