Sensitive Films for Optical Detection of Ammonia and Nitrogen Dioxide

Abstract

The sol-gel technology allows preparation of the thin silica lms ranging in porosity from dense to highly porous. These lms can function as matrix binding molecules of pH-sensitive indicators and can be utilized as sensitive coatings for intensity based planar evanescent wave chemical sensors. This paper is devoted to manufacturing technology and characterization of highly porous silica lms deposited on soda-lime glass substrates, impregnated with bromocresole purple and cresole red. Two dierent methods of impregnation were used: dip coating, which entails sensitization of both silica lms deposited on each side of a substrate and selective deposition of a dye solution on single side of the substrate. Manufactured sensitive lms were tested toward inuence of gaseous ammonia and nitrogen dioxide on their spectral characteristics of the absorption coecient and the imaginary part of the refractive index. It was shown that bromocresole purple allows detection of both gases: NH3 and NO2.

MMI Structures Covered by Bromocresol Purple for Ammonia Detection

“…The distribution prole of refractive index of MMI section obtained in the diusion process is calculated numerically from the nonlinear diusion equation [9].…”

The sensitivity of sensor structures with oxide graphene exposed to selected gaseous atmospheres

“…Another gas, which needs special attention is nitrogen dioxide, particularly its monitoring occurs in large agglomerations. NO 2 is very harmful for the human health, and its presence in the atmosphere contributes to dangerous environmental pollution [6].…”

Sol-gel Materials with Silver Nanoparticles for Simultaneous Concentration and Detection of Substances by SERS

“…Золь-гель (З-Г) технология является перспективным методом для получения наноразмерных композитных материалов, например просветляющих покрытий [1], неподвижных фаз для хроматографии [2], чувствительных покрытий сенсоров [3,4], сорбентов для твердофазной экстракции [5] и т.п. З-Г материалы сочетают в себе такие преимущества, как высокоразвитая поверхность, способность эффективно сорбировать химические соединения, химическая стойкость и физическая прочность.…”