Tilted Fiber Bragg Grating Sensor Using Chemical Plating of a Palladium Membrane for the Detection of Hydrogen Leakage

Abstract

A tilted fiber Bragg grating (TFBG) hydrogen sensor coated with a palladium (Pd) membrane by the electroless plating method is proposed in this paper. A uniform layer of Pd metal is fabricated in aqueous solutions by the chemical coating method, which is used as the sensitive element to detect the change of the surrounding refractive index (SRI) caused by hydrogen absorption. The change in SRI causes an unsynchronized change of the cladding modes and the Bragg peak in the TFBG transmission spectrum, thereby eliminating the cross-sensitivity due to membrane expansion and is able to simultaneously monitor the presence of cracks in the pipe, as well as the hydrogen leakage. By subtracting the wavelength shift caused by fiber expansion, the change of SRI, i.e., the information from the H2 level, can be separately obtained. The drifted wavelength is measured for the H2 concentration below the hydrogen explosion limit between 1% and 4%. The chemical-based coating has the advantages of a low cost, a simple operation, and being suitable for coating on long fiber structures. The proposed sensor is able to detect the H2 signal in 5 min at a 1% H2 concentration. The proposed sensor is proved to be able to monitor the hydrogen level without the cross-sensitivity of temperature variation and expansion strains, so could be a good candidate for security applications in industry.

Recent Advances in Optical Hydrogen Sensor including Use of Metal and Metal Alloys: A Review

“…In addition of the standard FBG, other grating based fibers were also utilized for the hydrogen sensing with improved sensing response [98]. In the same year 2018, Yu et al demonstrated the titled FBG (TFBG) based hydrogen sensor coated with Pd membrane by the chemical coating method, as shown in Figure 11 [104]. The Pd metal was synthesized in aqueous solutions, which was later utilized to determine variation of the surrounding refractive index corresponding to hydrogen concentrations.…”

Fiber Grating Hydrogen Sensor: Progress, Challenge and Prospect

“…To improve sensor sensitivity, in addition to the method of thinning the fiber cladding thickness, in 2018, J. Yu et al [43] employed tilted fiber Bragg grating (TFBG) to eliminate the cross-sensitivity caused by the external stress. In 2022, C. Zhang et al [44] proposed a TFBG hydrogen sensor based on Pd/Au (25 nm/35 nm) composite nanofilms, as shown in Figure 5a-c.…”

“…The performances of some typical FBG hydrogen sensors based on Pd sensitive materials are summarized in Table 2. [29,31,32,35,36,40,43,[47][48][49][50][51] In addition to the traditional hydrogen-sensitive material preparation method, M. Fisser et al [52] proposed a new process of pasting large area Pd foil on the surface of FBG. As a result of the new process, the response of pure Pd foil is 72% higher than that of the previously reported sensor, [53] with a sensitivity of 0.062 pm ppm −1 .…”

Hydrogen Leakage Diagnosis for Proton Exchange Membrane Fuel Cell Systems: Methods and Suggestions on Its Application in Fuel Cell Vehicles

“…Pt-TiO2/multiwalled carbon nanotubes based sensors are sensitive to hydrogen at volume concentrations between 0.5% and 3% in air, which can meet the requirements for practical applications. Yu et al [22] proposed a tilted fiber Bragg grating hydrogen sensor coated with a palladium membrane by the electroless plating method, it is able to identify the hydrogen in 5 minute at a 1% hydrogen volume concentration. Chauhan et al [23] reviewed different sensing technologies used in existing hydrogen concentration sensors and various materials used in hydrogen sensing.…”