Abstract

In this study, we report an NH3 gas sensor based on highly porous single layered graphene assembled porous carbon (SLGAPC) coated optical fiber operating in Fabry-Perot interferometric (FPI) mode. The sensor tip, which was the mirror end of the interferometer, was prepared using dip coating technique. The response of the sensor in terms of wavelength shift was recorded on to Optical Sensing Analyzer (OSA) in presence of ammonia gas. The gas concentration was varied from 1.5 ppm to 240 ppm at room temperature. It was observed that SLGAPC was very sensitive to ammonia due to its very high porosity and high conductivity. The adsorption of ammonia molecules on porous graphene modifies the refractive index and thus the output signal in terms of wavelength shift of an interferometer. The FPI showed high wavelength shift of 4.85 nm for 240 ppm ammonia concentration. The sensor showed rapid response and recovery time (of the order of few seconds). The sensor showed sensitivity ~ 20 pm/ppm, with resolution obtained in the ppb range, limited due to the resolution of OSA used. The sensor based on highly porous graphene with high sensitivity, fast response and recovery time, simple fabrication, and low cost is a potential candidate for development of novel gas sensors.