Hydrogen sensor

File:Greg Glatzmaier determines the high-temperature thermal and mechanical stability of sealants used in a lab prototype of the integrated hydrogen sensor separator module.jpg, determines the high-temperature thermal and mechanical stability of sealants used in a lab prototype of the integrated hydrogen sensor separator module.]]

A hydrogen sensor is a gas detector that detects the presence of hydrogen. They contain micro-fabricated point-contact hydrogen sensors and are used to locate hydrogen leaks. They are considered low-cost, compact, durable, and easy to maintain as compared to conventional gas detecting instruments.{{cite web|url=http://ir.lib.sfu.ca/retrieve/2097/etd1726.pdf|title=MOS Capacitor Sensor Array for Hydrogen Gas Measurement|last=Qu|first=Xi Dong|year=2005|publisher=Simon Fraser University|access-date=2008-10-21|archive-url=https://web.archive.org/web/20110706203529/http://ir.lib.sfu.ca/retrieve/2097/etd1726.pdf|archive-date=2011-07-06|url-status=dead}}

Key issues

There are five key issues with hydrogen detectors:{{cite web|url=http://www1.eere.energy.gov/hydrogenandfuelcells/pdfs/30535bb.pdf|title=Interfacial Stability Of Thin Film Hydrogen Sensors |last=Pitts|first=Ronald |author2=Ping Liu |author3=Se-Hee Lee |author4=Ed Tracy|publisher=National Renewable Energy Laboratory|access-date=2008-10-21}}

Reliability: Functionality should be easily verifiable.
Performance: Detection 0.5% hydrogen in air or better
Response time < 1 second.
Lifetime: At least the time between scheduled maintenance.
Cost: Goal is $5 per sensor and $30 per controller.

=Additional requirements=

Measurement range coverage of 0.1–10.0% concentration[http://www.nrel.gov/hydrogen/pdfs/42987.pdf NREL-Hydrogen Sensor Testing oct 2008] {{webarchive|url=https://web.archive.org/web/20090506194332/http://www.nrel.gov/hydrogen/pdfs/42987.pdf |date=2009-05-06 }}
Operation in temperatures of −30 °C to 80 °C
Accuracy within 5% of full scale
Function in an ambient air gas environment within a 10–98% relative humidity range
Resistance to hydrocarbon and other interference.
Lifetime greater than 10 years

Types of microsensors

There are various types of hydrogen microsensors, which use different mechanisms to detect the gas.{{Cite journal |last1=Swager |first1=Timothy M. |last2=Pioch |first2=Thomas N. |last3=Feng |first3=Haosheng |last4=Bergman |first4=Harrison M. |last5=Luo |first5=Shao-Xiong Lennon |last6=Valenza |first6=John J. |date=2024-05-24 |title=Critical Sensing Modalities for Hydrogen: Technical Needs and Status of the Field to Support a Changing Energy Landscape |url=https://pubs.acs.org/doi/10.1021/acssensors.4c00251 |journal=ACS Sensors |language=en |volume=9 |issue=5 |pages=2205–2227 |doi=10.1021/acssensors.4c00251 |pmid=38738834 |issn=2379-3694|url-access=subscription }} Palladium is used in many of these, because it selectively absorbs hydrogen gas and forms the compound palladium hydride.{{cite web|url=http://www.innovations-report.com/html/reports/physics_astronomy/report-44815.html|title=Hydrogen sensors are faster, more sensitive|date=2005-05-31|publisher=Innovations Report|access-date=2008-10-21}} Palladium-based sensors have a strong temperature dependence which makes their response time too large at very low temperatures.{{cite conference|last=Guemes|first=J. Alfredo|author2=Pintado, J. M. |author3=Frovel, M. |author4=Olmo, E. |author5= Obst, A. |date=May 2005|title=Comparison of three types of fibre optic hydrogen sensors within the frame of CryoFOS project|conference=17th International Conference on Optical Fibre Sensors|volume=5855|bibcode=2005SPIE.5855.1000G|doi=10.1117/12.623731|pages=1000|s2cid=108642357}} Palladium sensors have to be protected against carbon monoxide, sulfur dioxide and hydrogen sulfide.

=Optical fibre hydrogen sensors=

Several types of optical fibre surface plasmon resonance (SPR) sensor are used for the point-contact detection of hydrogen:

Fiber Bragg grating coated with a palladium layer – Detects the hydrogen by metal hindrance.
Micromirror – With a palladium thin layer at the cleaved end, detecting changes in the backreflected light.
Tapered fibre coated with palladium – Hydrogen changes the refractive index of the palladium, and consequently the amount of losses in the evanescent wave.

=Other types=

Electrochemical hydrogen sensor – low (ppm) levels of hydrogen gas can be sensed using electrochemical sensors which comprise an array of electrodes packaged so as to be surrounded by a conductive electrolyte and gas ingress controlled with a diffusion limited capillary.
MEMS hydrogen sensor – The combination of nanotechnology and microelectromechanical systems (MEMS) technology allows the production of a hydrogen microsensor that functions properly at room temperature. One type of MEMS-based hydrogen sensor is coated with a film consisting of nanostructured indium oxide ({{chem2|In2O3}}) and tin oxide ({{chem2|SnO2}}).{{cite web|url=http://nsfreunano.research.ucf.edu/YearBook/Titans/2004/alvero.html|title=A Nanoparticle-based Hydrogen Microsensor|last=Alverio|first=Gustavo|publisher=University of Central Florida|access-date=2008-10-21|url-status=dead|archive-url=https://web.archive.org/web/20081204162842/http://nsfreunano.research.ucf.edu/YearBook/Titans/2004/alvero.html|archive-date=2008-12-04}} A typical configuration for mechanical Pd-based hydrogen sensors is the usage of a free-standing cantilever that is coated with Pd.{{cite journal|title=Design and performance of a microcantilever-based hydrogen sensor|journal=Sensors and Actuators B: Chemical|volume=88|issue=2|pages=120–131|last=Baselt|first=D.R.|doi=10.1016/S0925-4005(02)00315-5|year=2003|bibcode=2003SeAcB..88..120B }}{{cite journal |last1=Okuyama |first1=S.O.S. |last2=Mitobe |first2=Y.M.Y. |last3=Okuyama |first3=K.O.K. |last4=Matsushita |first4=K.M.K. |title=Hydrogen gas sensing using a Pd-coated cantilever |journal=Japanese Journal of Applied Physics |volume=39 |issue=6R |pages=3584 |date=2000 |doi=10.1143/JJAP.39.3584 |bibcode=2000JaJAP..39.3584O |url=https://iopscience.iop.org/article/10.1143/JJAP.39.3584/meta|url-access=subscription }} In the presence of {{chem2|H2}}, the Pd layer expands and thereby induces a stress that causes the cantilever to bend. Pd-coated nanomechanical resonators have also been reported in literature, relying on the stress-induced mechanical resonance frequency shift caused by the presence of {{chem2|H2}} gas. In this case, the response speed was enhanced through the use of a very thin layer of Pd (20 nm). Moderate heating was presented as a solution to the response impairment observed in humid conditions.{{cite journal|url=http://pubs.rsc.org/en/Content/ArticleLanding/2012/NR/c2nr30639e|title=Ultra-low power hydrogen sensing based on a palladium-coated nanomechanical beam resonator|last=Henriksson|first=Jonas|journal=Nanoscale|year=2012|volume=4|issue=16|pages=5059–64|publisher=Nanoscale Journal|doi=10.1039/c2nr30639e|pmid=22767251|bibcode=2012Nanos...4.5059H|access-date=2013-02-26}}
Thin film sensor – A palladium thin film sensor is based on an opposing property that depends on the nanoscale structures within the thin film. In the thin film, nanosized palladium particles swell when the hydride is formed, and in the process of expanding, some of them form new electrical connections with their neighbors. The resistance decreases because of the increased number of conducting pathways.{{cite web|url=http://www.makelengineering.com/dir/Technologies/Hydrogen%20Detection/Hydrogen.htm|title=Hydrogen Detection Systems|publisher=Makel Engineering|access-date=2008-10-21}}
Thick film sensors – devices usually having two principal components:1) a thick (hundreds of microns) layer of some semiconductor material ({{chem2|SnO2}}, {{chem2|In2O3}}), called "matrix" and an upper layer of catalytically active additives like noble metals (Pd,{{Cite journal|title = Study of influence of palladium additives in nanosized tin dioxide on sensitivity of adsorption semiconductor sensors to hydrogen|journal = Sensors and Actuators B: Chemical|date = 2014-06-01|pages = 298–305|volume = 196|doi = 10.1016/j.snb.2014.02.019|first1 = Ludmila P.|last1 = Oleksenko|first2 = Nelly P.|last2 = Maksymovych|first3 = Evgeniy V.|last3 = Sokovykh|first4 = Igor P.|last4 = Matushko|first5 = Andrii I.|last5 = Buvailo|first6 = Norman|last6 = Dollahon| bibcode=2014SeAcB.196..298O }} Pt{{Cite journal|title = Portable electronic nose system with gas sensor array and artificial neural network|journal = Sensors and Actuators B: Chemical|date = 2000-07-25|pages = 49–52|volume = 66|issue = 1–3|doi = 10.1016/S0925-4005(99)00460-8|first1 = Hyung-Ki|last1 = Hong|first2 = Chul Han|last2 = Kwon|first3 = Seung-Ryeol|last3 = Kim|first4 = Dong Hyun|last4 = Yun|first5 = Kyuchung|last5 = Lee|first6 = Yung Kwon|last6 = Sung| bibcode=2000SeAcB..66...49H }}) and metal oxides ({{chem|Co|x|O|y}}{{Cite journal|title = Adsorption-semiconductor hydrogen sensors based on nanosized tin dioxide with cobalt oxide additives|journal = Sensors and Actuators B: Chemical|date = 2012-11-01|pages = 39–44|volume = 174|doi = 10.1016/j.snb.2012.07.079|first1 = Ludmila P.|last1 = Oleksenko|first2 = Nelly P.|last2 = Maksymovych|first3 = Andrii I.|last3 = Buvailo|first4 = Igor P.|last4 = Matushko|first5 = Norman|last5 = Dollahon| bibcode=2012SeAcB.174...39O }}) accelerating the hydrogen oxidation reaction on the surface, which makes the sensor response much faster. The role of "matrix" is to transduce the signal to the measurement system. Thick film sensors are more stable than thin film sensors in terms of signal drifting, but generally exhibit slower sensor response due to diffusion constraints into a thick layer. Thick film sensor technology is getting substituted by thin film approaches due to the increasing need for sensor integration into modern electronic systems. Thick film sensors require increased temperatures for their operation and therefore appear to be poorly compatible with digital electronics systems.
Chemochromic hydrogen sensors – Reversible and irreversible chemochromic hydrogen sensors include a smart pigment paint that visually identifies hydrogen leaks by a change in color. The sensor is also available as tape.{{cite web|url=http://www.detectape.com/|title=DetecTape H2 — Low Cost Visual Hydrogen Leak Detector|author=|date=|website=www.detectape.com|access-date=18 April 2018}} Other methods have been developed to assay biological hydrogen production.{{cite journal|title=Implementation of photobiological H2 production: the O2 sensitivity of hydrogenases|first=Maria L.|last=Ghirardi|date=1 September 2015|journal=Photosynthesis Research|volume=125|issue=3|pages=383–393|doi=10.1007/s11120-015-0158-1|pmid=26022106|s2cid=14725142}}
Diode based Schottky sensor – A Schottky diode-based hydrogen gas sensor employs a palladium-alloy gate. Hydrogen can be selectively absorbed in the gate, lowering the Schottky energy barrier.{{cite web|url=http://www.electrochem.org/dl/interface/spr/spr06/spr06_p66-69.pdf|title=Schottky energy barrier|author=|date=|website=electrochem.org|access-date=18 April 2018}} A Pd/InGaP metal-semiconductor (MS) Schottky diode can detect a concentration of 15 parts per million (ppm) {{chem2|H2}} in air.{{cite web|url=http://iopscience.iop.org/0268-1242/18/7/303|archive-url=https://archive.today/20120804174100/http://iopscience.iop.org/0268-1242/18/7/303|url-status=dead|title=A hydrogen sensing Pd/InGaP metal-semiconductor (MS) Schottky diode h…|date=4 August 2012|archive-date=4 August 2012|website=iop.org|access-date=18 April 2018}} Silicon carbide semiconductor or silicon substrates are used.
Metallic La-Mg2-Ni which is electrical conductive, absorbs hydrogen near ambient conditions, forming the nonmetallic hydride LaMg2NiH7 an insulator.{{cite web|url=http://www.biomedexperts.com/Abstract.bme/15783759/Hydrogenation-induced_insulating_state_in_the_intermetallic_compound_LaMg2Ni|title=Hydrogenation-induced insulating state in the intermetallic compound LaMg2Ni.|website=biomedexperts.com|access-date=18 April 2018|archive-url=https://web.archive.org/web/20120213100941/http://www.biomedexperts.com/Abstract.bme/15783759/Hydrogenation-induced_insulating_state_in_the_intermetallic_compound_LaMg2Ni|archive-date=2012-02-13|url-status=dead}}

Sensors are typically calibrated at the manufacturing factory and are valid for the service life of the unit.

=Enhancement=

Siloxane enhances the sensitivity and reaction time of hydrogen sensors. Detection of hydrogen levels as low as 25 ppm can be achieved; far below hydrogen's lower explosive limit of around 40,000 ppm.

References

External links

[https://web.archive.org/web/20060926184752/http://www.sandia.gov/mstc/technologies/microsensors/hydrogensensor.html Wide-Range Hydrogen Sensor ]
[https://web.archive.org/web/20160117052326/http://bit.or.at/irca/bbsshow8.php?ref1=OO%2FINTA%2F36&vQuelle=&bcc= Bragg type optic fibre sensor]
[http://www.eere.energy.gov/industry/sensors_automation/pdfs/h2_monitoring.pdf EERE success story H2scan]
[http://www.cna.com.tw/postwrite/cvpread.aspx?ID=57560 2010-NCKU-Semiconductor transistor-type hydrogen sensor]
[http://www.anl.gov/techtransfer/pdf/HydrogenSensorr&d100.pdf Argonne National Laboratory (Thin Film)]
[http://www.ika.rwth-aachen.de/r2h/index.php/Hydrogen_Sensor#_ref-0 Roads2HyCom]

Category:Sensors

Category:Hydrogen technologies

Category:Nanoelectronics

Category:Microtechnology