A paper-based sensor capable of differentiating ammonia and carbon dioxide gas

Abstract

Selective and rapid detection of ammonia gas over a wide concentration range is of great importance in many applications such as medical diagnostics and assessing perishable food quality and safety. One of the major obstacles in detection of ammonia is the selectivity and inhibiting the effect of other interfering gases such as carbon dioxide. In this work, we present a polystyrene sulfonate (PSS) coated paper-based sensor as an efficient multi-functional system for detection and differentiation of ammonia from carbon dioxide at high humidity levels ( > 85%) with distinctive resistivity behaviour. This sensor’s resistivity increases in the presence of CO2 and decreases drastically in the presence of NH3 gas, due to interaction with the PSS functional group. The sensor can selectively measure ammonia in the presence of other volatile organic compounds/gases. A linear correlation is observed between resistance and ammonia concentration with a broad range of detection from 0.25 ppm to 2500 ppm. This is remarkably superior to other commercially available sensor with a narrow range of detection from 1 ppm to 100 ppm. In addition, the sensor can monitor meat spoilage in real time at different temperatures (23 ℃ and 4 ℃). Therefore, this disposable paper-based polystyrene sulfonate sensor has high potential for developing a low-cost and portable device for medical diagnostics and determining perishable food quality and safety.