Graphene/Polyaniline Film Optical Fiber Ammonia Gas Sensor With Excellent Sensing Performance

The possibility to improve the detection index of the optical ammonia (NH $_{{3}}{)}$ gas sensors based on the graphene/polyaniline (graphene/PANI)-coated Mach–Zehnder interferometric optical fiber structure with etched thin core fiber (e-TCF) is investigated. Based on the analysis of the output wavelength, a significant increase in sensitivity and stability of the NH₃ sensors is achieved by using TCF. The experimental results show that its sensitivity is −27.8 pm/ppm, the response time is 32 s, the dip wavelength error is lower than ±0.02 nm, and the dip intensity error is lower than ±0.002 dB in the stability test. This article illustrates that the proposed sensor has numerous advantages, including small size, strong antielectromagnetic interference, and excellent repeatability characteristics. Furthermore, it can be applied in biomedical detection applications as it can improve the detection resolution of NH₃ concentration at room temperature.