나일론 시트와 염료를 이용한 고감도 색변환 포름알데히드 가스 센서

Abstract

A colorimetric sensor was investigated to achieve a low-cost warning device for harmful gaseous formaldehyde (HCHO). The sensor is based on selective reactions between hydroxylamine sulfate and HCHO, leading to the production of sulfuric acid. The produced acid results in color-changing response through the acid-base reaction with dye molecules impregnated on a solid membrane substrate. For attaining this purpose, sensors were fabricated by drop-casting a dye solution prepared using different pH indicators on various commercially available polymer sheets, and their colorimetric responses were eval- uated in terms of sensitivity and reliability. The colorimetric sensor using bromophenol blue (BPB) and nylon sheet was found to exhibit the best performance in HCHO detection. An initial bluish green of a sensor was changed to yellow when exposed to gaseous formaldehyde. The color change was recorded using an office scanner and further analyzed in term of RGB distance for quantifying sensor’s response at different HCHO(g) concentrations. It exhibited a recognizable col-orimetric response even at 50 ppb, being lower than WHO’s standard of 80 ppb. In addition, the sensor was found to havequite good selectivity in HCHO detection under the presence of common volatile organic compounds such as ethanol, tol- uene, and hexane.