Development of a smartphone-based real time cost-effective VOC sensor

Air pollution by various volatile organic compounds (VOC) is a matter of concern for us. So in this regard, designing real-time VOC responsive materials is gaining attention across the scientific community. In this present work, we have developed an inexpensive VOC sensor based on a Meisenheimer complex derived from picric acid and N,N'-dicyclohexylcarbodiimide. The sensor coated TLC plate was used as a sensor of potentially harmful VOCs. The sensor coated TLC plate looks deep red colored and does not show any fluorescence emission under 366 nm UV light. But in the presence of harmful volatile organic compounds like benzene, toluene, xylene, etc the sensor coated TLC plate becomes orange colored and it also shows strong yellow emission under 366 nm UV light. This property was utilized to detect the VOCs by fluorescence spectroscopy. The detection limit for various VOCs was found to be in the range of 0.7-9 ppm. To make the sensor user friendly, we have demonstrated a method where VOCs can be detected using a smartphone in real-time and also the setup is portable.