A Robust Fiber Bragg Grating Hydrogen Gas Sensor Using Platinum-Supported Silica Catalyst Film

Abstract

A robust fiber Bragg grating (FBG) hydrogen gas sensor for reliable multipoint-leakage monitoring has been developed. The sensing mechanism is based on shifts of center wavelength of the reflection spectra due to temperature change caused by catalytic combustion heat. The sensitive film which consists of platinum-supported silica (Pt/SiO 2 ) catalyst film was obtained using sol-gel method. The precursor solution was composed of hexachloroplatinic acid and commercially available silica precursor solution. The atom ratio of Si : Pt was fixed at 13 : 1. A small amount of this solution was dropped on the substrate and dried at room temperature. After that, the film was calcined at 500°C in air. These procedures were repeated and therefore thick hydrogen-sensitive films were obtained. The catalytic film obtained by 20-time coating on quartz glass substrate showed a temperature change 75 K upon exposure to 3 vol.% H 2 . For realizing robust sensor device, this catalytic film was deposited and FBG portion was directly fixed on titanium substrate. The sensor device showed good performances enough to detect hydrogen gas in the concentration range below lower explosion limit at room temperature. The enhancement of the sensitivity was attributed to not only catalytic combustion heat but also related thermal strain.

Performance Optimization of Apodized FBG Biomedical Sensor for Variation in Temperature and Presence of Noise

“…where λ B is the shifted Bragg wavelength, ε the applied strain, P e is the effective photo elastic coefficient and λ B the Bragg grating center wavelength. And the effect of variation in temperature on dual mode FBG sensor is represented by complex model given in (11).…”

“…Later, many extensions to these basic formulations were made, for example, [10] used two tunable uniform FBGs to measure gas concentration by using intracavity absorption spectroscopy technique. Moreover, Kurohiji et al [11] used single FBG element to design hydrogen gas sensor for leakage detection in pipelines. As FBG has many types the most widely used type of FBG is uniform FBG.…”

Hollow-Core Photonic Crystal Fiber Gas Sensing

“…The properties of light, such as intensity, polarization, phase, and nonlinearity may change after the light-gas interaction around or inside the fiber, so gas species and concentrations can be obtained by detecting the variations of these parameters in fiber-based gas sensors. Nowadays, except for the widely used fiber grating gas sensors, such as fiber Bragg grating [25][26][27][28] and long period grating gas sensors [29][30][31][32][33], other fiber-based gas sensors rely on the direct absorption of molecules [34,35], Raman scattering [36][37][38], photothermal effect [17,39], photoacoustic effect [40][41][42], fluorescence [43], and surface plasmon resonance [44] have also been proposed and developed.…”

Doping Transition Metals into TiO2‐CNT Nanocatalyst to Enhance the Selective Oxidation of H2S

“…In contrast, transition metal cations have been used as dopants and co-catalysts [31][32][33] in improvement reactions. [34,35] Iron (Fe 3 + ) doped magnesium oxide, [36] Fe-containing SBA-15 silica, [37] binary oxides such as VÀ Mg, VÀ Bi, VÀ Mo, VÀ Sb, and FeÀ Sn, BiÀ Mo [38] and Iron-molybdenum-oxide [39] catalysts have been investigated for selective oxidation H 2 S. Recently, we introduced the synthesis of TiO 2 -CNT hybrid nanocatalyst by using the sol-gel method and determined its activity in selective oxidation of H 2 S. [40] TiO 2 activity can be increased by surface defects through introduction of heteroatoms in TiO 2 lattice or the removing the lattice oxygen and engineering the oxygen deficiency. [41] Also, CNTs are also used for selective oxidation of H 2 S, however, CNT by itself is not active enough in this reaction.…”