Nose-like sensor sniffs out toxic ammonia gas

SKIP TO CONTENT

Nose-like sensor sniffs out toxic ammonia gas

Engineers in Australia have developed a small ammonia gas sensor that could enable safer hydrogen storage and specialised medical diagnostic devices.

The simple yet effective proof-of-concept sensor described in top academic journal Advanced Functional Materials is the result of collaboration by researchers at RMIT University, the University of Melbourne and the ARC Centre of Excellence for Transformative Meta-Optical Systems (TMOS).

Exposure to high levels of ammonia can lead to chronic lung conditions and irreversible organ damage.

An estimated 235 million metric tonnes of ammonia are produced around the world annually, but with ammonia being touted as one of the best ways to store hydrogen for clean fuel we may be seeing a lot more of it.

Reliable and sensitive ammonia detection will be essential to quickly spot potentially dangerous leaks of ammonia gas during transportation of hydrogen, to ensure safe operation.

But while human exposure to ammonia can be harmful, the gas is also found in human breath and can serve as a vital biomarker for diagnosis of many diseases such as kidney and liver-related disorders.

Given that the team’s sensor can measure tiny amounts of ammonia, it could be engineered to detect the gas on people’s breath to alert doctors to health disorders.

Lead researchers Dr Nitu Syed, Dr Ylias Sabri and Dr Chung K. Nguyen (left to right) in their lab at RMIT University. Credit: Seamus Daniel, RMIT

Lead researchers Dr Nitu Syed, Dr Ylias Sabri and Dr Chung K. Nguyen (left to right) in their lab at RMIT University. Credit: Seamus Daniel, RMIT

How the sensor works

Senior lead researcher Dr Nitu Syed said the sensor featured atomically thin transparent tin dioxide that can easily track ammonia at much smaller levels than similar technologies.

“Our device acts like an electric ‘nose’ by efficiently detecting even the tiniest amount of ammonia,” said Syed, McKenzie Research Fellow from the University of Melbourne, RMIT and TMOS.

“The sensor is also able to distinguish ammonia from other gases with more selectivity than other technologies.”

The presence of ammonia in the air changes the electrical resistance of the tin oxide film in the sensor: the higher the level of ammonia, the greater the change in the resistance of the device.

The team conducted experiments with their sensor in a specially designed chamber to test its ability to detect ammonia gas at various concentrations (5 – 500 parts per million) under different conditions, including temperature. They also tested the device’s selectivity of ammonia against other gases, including carbon dioxide and methane.

First author, Dr Chung K. Nguyen from RMIT, said their miniaturised sensor offered a safer and less cumbersome way to detect the toxic gas, compared to existing techniques.

“Current approaches to ammonia detection produce accurate measurements but require expensive laboratory equipment with qualified technicians, extensive sampling and preparation,” Nguyen said.

“This process is often time-consuming and not portable, due to the size of the equipment needed. In addition, the manufacturing of today’s ammonia detectors involves expensive and complicated processes to prepare sensitive layers for sensor fabrication.”

The team’s new sensor can instantaneously differentiate between safe and dangerous levels of ammonia in the environment, Nguyen said.

“The reproducible deposition of tin oxide also offers the opportunity for cost-effective mass production of sensing devices,” he said.

The team used a low-cost and scalable technique to deposit super thin tin dioxide onto a base material – even on a flexible material, which other approaches had challenges achieving. Credit: Seamus Daniel, RMIT

The team used a low-cost and scalable technique to deposit super thin tin dioxide onto a base material – even on a flexible material, which other approaches had challenges achieving. Credit: Seamus Daniel, RMIT

How the sensor is made

Co-senior lead researcher Dr Ylias Sabri, from RMIT’s School of Engineering, said the team used a low-cost and scalable technique to deposit super thin tin dioxide onto a base material – even on a flexible material, which other approaches had challenges achieving.

“We directly harvest a tin oxide film from the surface of molten tin at 280 degrees Celsius. The film is 50,000 times thinner than paper,” Sabri said.

“Our approach only requires a single synthesis step, without using any toxic solvents, vacuum, or bulky and expensive instruments.”

Next steps

The team is keen to collaborate with industry partners to further develop and prototype the sensor to demonstrate its high-performing sensing capabilities.

“The fabrication method aligns well with existing silicon industry manufacturing processes, making it suitable for mass production.”

Support for the research

The Australian Research Council funded the research, which was also supported by the National Computational Infrastructure, as well as the Microscopy and Microanalysis Facility (RMMF) and Micro Nano Research Facility (MNRF) at RMIT and the Department of Chemical Engineering and School of Physics at the University of Melbourne.

The researchers’ peer-reviewed article, “Instant-in-Air Liquid Metal Printed Ultrathin Tin Oxide for High-Performance Ammonia Sensors”, is published in Advanced Functional Materials (DOI: 10.1002/adfm.202309342).

Story: Will Wright

Society and Environment

01 February 2024

Share

Return to RMIT News

Society and Environment

01 February 2024

Share

Advanced Materials
STEM
Industry
Research
Engineering
Nano & Microtechnology
Environment
Science and technology

Engage

Contact RMIT News

Find an expert

Study with us

Research at RMIT

Related News

TREMS Hub delivers on circular economy mission

The ARC Industrial Transformation Research Hub for the Transformation of Reclaimed Waste Resources to Engineered Materials and Solutions for a Circular Economy (TREMS) has overseen close to 50 projects since its inception, helping to address Australia’s urgent waste crisis.

‘Invisible’ tweak could help make protein shakes less clumpy

Scientists from RMIT University and Riga Technical University in Latvia have shown that static change left on surfaces can be controlled, which may have big benefits for companies needing to avoid the little zap in production of common household goods.

RMIT and Moeve advance their collaboration to support energy transition

The partners marked a milestone event in Madrid, highlighting joint research activity and opportunities for future collaboration.

RMIT recognised at 2026 Good Design Awards

Eight projects featuring RMIT design research, outcomes and collaborations have been honoured at the 2026 Australian Good Design Awards.

Show more

aboriginal flag float-start

torres strait flag float-start

Acknowledgement of Country

RMIT University acknowledges the people of the Woi wurrung and Boon wurrung language groups of the eastern Kulin Nation on whose unceded lands we conduct the business of the University. RMIT University respectfully acknowledges their Ancestors and Elders, past and present. RMIT also acknowledges the Traditional Custodians and their Ancestors of the lands and waters across Australia where we conduct our business - Artwork 'Sentient' by Hollie Johnson, Gunaikurnai and Monero Ngarigo.

More information