Development of Formaldehyde Gas Sensor that Exhibits Distinct Color Changes

A new type of colorimetric sensor that detects formaldehyde in air was developed. The sensor consists of a thin film containing primary amino groups on a glass substrate. After exposure to gaseous formaldehyde, the thin film was immersed in an aqueous solution containing an anionic dye. The color of the thin film distinctly changed in accordance with the formaldehyde concentration in air. It was found that the sensitivity of this sensor is significantly affected by factors such as the exposure time, the humidity of air, and the monomer composition of the thin film.