Evaluation of air quality with simple and easy chemical sensors: Development of porous glass-based elements

The authors are tackling the development of novel chemical sensor elements for detecting air pollutants. The base material of the sensor elements is porous glass, which has favorable features such as transparency and porosity. The sensor elements were prepared by impregnating reagents in a sheet of porous glass. The reagents were the Saltzman reagent for the detection of nitrogen dioxide, beta-diketones for formaldehyde and potassium iodide for oxidant. The resultant elements were colorless. The first element was highly sensitive and changed to clear wine red upon exposures to nitrogen dioxide. The second element for formaldehyde developed yellow and was detectable as low as a few tens ppb for an exposure time of 8 h. The third element for oxidant also showed high sensitivity. Evaluation of the effects of various gases on these elements, which are indispensable in applying them to the real atmosphere, is underway except for the NO₂ elements. The concept leading to the present study is briefly explained.