Fabrication and characterization of NO2 gas sensor based on one dimensional photonic crystal for measurement of air pollution index

We have fabricated the corresponding photonic crystal (PC) structure by means of electron beam evaporation in a sample chamber at a pressure of 10^-3Pa with BK-7 glass substrate at temperatures of 573K. This PC device is applied as a sensor to detect the concentration of NO₂ gas dissolved in specific reagent Griess Saltzmann. From spectroscopic measurement it is found that the absorption spectral of the NO₂ gas to be in the range of light source wavelength 500-550 nm. Based on this fact, we set up the PCs to admit a photonic pass band (PPB) at a wavelength of 550 nm. To enhance the performance, the device is designed to work on the basis of both absorption and PPB variation phenomena. The experimental results show that the response of the device correlates linearly with the concentration of dissolved NO₂ gas and exhibits high sensitivity with coefficient determination of 99%. This sensor is potential to apply in an air pollution index measurement system.