Sensitive and Repeatable Optical Fiber Hydrogen Sensors Using Plasma-Induced Oxygen Vacancies Magnetron Sputtering Coating Technique

Controlling the formation of oxygen vacancies (OVs) in metal oxide semiconductors (as the gas sensing material) is a significant important, that dominates the sensor's performances for the target of gas (sensitivity, repeatability, response time et al). In this study, we proposed a tilted fiber Bragg grating assisted hydrogen sensor with hybrid palladium and OVs-modified WO<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> metal oxide semiconductors surface functionalization. The innovation of this work is that we propose an Ar plasma-etching technique to regulate OVs concentration in WO<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> by adjusting magnetron sputtering power. The experimental results demonstrate that the signal-to-noise ratio of the proposed H<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> sensor has been much improved, offering a limit of detection as low as 8 ppm together with a strongly enhanced reproducibility for dozens of repeat H<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> measurements. This flexible coating technique offers a mass production way of high-quality specific material functionalization for various kinds of gas sensing.