Characteristics of an Optical Fiber Hydrogen Gas Sensor Based on a Palladium and Yttrium Alloy Thin Film

To improve the hydrogen sensor characteristics, the choice of doping atoms in Pd is crucial. A novel palladium (Pd) and yttrium (Y) thin film is prepared and utilized to design a reflected optical fiber hydrogen gas sensor. The performance and mechanical properties of the hydrogen sensor are examined. Experimental results show that the response value of the sensor decreases evidently and rapidly with increasing hydrogen concentration, the first drift of zero point of sensors increases as hydrogen concentration increases, and frequent use can reduce the drift of the sensor and increase repeatability. The sensor with Pd-Y alloy film possesses smaller zero point drift and better resistance to hydrogen embrittlement than that with pure Pd film after several hydrogen loading/unloading cycles. Several thin film samples with different thicknesses are fabricated and tested. The sensitivity of the sensor is higher at low-concentration hydrogen and thick film.