A Polymer-Based Chemiresistive Gas Sensor for Selective Detection of Ammonia Gas

Breath analysis is a non-invasive tool used in medical diagnosis. However, the current generation of breath analyzers is expensive, time-consuming, and requires sample gas separation. In this work, a simple, yet effective, low-cost ammonia gas sensor based on poly(2-acrylamido-2-methyl-1-propanesulfonic acid) is presented for non-invasive medical diagnosis. The designed sensor has a broad detection range to ammonia gas up to 1000 ppm with a limit of detection of 30 ppb. This is a robust sensor, which functions at high relative humidity (RH) (>90%) and exhibits consistent electrical responses under different test conditions. The result of a blind test validates the sensor’s selective response to ammonia in the presence of other gases such as carbon dioxide. Furthermore, it is viable to integrate this sensor into a mask for real-time ammonia gas detection accurately. Overall, this study demonstrates the feasibility of developing a simple, non-invasive, and cost-effective sensor for real-time monitoring of ammonia gas with high potential in applications such as medical diagnostics, food safety, and environmental conditions.