Chitin-Based Functional Films for the Colorimetric Detection of Ethylene Glycol

A new method is developed for producing large-area color thin films for the colorimetric detection of ethylene glycol. This method is based on thermal evaporation of chitin. This process enables easy manipulation of the thickness and color patterns of the film by using shadow masks and repeated evaporation. This film is used to demonstrate a colorimetric sensor for the detection of ethylene glycol gas. The use of chitin allows the manufacture of inexpensive and environment-friendly gas detectors. When the film is exposed to target gas, the film reacts with ethylene glycol and hydroxyl group on the chitin-film by etherification. Then the films undergo both chemical and structural changes, resulting in color changes at low ppm concentrations. It is able to compare the sensor reaction to gases with and without the hydroxyl group. The selectivity of the sensor is confirmed by analyzing the gas containing the hydroxyl group through the linear discriminant analysis (LDA) method. It is expected that the results will be utilized to provide low-cost and low-power systems for gas monitoring.