A New Hydrogen Sensor Based on SNS Fiber Interferometer with Pd/WO₃ Coating.

Jinxin Shao,Wenge Xie,Yanan Zhang,Xi Song

doi:10.3390/s17092144

Abstract

This paper presents a new hydrogen sensor based on a single mode–no core–single mode (SNS) fiber interferometer structure. The surface of the no core fiber (NCF) was coated by Pd/WO3 film to detect the variation of hydrogen concentration. If the hydrogen concentration changes, the refractive index of the Pd/WO3 film as well as the boundary condition for light propagating in the NCF will all be changed, which will then cause a shift into the resonant wavelength of interferometer. Therefore, the hydrogen concentration can be deduced by measuring the shift of the resonant wavelength. Experimental results demonstrated that this proposed sensor had a high detection sensitivity of 1.26857 nm/%, with good linearity and high accuracy (maximum 0.0055% hydrogen volume error). Besides, it also possessed the advantages of simple structure, low cost, good stability, and repeatability.

Highlights

Nowadays, energy has become an increasingly important issue in human development
It is of great value to develop a safe and reliable hydrogen sensor with high sensitivity to monitor the hydrogen concentration in real time
This paper provides a new thought of hydrogen sensor by splicing a no core fiber between two single mode fibers

Summary

Introduction

Energy has become an increasingly important issue in human development. Scientists believe that hydrogen will become another new source of energy to replace petroleum [1,2]. Pellistor-typed catalytic hydrogen sensors are based on the theory that combustion of hydrogen and oxygen on the sensor surface can release heat for measuring. They have a high error rate, high power consumption, and a high risk of explosion [6]. It is obvious that optical fiber hydrogen sensors can realize the measurement of hydrogen concentration with high safety and accuracy. The evanescent field sensor was first proposed by Tabib Azar who coated the sensitive material on the fiber to cause an intensity change in the optical signal [13]. Simulation and experimental results demonstrated that this simple structure can realize a high sensitivity of 1.26857 n m/%, with good linearity, high stability, and good responsiveness

Structure and Principle of Sensor

Simulation Analysis

Experimental Test

Conclusions