Fiber optic hydrogen sensors: a review

Abstract

Hydrogen is one of the next generation energies in the future, which shows promising applications in aerospace and chemical industries. Hydrogen leakage monitoring is very dangerous and important because of its low ignition energy, high combustion efficiency, and smallest molecule. This paper reviews the state-of-art development of the fiber optic hydrogen sensing technology. The main developing trends of fiber optic hydrogen sensors are based on two kinds of hydrogen sensitive materials, i.e. palladium-alloy thin films and Pt-doped WO 3 coatings. In this review work, the advantages and disadvantages of these two kinds of sensing technologies will be evaluated.

Optical sensor for hydrogen gas based on a palladium-coated polymer microresonator

“…It is well known for Pd expansion based hydrogen sensors that the ambient conditions (humidity and oxygen) deteriorate the sensor parameters such as sensitivity and response time. Such drawbacks that were previously reported for Pd coated micro/nano cantilever based hydrogen sensors [33,34] and Pd coated fiber Bragg grating sensors [35,36] should also be expected for the operation of the sensor device we demonstrate in this paper.…”

Fiber-optic Fabry-Perot hydrogen sensor coated with Pd-Y film

“…The Pd-Y film has the good recovery property and can be used for multiple times for hydrogen sensing. In this aspect, the performance of the Pd film is not as good as the Pd-Y film [11]. …”

“…The Pd-Y film absorbs hydrogen, and PdH-Y is produced, leading to the changes in both optical loss and the refractive index of the film. Pd-Y was proved to be an ideal sensitive material for a hydrogen sensor [11]. The optical fiber sensor measures refractive index changes based on the interaction between the hydrogen and Pd-Y film, which induces the change in the refractive index of the Pd-Y film which is coated on the optical GI-MMF fiber end.…”

“…The further Pd-Y film was used for hydrogen sensing [11]. In this paper, a novel hydrogen sensor is proposed and demonstrated based on the graded-index multimode fiber (GI-MMF) Fabry-Perot (FP) structure [12] coated with a Pd-Y film.…”

Hydrogen gas sensors based on electrostatically spray deposited nickel oxide thin film structures

“…The precursor solution comprises an organic solvent in which an inorganic salt is dissolved. For a particularly applied voltage difference and liquid flow rate, certain spaying modes are obtained of which the cone-jet mode (Taylor cone-jet mode) is the most encountered one [7,8]. The highly charged aerosol droplets made by the applied high electric field shrink by solvent evaporation.…”