Researchers in Sweden have unveiled a new hydrogen sensor which is resistant to humid environments. Chalmers University of Technology recognised how hydrogen sensors do not usually work well in humidity, because where hydrogen is present there is often humidity.
Hydrogen is an increasingly important energy carrier in the transport sector and is used as a raw material in the chemical industry or for green steel manufacturing.
Safety first
Safety sensors are needed to detect leaks and prevent the formation of flammable oxyhydrogen gas when hydrogen is mixed with air.
In addition to water being constantly present in ambient air, it is also formed when hydrogen reacts with oxygen to generate energy, for example in a fuel cell that can be used in hydrogen-powered vehicles and ships. Furthermore, fuel cells themselves require water to prevent the membranes that separate oxygen and hydrogen inside them from drying out.
Facilities where hydrogen is produced and stored are also constantly in contact with the surrounding air, where humidity varies greatly over time depending on temperature and weather conditions. Therefore, to ensure the volatile hydrogen gas does not leak and create flammable oxyhydrogen, reliable humidity-tolerant sensors are needed here as well.
Hydrogen sensor
The new humidity-tolerant hydrogen sensor from Chalmers fits on a fingertip and contains tiny particles – nanoparticles – of the metal platinum. The particles act as both catalysts and sensors at the same time. This means that the platinum accelerates the chemical reaction between hydrogen and oxygen from the air, which leads to heat development that causes the humidity, in the form of a film of water on the sensor surface, to ‘boil away’.
The amount of hydrogen in the air determines how much of the water film boils away, and the moisture content in the air controls the thickness of the film. It is therefore possible to measure the concentration of hydrogen by measuring the thickness of the water film.
The sensor detects hydrogen down to the ‘parts per million’ range: 30 ppm which is three thousandths of a per cent, making it one of the world’s most sensitive hydrogen gas sensors in humid environments.
Hours of research
Chalmers doctoral student and lead author of an article in the journals ACS Sensors, Athanasios Theodoridis, said: “We tested the sensor for over 140 hours of continuous exposure to humid air. The tests showed that it is stable at various given degrees of humidity and can reliably detect hydrogen gas in these conditions, which is important if it is to be used in real-world environments.”
Mr Theodoridis is the lead author of an article in the journals ACS Sensors.
Christoph Langhammer, Professor of physics at Chalmers, said: “There is currently strong demand for sensors that perform well in humid environments. As hydrogen plays an increasingly important role in society, there are growing demands for sensors that are not only smaller and more flexible, but also capable of being manufactured on a large scale and at a lower cost. Our new sensor concept satisfies these requirements well.”
Mr Langhammer is one of the founders of the sensor company Insplorion, where he now serves in an advisory capacity.
He added: “We expect to need to combine different types of active materials to create sensors that perform well regardless of the environment. We now know that certain materials provide speed and sensitivity, while others are better able to withstand humidity. We are now working to apply this knowledge going forward.”
