Greatly etched fiber Bragg grating hydrogen sensor with Pd/Ni composite film as sensing material

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.

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Enhanced sensitivity of fiber Bragg grating hydrogen sensor using flexible substrate

Sensors and Actuators B Chemical ◽

10.1016/j.snb.2014.02.069 ◽

2014 ◽

Vol 196 ◽

pp. 604-609 ◽

Cited By ~ 26

Author(s):

Jixiang Dai ◽

Minghong Yang ◽

Zhi Yang ◽

Zhi Li ◽

Yao Wang ◽

...

Keyword(s):

Fiber Bragg Grating ◽

Flexible Substrate ◽

Hydrogen Sensor ◽

Bragg Grating ◽

Enhanced Sensitivity

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Fiber Bragg Grating Hydrogen Sensor Applied for Partial Discharge Detection in Transformer Oil

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.738-739.11 ◽

2015 ◽

Vol 738-739 ◽

pp. 11-14 ◽

Cited By ~ 2

Author(s):

Ying Ting Luo ◽

Hong Bin Wang ◽

Wen Jun Zhu ◽

Zhen Wu ◽

Hong Tu Song ◽

...

Keyword(s):

Light Intensity ◽

Optical Fiber ◽

Fiber Bragg Grating ◽

Hydrogen Generation ◽

Power Transformer ◽

Partial Discharge ◽

Hydrogen Sensor ◽

Gas Analysis ◽

Transformer Oil ◽

Bragg Grating

Most optical hydrogen sensors are based on light intensity measurement and light intensity detection is vulnerable to the light source output and the optical fiber arrangement. To overcome the shortcomings, an optical fiber based sensor based on fiber Bragg grating (FBG) technique which is capable to measure the concentration of hydrogen dissolved is described in this paper. To examine the availability of monitoring initial hydrogen generation, a needle-to-plate partial discharge (PD) model was setup in the lab. The results between wavelength shifts of optical hydrogen sensor well agreed with conventional dissolved gas analysis (DGA), proving a potential utilization in the detection of dissolved hydrogen in power transformer.

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