The scientists say that the “super thin” film of tin dioxide, which can be fitted to a flexible material, can detect ammonia at smaller quantities than similar technologies. (Source: RMIT)

Scientists Develop Small ‘Nose-Like’ Ammonia Gas Sensor

The sensor contains a ‘super thin’ film of tin dioxide that reportedly detects ammonia at smaller quantities than similar technologies.

Scientists in Australia have developed a proof-of-concept “nose-like” sensor for detecting small amounts of ammonia gas, according to a statement from the Royal Melbourne Institute of Technology (RMIT), one of the participating academic institutions.

The sensor, which includes a “super thin” film of tin dioxide, can “easily” detect ammonia at smaller quantities than similar technologies, explained the group of researchers from RMIT, the University of Melbourne and the Australian Research Council (ARC) Centre of Excellence for Transformative Meta-Optical Systems (TMOS).

“Our device acts like an electric ‘nose’ by efficiently detecting even the tiniest amount of ammonia,” added Dr. Nitu 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.”

Due to the toxicity of ammonia, the reliable and sensitive detection of the gas is vitally important for its safe use, noted the scientists.

While they highlighted its application in hydrogen storage and specialized medical diagnostic devices, it could also be adopted in the HVAC&R sector, where ammonia (R717) is commonly used in industrial refrigeration and cooling applications.

Electric ‘nose’

According to the scientists, the sensor works by measuring the electrical resistance of the tin dioxide film. When ammonia is present, the electrical resistance of the tin dioxide changes.

“The higher the level of ammonia, the greater the change in the resistance of the device,” they said.

To assess the device’s ability to sense ammonia at different quantities, the researchers tested it under various conditions, including temperatures. They found that the sensor is able to detect ammonia gas at concentrations of 5–500 parts per million, with a detection limit at the parts-per-billion level, as noted in a peer-reviewed article published by the scientists in Advanced Functional Materials.

The device is also able to differentiate ammonia from other gases, including carbon dioxide and methane, claim the scientists.

From left: Dr. Nitu Syed, Dr. Ylias Sabri and Dr. Chung K. Nguyen in their lab at RMIT. (Source: RMIT)
From left: Dr. Nitu Syed, Dr. Ylias Sabri and Dr. Chung K. Nguyen in their lab at RMIT. (Source: RMIT)

Compared to existing technologies, the newly developed “miniaturized” sensor offers a safer, less cumbersome and cost-effective method of “instantaneously” detecting dangerous levels of ammonia gas, explained RMIT’s Dr. Chung Nguyen.

“Current approaches to ammonia detection produce accurate measurements but require expensive laboratory equipment with qualified technicians, extensive sampling and preparation,” he added. “This process is often time-consuming and not portable due to the size of the equipment needed.”

The team has also successfully fixed the tin dioxide film, which is transparent and 50,000 times thinner than paper, to flexible base materials, which is something others have struggled to achieve, they said.

To demonstrate the “high-performing capabilities” of the sensor, the scientists are looking to work with industry partners to develop the technology further and produce a prototype.

The research was funded by ARC with support from the National Computational Infrastructure, the Microscopy and Microanalysis Facility and Micro Nano Research Facility at RMIT and the University of Melbourne’s Department of Chemical Engineering and School of Physics.

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