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Tapered Optical Fiber for Hydrogen Sensing Application Based on Molybdenum trioxide (MoO3)
1, 2 , 3, 4 , 5 , 6 , 4 , * 4
1  Computer Center, University of Fallujah, Al-Fallujah, Iraq.
2  Department of Medical Instrumentations Techniques Engineering , AL-Rasheed University College, Baghdad, Iraq.
3  Department of Computer Engineering, Federal Polytechnic Mubi, Adamawa State, Nigeria.
4  Wireless and Photonics Network Research Center, Faculty of Engineering, University Putra Malaysia,43000 UPM Serdang, Selangor, Malaysia
5  Department of Physics, Faculty of Science, University Putra Malaysia, 43400, Serdang, Selangor, Malaysia
6  Department of Electrical, Electronic and System Engineering, Faculty of Engineering and Built Environment, University Kebangsaan Malaysia, 43600 UKM Bangi, Selangor, Malaysia
Academic Editor: Sabina Merlo


In this work, molybdenum trioxide (MoO3) was synthesized and deposited on tapered optical fiber using the drop-casting technique for hydrogen (H2) detection at room temperature. A transducing platform in a transmission mode was constructed using multimode optical fiber (MMF) with a 125 µm cladding and a 62.5 µm core diameter. To enhance the evanescent light field surrounding the fiber, the fibers were tapered from 125 µm in diameter to 20 µm in diameter with a 10 mm waist. The microstructures and chemical compositions of the fabricated sensor were analyzed by field emission scanning electron microscopy (FESEM), energy dispersive X-ray (EDX), differential X-ray (XRD), and atomic force microscopy (AFM). In addition, the gas detection properties of the fabricated sensor were studied by exposing it to various concentrations of hydrogen gas from 0.125% to 2.00%. As a result, the sensitivity, response, and recovery time were 11.96 vol%, 220 s, and 200 s, respectively. Overall, the fabricated sensor exhibits good sensitivity as well as repeatability and stability for hydrogen gas detection.

Keywords: Hydrogen (H2) gas; tapered optical fiber; evanescent wave; molybdenum trioxide (MoO3) and drop-casting technique.