Real-Time Detection of Gas and Chemical Vapor Flows by Silica Inverse-Opals

A silica inverse-opal is fabricated through the co-assembly of silica precursors and mono-dispersed polystyrene particles with a diameter of 287 nm. Then, the polymer face-centered-cubic structure was removed by calcination procedure to obtain a silica inverse-opal offering sharp stop-band around 445 nm. Sensitivity of the sample for static refractive index detection was acquired by its immersion in different water/ethanol mixtures. Furthermore, an experimental setup was designed to evaluate the dynamic response of sample for diverse gas and water vapor flows. Fabricated sample is capable of offering high sensitivities as high as 415 nm/RIU and reversible responsivities as fast as 120 ms. Also, it has been shown that despite reduced sensitivity in dynamic measurements, fabricated silica inverse-opal is able to detect slight refractive index variations and thus very small alterations in gas and vapor flows. According to which, the proposed structure may find numerous applications in remote and non-destructive gas and vapor flow sensing.