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Butterfly Inspired Hydrogen Sensor Powered by Light

Philip Barnes
14 December 2020

Hydrogen Butterfly

Climate change and air quality concerns have pushed clean energy up the global agenda. As we switch over to new, cleaner technologies and fuels, our experience of using power, heat and transport are going to change, transforming the way we live, work and get from A to B.

Hydrogen is seen as a potential renewable energy source for the future. It can be used for heat and power, as part of the production of other chemicals, or to store energy for later use. Hydrogen can act as an energy store as a backup for renewable sources like solar power or wind power. But hydrogen comes with a number of potential risks. Hydrogen mixes well with air and explosive mixtures are easily formed. Heating it may cause violent combustion or explosion. It also reacts violently with air, oxygen, halogens and strong oxidants causing fire and explosion hazard. Using hydrogen safely by preventing leaks, adding a scent, transporting it carefully and controlled burning can help minimise these risks.

A recent article in The Engineer has highlighted that researchers at RMIT University in Melbourne Australia have developed a light powered hydrogen sensor inspired by the surface of butterfly wings aimed at mitigating some of these risks.

The sensor is said to produce ‘ultra-precise’ results at room temperature, detecting hydrogen leaks before they pose safety risks and could also measure small amounts of gas on people’s breath – a potentially useful tool in the diagnosis of gut disorders.

Commercial hydrogen sensors work at temperatures of 150 degrees C or higher, but the prototype developed by the RMIT team has been made up of tiny spheres called photonic or colloidal crystals. According to researchers, the hollow shapes are similar to minuscule bumps found on the surface of butterfly wings and are ‘ultra-efficient’ at absorbing light. This allows the sensor to draw all the energy it needs to operate from a beam of light, rather than heat.

The team’s findings, published in the journal ACS Sensors, suggest that the sensor can detect hydrogen at concentrations from as little as ten parts per million molecules (for medical diagnoses) to 40,000 parts per million (the level where gas becomes potentially explosive). 

“Hydrogen has the potential to be the fuel of the future but we know safety fears could affect public confidence in this renewable energy source,” said co-lead researcher Dr Ahmad Kandjani. “By delivering precise and reliable sensing technology that can detect the tiniest of leaks, well before they become dangerous, we hope to contribute to advancing a hydrogen economy that can transform energy supplies around the world.”

To make the sensor, an electronic chip is covered with a thin layer of photonic crystals and a titanium palladium composite. When hydrogen reacts with the chip, the gas is converted into water, creating an electric current. By measuring the magnitude of the current, the sensor can tell how much hydrogen is present. 

A provisional patent application has been filed for the technology, and the team now hope to collaborate with manufacturers of hydrogen sensors, fuel cells, batteries and medical diagnostic companies to commercialise the sensor. 

This story is adapted from an article in The Engineer, with editorial changes made by the METaL Project.