Even the smallest gas concentrations are detected – Australian researchers see widespread use

A tiny electronic sniffer nose can be used to reliably detect the corrosive and toxic ammonia gas. It can be used in both the medical and energy sectors, according to the development by RMIT University (https://www.rmit.edu.au) and the ARC Centre of Excellence for Transformative Meta-Optical Systems (https://www.tmos.org.au) at the University of Melbourne (https://www.unimelb.edu.au/). “Our sensor can detect even the smallest concentrations of ammonia. It is also able to detect ammonia more selectively than previously used sensors,” says research leader Nitu Syed.

Thin zinc oxide film at the heart

The centrepiece is a wafer-thin film of tin oxide that is integrated into an electrical circuit. When it comes into contact with ammonia, its electrical resistance changes, which of course does not go unnoticed by the circuit. It indicates the change, which is proportional to the concentration of the gas.
Every year, 235 million tonnes of ammonia are produced worldwide, which is mainly used in the manufacture of fertilisers. The sensor could be used to protect employees both in the chemical industry, which produces the gas, and by fertiliser manufacturers. However, this area could expand considerably. Ammonia is considered one of the best carriers of hydrogen for transport. The sensor could therefore be used in solar and wind farms with associated ammonia production, on tankers that transport the gas in liquid form and at the terminals where the cargo is unloaded.

Sensor even “smells” diseases

Ammonia is harmful to humans. However, the gas is also present in low concentrations in the air we breathe. This biomarker can be used to diagnose kidney and liver diseases. As the new sniffer nose detects even the lowest concentrations, it can also be used in medicine. “Although current ammonia detection devices are very accurate, they require expensive laboratory equipment and qualified technicians as well as extensive sampling and preparation,” says Syed’s colleague Chung K. Nguyen.
The production of the sensor is very simple. “We obtain the tin oxide film directly from the surface of molten tin at 280 degrees Celsius,” reveals RMIT engineering scientist Ylias Sabri. “This film is 50,000 times thinner than paper. We only need a single synthesis step, without toxic solvents, vacuum or bulky and expensive instruments.”