Humidity Tolerant Sub-PPM Ammonia Gas Sensors

Accurate ammonia detection is critical for areas such as environmental monitoring, medical diagnostics, and industrial safety. Existing commercial gas sensors struggle with poor sensitivity, selectivity, and stability, especially in a fluctuating humidity environment. Despite significant advancements in the sensitivity of ammonia gas sensors in research, their performance in varying environmental conditions leaves much to be desired. This review explores the recent progress of electrical, gravimetric, and optical sub-ppm ammonia gas sensors and their humidity tolerance at room temperature. By considering the humidity interference mechanism, strategies to alleviate its impact are discussed. Through these strategies, it is imperative to balance sensitivity and stability in sensor design to enhance the commercial deployment of these solutions in an array of applications.