Optical Fiber Hydrogen Sensor Research Articles

Pd–Ta alloy films hydrogen sensors based on partially coated π -phase-shifted FBG

A fiber-optic hydrogen sensor based on Pd–Ta alloy films partially coated π-phase-shifted fiber-Bragg grating (FBG) is proposed and experimentally demonstrated. Three types of Pd–Ta alloy films with different Ta content were prepared via co-sputtering technology. Material characterization shows the transformation of Pd–Ta alloy to amorphous phase with the increase of Ta content, and the phase transition between α-PdTaHx and β-PdTaHx is inhibited at 2 % hydrogen concentration. Hydrogen sensing experiments show that in-situ temperature compensation is possible with Pd/Ta films partially coated on π-phase-shifted FBG. Moreover, the sensor's hysteresis phenomenon was eliminated with an increase in Ta content due to the first-order phase transition. Pd–Ta alloy films hydrogen sensor with a Ta content of 27 % is capable of in-situ temperature compensation, fast response, good stability, and reliability.

Spectroscopic Techniques and Hydrogen-Sensitive Compounds: A New Horizon in Hydrogen Detection.

Detecting hydrogen leaks remains a pivotal challenge demanding robust solutions. Among diverse detection techniques, the fiber-optic method distinguishes itself through unique benefits, such as its distributed measurement properties. The adoption of hydrogen-sensitive materials coated on fibers has gained significant traction in research circles, credited to its operational simplicity and exceptional adaptability across varied conditions. This manuscript offers an exhaustive investigation into hydrogen-sensitive materials and their incorporation into fiber-optic hydrogen sensors. The research profoundly analyzes the sensor architectures, performance indicators, and the spectrum of sensing materials. A detailed understanding of these sensors' potentials and constraints emerges through rigorous examination, juxtaposition, and holistic discourse. Furthermore, this analysis judiciously assesses the inherent challenges tied to these systems, simultaneously highlighting potential pathways for future innovation. By spotlighting the hurdles and opportunities, this paper furnishes a view on hydrogen sensing technology, particularly related to optical fiber-based applications.

Quasi-distributed optical fiber hydrogen leakage detecting system based on bus chain topology structure

Micro-mirror optical fiber hydrogen sensors have the advantages of compact structure and fast demodulation speed. All-optical sensor networks consisting of micro-mirror optical fiber hydrogen sensors are essentially necessary across the hydrogen value chain. A bus chain topology structure hydrogen leakage detecting system based on micro-mirror sensors is proposed and experimentally demonstrated. A compensating optical path with constant power supply is introduced, and the power dissipation scheme is theoretically and experimentally proposed by designating the splitting ratios of the splitters array. By constructing such a network with twenty micro-mirror hydrogen sensors, the system has been experimentally verified with good repeatability and stability under different concentrations of hydrogen. By employing this bus chain topology strategy, a quasi-distributed optical fiber hydrogen leakage detection system with micro-mirror hydrogen sensors array is realized. It will provide a promising solution with high feasibility on multi-point leakage detecting in hydrogen infrastructures.

Highly sensitive fiber grating hydrogen sensor based on hydrogen-doped Pt/WO3

Hydrogen sensors are key to the emerging clean hydrogen economies and fiber-optic hydrogen sensors play a unique role owing to their inherent safety and high sensitivity. Currently Pt/WO3 has been employed as the mainstream hydrogen-sensitive material in high performance hydrogen sensors. Here we develop an ultrasensitive fiber-optic hydrogen sensor with fast response by coating pretreated Pt/WO3 nanomaterial on fiber Bragg grating. We observe a great enhancement in sensitivity by the hydrogen-doping of the Pt/WO3 nanomaterials. The generation of HxWO3 composite material is confirmed by XRD, FTIR and Raman analysis. Compared with pure Pt/WO3, a 184-fold improvement in sensitivity is achieved by hydrogen doping, with a fast response of 25 s. An impressive limit of detection (LOD) of 30 ppm is demonstrated by employing both the narrowband weak FBGs and the hydrogen-doped Pt/WO3. The immunity to ambient temperature fluctuation is demonstrated by self-calibration through detecting the wavelength difference between a pair of FBGs. Good specificity is also demonstrated. This technology shows great potential in high spatial-resolution quasi-distributed hydrogen sensing.

Improved performance of fiber-optic hydrogen sensor of porous Pt/WO3 based on ZIF-8

A novel fiber-optic hydrogen sensor including Pt/WO3 sensing material with a microporous structure is proposed and experimentally demonstrated with improved performance. The proposed Pt/WO3 sensing material is realized by introducing metal-organic frameworks (MOFs) as templates. The mesoporous structure of the ZIF-8 template improves the reactive sites of hydrogen sensitive materials with hydrogen. Hydrogen sensors were fabricated by combining the synthesized material with Fiber Bragg Gratings (FBGs) and the performance of hydrogen sensors was investigated. The experimental results show that the hydrogen sensitivity of the FBG with ZIF-8 synthesized Pt/WO3 has been increased to 0.075 pm/ppm, which is twice that without ZIF-8 synthetization. The stability and the response speed are also significantly improved. The introduction of microporous MOFs templates into Pt/WO3 sensing material will greatly accelerate the wide application of Pt/WO3-based fiber optic hydrogen sensors on hydrogen leakage detection.

A Review of Hydrogen Sensors for ECLSS: Fundamentals, Recent Advances, and Challenges

The development of hydrogen sensors with high detection accuracy, fast response times, long calibration periods, and good stability has become the focus of the space station environmental control and life support subsystem. We analyze the current research status of different types of hydrogen sensors, including catalyst combustion type, heat conduction type, semiconductor type, fiber optic type, etc. The response signals of most hydrogen sensors are affected by temperature and humidity, resulting in cross-sensitivity. Reducing the cross-sensitivity of temperature, humidity, and other interfering factors to achieve accurate hydrogen measurement in different environments is a challenge that limits the development of hydrogen sensors. Several hydrogen sensors that are currently commercially available have a narrow operating temperature range, most of them can only measure at room temperature, and high-temperature environments require a higher accuracy and lifetime of the sensor than required at room temperature. Many new hydrogen-sensitive materials were developed to improve the performance of the sensors. The excellent performance of fiber-optic hydrogen sensors is beneficial to temperature compensation and distributed multiparameter measurement, as well as to the research and development of intelligent sensing systems, in the context of the Internet of Things. The signal detection and demodulation techniques of fiber-optic sensors are the focus of future hydrogen sensor research.

Fiber-tip Fabry-Pérot interferometer with a graphene-Au-Pd cantilever for trace hydrogen sensing.

The widespread utilization of hydrogen energy has increased the demand for trace hydrogen detection. In this work, we propose a fiber-optic hydrogen sensor based on a Fabry-Pérot Interferometer (FPI) consisting of a fiber-tip graphene-Au-Pd submicron film cantilever. The palladium (Pd) film on the cantilever surface is used as hydrogen-sensitive material to obtain high sensing sensitivity. Hydrogen sensing is realized by monitoring the resonant frequency shift of the FPI introduced by the interaction between Pd film and hydrogen molecules. The hydrogen sensor is proven for low-hydrogen-concentration detection with hydrogen concentrations in the range of 0-1000 ppm, and experimentally characterized by a highest sensitivity of 30.3 pm ppm-1 in a low hydrogen concentration of 0-100 ppm, which is more than two orders higher than for previously reported FPI-based sensors. In real-time hydrogen monitoring, a rapid reaction time of 31.5 s was achieved. This work provides a compact all-optical solution for the safe detection of low hydrogen concentrations, which is an interesting alternative for trace hydrogen detection in the aerospace industry, energy production, and medical applications.

Performance of Fiber-Optic Hydrogen Sensor Based on Locally Coated π-Shifted FBG

Pd-based alloy coating on optical fiber is widely employed for hydrogen concentration sensing. However, it is difficult to distinguish the Pd-based alloy expansion from hydrogen adsorption or thermal effect. In this article, a novel fiber-optic hydrogen sensor based on <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\pi $ </tex-math></inline-formula> -shifted fiber Bragg grating (FBG) with locally coated Pd/Ta alloy layer, which enables an in situ temperature compensation, is proposed and experimentally demonstrated. The hydrogen sensitivity difference between the extremely narrow peak of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\pi $ </tex-math></inline-formula> -shifted FBG and the sidelobe wavelength is employed to realize the hydrogen concentration detection with temperature compensation. Theoretical simulation and experiment show that the hydrogen sensitivity of the structure can be enhanced by optimizing the partially coating length. When the alloy length is 2 mm for a 10-mm grating, the wavelength shifts of central and sidelobe 19.2 pm and 6.0 pm are achieved, respectively, at 1% hydrogen concentration. Maximum hydrogen sensitivity after temperature compensation of 13.2 pm is obtained. The proposed local-compensated method based on partially coating on <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\pi $ </tex-math></inline-formula> -shifted FBG is particularly potential for oxygen-free environments with high requirement on hydrogen accuracy.

Lateral Offset Single-Mode Fiber-Based Fabry-Perot Interferometers with Vernier Effect for Hydrogen Sensing.

A high-sensitive optical fiber hydrogen (H2) sensor with Vernier effect by cascading three Fabry-Perot interferometers (FPIs) has been proposed. It is prepared by welding three sections of a single-mode fiber with a lateral offset structure and coating polydimethylsiloxane (PDMS) at the offset part to form three cascaded FPIs and generate a Vernier envelope spectrum. To realize H2 sensing, the hydrogen-sensitive material Pd/WO3 is fabricated and coated on the outside of the PDMS. Pd/WO3 will generate local heat when in contact with H2, which will cause the thermal expansion and refractive index change of PDMS and finally lead to the Vernier envelope wavelength shifting with the change of H2 concentration. Due to the Vernier effect, the H2 sensor can achieve a linear measurement sensitivity of 6.214 nm/% in the concentration range of 0-1%, which is 16.11 times that of a single FPI. The proposed H2 sensor possesses advantages of high sensitivity, easy preparation, compact structure, low cost, and easy long-distance transmission.

Optical fiber hydrogen sensor based on self-assembled PDMS/Pd-WO3 microbottle resonator

In this paper, a new optical fiber hydrogen(H2) sensor based on a self-assembled microbottle resonator was proposed. The self-assembled microbottle was simply obtained by coating the single-mode fiber (SMF) with an internal composite material layer of palladium-tungsten trioxide (Pd-WO3) that was sensitive to H2 and an outer organic polymer material layer of polydimethylsiloxane (PDMS) with a significant thermal response. The microbottle resonator was further fabricated by coupling a tapered fiber with the self-assembled microbottle to excite whispering gallery mode (WGM). When the WGM resonator is exposed to H2, H2 molecules penetrate the PDMS and undergo redox reaction with the Pd-WO3. After the PDMS absorbs the reaction heat, its volume and refractive index will change, along with the wavelength shift of the WGM resonator. Therefore, a simple and low-cost H2 sensor is realized by observing the shift of resonance wavelength. Experimental results showed that the hydrogen sensor had a maximum sensitivity of − 3.091 nm/% at 25 ℃. And the resonance wavelength just shifted a small distance when the relative humidity increased from 22.87 % to 84.59 % or the temperature rose from 20.2 ℃ to 30 ℃, which indicated the sensor had preferable resistance to disturbances of external humidity and temperature.

Reflective-Type High Sensitivity Optical Fiber Hydrogen Sensor Based On Enlarged Taper Cascaded With Tilted Fiber Grating

Highly sensitive reflective-type fiber hydrogen sensor based on an enlarged taper cascaded with a tilted fiber grating (TFBG) was proposed. Hydrogen-sensitive Au-Pd nanofilm was coated on the TFBG surface by magnetron sputtering means. By cascading an enlarged taper upstream to the TFBG, cladding modes and Ghost mode of the TFBG could be coupled into the core to form a reflective-type TFBG-based hydrogen sensor. As the hydrogen was absorbed by the Au-Pd nanofilm, the effective refractive index of the cladding of the TFBG will change accordingly, so as to the reflective spectra of the TFBG. The hydrogen concentration was obtained through the intensity changing of the ghost mode in the reflective spectra of TFBG. The proposed sensor showed a high sensitivity of 4.83 dB/% with a calculated LOD of 0.07% for the hydrogen concentration range from 0% to 0.7% at room temperature with the rapid response time of 26 s and recovery time of 40 s, respectively.

Optics-mechanics synergistic fiber optic sensor for hydrogen detection.

As a carbon-free energy carrier and an attractive alternative energy source, hydrogen energy has great development potential for future considerations, and it may be the ultimate answer to the global energy crisis. Due to the high combustibility of hydrogen, hydrogen sensors will be a vital component of safe use of hydrogen. Among the various sensors, the optical hydrogen sensor can meet the requirements of intrinsic safety, online detection, surrounding immunity, and lack of spark. Hence, we demonstrate a miniature optics-mechanics synergistic fiber optic hydrogen sensor by using Pd nanofilm, it has a large response range (0.5%-3.5%), high sensitivity of -0.334 nm/1% concentration and a short response time (10s)/recovery time (25s). Experimental results reveal that the proposed optics-mechanics synergistic fiber optic hydrogen sensor is reusable, durable, and low temperature sensitive. In this optics-mechanics synergistic fiber optic hydrogen sensor, nano Pd film with a large surface-to-volume ratio allows for rapid hydrogen dissociation, and Pd lattice expansion caused by Pd-hydrogen reaction is effectively transduced into optical change. This proposed sensor integrated Pd nanofilm with optical fiber by using an optics-mechanics synergistic strategy, resulting in a compact and all-optical solution for the safe measurement of hydrogen concentration, which can be used in hazardous or space-limited environments.

Hotspot and frontier discovery of hydrogen detection technology based on bibliometrics

PurposeWith the acceleration of global energy structure transformation, hydrogen has been widely used for its non-pollution and high efficiency, and hydrogen detection is used to guarantee the hydrogen safety. The purpose of this paper is to study the research foundation, trend and hotspots of hydrogen detection field.Design/methodology/approachA total of 4,076 literature records from 2000 to 2021 were retrieved from the core collection of the Web of Science database selected as data sources. The literature information mining was realized by using CiteSpace software. Bibliometrics was used to analyze information, such as keywords, authors, journals, institutions, countries and cited references, and to track research hotspots.FindingsSince the 21st century, the number of publications in the hydrogen detection field has been in a stable stepped uptrend. In terms of research foundation, the hotspots such as core-shell structures, nano-hybrid materials and optical fiber hydrogen sensors have been studied extensively. In combination with the discipline structure and research frontier, the selectivity, sensitivity, response speed and other performance parameters of hydrogen sensors need further improvement. The establishment of an interdisciplinary knowledge system centered on materials science and electronic science will become a long-term trend in the research of hydrogen detection.Originality/valueThis study presents an overview of research status, hotspots and laws in hydrogen detection field, through the quantitative analysis of much literature in the field and the use of data mining, so as to provide credible references for the research of hydrogen detection technology.

TBAOH intercalated WO3 for high-performance optical fiber hydrogen sensor

Considering the poor response performance of fiber bragg grating (FBG) sensor based on WO3, in this paper, a polymer intercalated method is proposed to accomplish high-performance optical fiber hydrogen sensor. Tetrabutylammonium hydroxide (TBAOH) molecule intercalated WO3 are synthesized successfully and the effect of the intercalation amount to sensing performance has been investigated. The experiment results show that, at the concentration of 10,000 ppm, the t90 response time of the sensor based on TBAOH-Pt/WO3 is improved by 308% compared with that of WO3 FBG sensor. In addition, the FBG hydrogen sensor based on the novel materials can detect hydrogen concentration ranging from 300 ppm to 12,000 ppm in air, demonstrating excellent stability and repeatability, which show wide application prospect in the future.

Progress and prospects of research on hydrogen sensors

<p indent="0mm">The development of hydrogen energy industry is of great significance to the construction of a clean, low-carbon, safe and efficient modern energy system, the realization of the “dual carbon” goal and the high-quality economic development. The safe use of hydrogen has always been a concern. Hydrogen sensors can quickly and accurately measure hydrogen concentration, and effectively prevent hydrogen leakage, explosion and other safety problems in the process of production, storage, transportation and use. In recent years, with the popularization and application of hydrogen energy and the rapid development of Internet of Things technology, the requirements for hydrogen sensors in security, remote monitoring and distributed measurement are increasing. In this paper, the principle, applicability and research status of different types of hydrogen sensors are reviewed and analyzed, and the development trend of hydrogen sensors is forecasted. Hydrogen sensors can be divided into catalytic, electrical, optical fiber, acoustic and other types according to sensing principles. The catalytic hydrogen sensor has simple structures, fast response and high sensitivity. However, the catalytic hydrogen sensor is greatly affected by the temperature and humidity, and it has poor gas selectivity and high working temperature, which leads to potential safety hazards. The electrical hydrogen sensor has simple structures, long service life, and is easy to be integrated and miniaturized. However, electrical signals are prone to environmental interference and lead to signal drift, and electrical sparks may be generated during the detection of electrical signals, which can cause explosions in the detection of combustible gas. Compared with traditional electrical sensors, fiber optic hydrogen sensors have higher security and anti-interference, and are convenient to realize distributed measurement and other excellent performance, which has become a research hotspot. The fiber optic hydrogen sensor is small in size, intrinsically safe, anti-electromagnetic interference, and it can realize distributed spatial multi-point measurement. However, it is difficult to achieve commercial production due to its high cost, complex signal processing and expensive instruments for detection. The acoustic hydrogen sensor has high sensitivity and fast response time, but is greatly affected by temperature and humidity. The future challenges and opportunities for hydrogen sensors are also discussed in the last section. Under the background of Internet of Things and the era of big data, the research of hydrogen sensors will be gradually toward miniaturization, integration and distributed sensing. Moreover, it is necessary to realize hydrogen detection at high temperature and humidity. Future research in this field may focus on the following four aspects: (1) Reducing the cross sensitivity of temperature, humidity and other gases; (2) new hydrogen-sensitive materials such as nanomaterials and graphene; (3) performance optimization of hydrogen sensors at high temperature; (4) signal detection and demodulation device of fiber optic sensors.

Optical Fiber Hydrogen Sensor Based on the EVA/Pd Coated Hollow Fiber

A novel optical fiber hydrogen sensor based on the dielectric/metal coated hollow fiber structure is proposed. The palladium (Pd) and ethylene-vinyl acetate (EVA) layers are sequentially coated on the inner surface of the hollow core of the silica capillary to fabricate the EVA/Pd coated hollow fiber sensor. Theoretical ray transmission model is carried out to analyze the influence of the thicknesses of the Pd and EVA films. The experimental transmission spectra of the proposed sensor filled with hydrogen gas of different concentrations are measured. The experimental results show that the interference peak in the spectrum has a red shift with the increase of hydrogen concentration. Then the hydrogen concentration can be obtained by measuring the wavelength of the interference peak. In the range of 0–4% hydrogen concentration, the total shift is 10.64nm and the average sensitivity is 2.66 nm/%. Compared to other optical fiber hydrogen sensors, the proposed sensor has the advantages of simple structure, easy fabrication, low cost, high sensitivity and good safety performance.

Fiber optic localized surface plasmon resonance hydrogen sensor based on gold nanoparticles capped with palladium

We propose an optical fiber-based localized surface plasmon resonance sensor to overcome limitations with hydrogen gas explosions in various types of hydrogen sensors and minimize human damage caused by exposure to hazardous environments. For selective detection of hydrogen, a simple palladium-capping process was applied on a fiber-optic localized surface plasmon resonance. After the palladium-capping, the sensor was exposed to various refractive index solutions to confirm the linearity of the response. Hydrogen gas reactivity was measured at concentrations from 0.8% to 4%; the reaction time at each concentration was observed as 116 s until the signal stabilized. The coefficient of variation (CV) and limit of detection (LOD) were calculated based on the results obtained through repeated measurements. The reproducibility was verified with an average CV of 11%. In addition, the developed sensor showed a low LOD of 0.086%. The hysteresis characteristic was observed within 1% in the output change, which was similar to the fluctuation range allowed by the light source per time. The proposed sensor based on the optical principle is expected to reduce the risk of explosions and has advantages in a simple configuration and low-cost production based on optical fiber.

Photothermal-assisted hydrogen permeation enhancement

Herein, we propose and demonstrate a novel all-optical photothermal-assisted hydrogen permeation enhancement scheme by using a special optics-mechanics synergistic fiber optic hydrogen sensor. This design is mainly based on the interdependencies between Pd-hydrogen reaction temperature and hydrogen permeation; as to observe the influence that the photothermal effect has on the hydrogen permeation, this influence is converted to the time-dependent response of the Pd-based hydrogen sensor. Thus, we designed a special optics-mechanics synergistic fiber optic hydrogen sensor, which is convenient for investigating the influence of the photothermal effect and looking at hydrogen permeation, for static and dynamic hydrogen detection. The configuration of this optics-mechanics synergistic fiber optic hydrogen sensor, viewed from the perspective of the form, consists of a fiber Fabry-Perot (FP) cavity and a hydrogen-sensitive Pd nano-film; the Pd film bestows it hydrogen detection capability and undertakes the influence of photothermal effect. The experimental results reveal that this optics-mechanics synergistic fiber optic hydrogen sensor can be used for high efficiency hydrogen sensing and the validation of temperature-dependent hydrogen permeation, and all-optical photothermal assistance can be regarded as a new effective method to enhance absorption/dehydrogenation rate, which is beneficial for achieving rapid and real-time hydrogen detection.

Optical fiber hydrogen sensor using metasurfaces composed of palladium

Palladium-based hydrogen sensors have been typically studied due to the dielectric function that changes with the hydrogen concentration. However, the development of a reliable, integral, and widely applicable hydrogen sensor requires a simple readout mechanism and an optimization of the fast detection of hydrogen. In this work, optical fiber hydrogen sensing platforms are developed using an optimized metasurface, which consists of a layer of palladium nanoantennas array suspended above a gold mirror layer. Since the optical properties of these palladium nanoantennas differ from the traditional palladium films, a high reflectance difference can be achieved when the sensor based on the metasurface is exposed to the hydrogen atmosphere. Finally, the optimized reflectance difference ΔR of ∼0.28 can be obtained when the sensor is exposed in the presence of hydrogen. It is demonstrated that this integrated system architecture with an optimized palladium-based metasurface and a simple optical fiber readout system provides a compact and light platform for hydrogen detection in various working environments.

High-sensitivity optical fiber hydrogen sensor based on the metal organic frameworks of UiO-66-NH2.

A hydrogen sensor with high sensitivity was demonstrated by coating the metal organic frameworks of ${\rm{UiO}}\! -\! {\rm{66 \!-\! N}}{{\rm{H}}_2}$ on an optical fiber Mach-Zehnder interferometer (MZI). The MZI was made of a fiber mismatch structure by using a core-offset fusion splicing method. The effective refractive index of the ${\rm{UiO}}\! -\! {\rm{66\! -\! N}}{{\rm{H}}_2}$ film varied with the absorption and release of hydrogen, and the interference resonant dip wavelength and the intensity of the MZI changed with the variations of the concentration of hydrogen. The experimental results showed that the proposed sensor had a high hydrogen sensitivity of 8.78 dB/% in the range from 0% to 0.8%, which is almost seven times higher than the existing similar hydrogen sensor.