A Novel Trace-Level Ammonia Gas Sensing Based on Flexible PAni-CoFe(2)O(4) Nanocomposite Film at Room Temperature

In this study, we developed a new chemi-resistive, flexible and selective ammonia (NH(3)) gas sensor. The sensor was prepared by depositing thin film of polyaniline-cobalt ferrite (PAni-CoFe(2)O(4)) nanocomposite on flexible polyethylene terephthalate (PET) through an in situ chemical oxidative polymerization method. The prepared PAni-CoFe(2)O(4) nanocomposite and flexible PET-PAni-CoFe(2)O(4) sensor were evaluated for their thermal stability, surface morphology and materials composition. The response to NH(3) gas of the developed sensor was examined thoroughly in the range of 1–50 ppm at room temperature. The sensor with 50 wt% CoFe(2)O(4) NPs content showed an optimum selectivity to NH(3) molecules, with a 118.3% response towards 50 ppm in 24.3 s response time. Furthermore, the sensor showed good reproducibility, ultra-low detection limit (25 ppb) and excellent flexibility. In addition, the relative humidity effect on the sensor performance was investigated. Consequently, the flexible PET-PAni-CoFe(2)O(4) sensor is a promising candidate for trace-level on-site sensing of NH(3) in wearable electronic or portable devices.