A porous glass-based KI/α-CD chip for ozone sensing: Improvement in the humidity response of the chip through optimizing reagent concentrations in the impregnation process

Abstract

To improve the performance of our previously-reported KI/α-CD ozone sensing chip, the present work carried out a series of experiments based on exposing these chips to ozone under static conditions. This device was confirmed to operate on a passive principle by monitoring the absorption at 360 nm due to the formation of a clathrate complex of α-CD with triiodide ions generated by the reaction of O3 with KI on a porous glass surface. The sensing capabilities of chips fabricated under different conditions were evaluated by plotting absorbance at 360 nm against total ozone exposure, and KI and α-CD concentrations of 104 and 19.4 mM, respectively, in the immersion solution employed during fabrication were found to be optimal. The data also show that chips prepared by immersion in this solution are as sensitive (based on a 3 ppb limit of detection with a 1 h exposure) at 90% RH as the previously-reported units, and that the performance of the present chips is unchanged over the RH range of 37% to 80%.