Performance of fiber Bragg grating hydrogen sensor coated with Pt-loaded WO3 coating

Pt-loaded WO3 coatings with different constitutes were prepared by Sol-Gel method and deposited on fiber Bragg gratings (FBG) with enhanced temperature sensitivity. The composition, structure and micro morphology of Pt-loaded WO3 coating were investigated by energy dispersive X-ray analysis (EDAX), X-ray diffraction (XRD) and scanning electron microscopy (SEM). Experimental results show that Pt-loaded WO3 coating has highest sensitivity when the molar ratio of Pt:W is 1:5. At room temperature of 25 °C, FBG coated with highest sensitivity Pt-loaded WO3 coating has 536 pm wavelength shift toward 10,000 ppm hydrogen, and hydrogen detection threshold of FBG hydrogen sensor can reach to 200 ppm. And ambient humidity has less effect on its performance. FBG hydrogen sensor shows good selectivity (no response to CO and CH4) and repeatability during hydrogen response. The experimental results show FBG hydrogen sensor has continuous hydrogen monitoring ability, and the hydrogen sensor may have great potential for hydrogen's distributed measurement in air.