The sensor prepared by the Australian research team is able to distinguish ammonia from other gases with greater selectivity than other technologies (Shutterstock)
Hydrogen fuel is described as the "energy of the future", so it is expected that the demand for "ammonia" gas, which is one of the best ways to store hydrogen, will increase, which requires attention to the presence of devices that sense any leaks of this gas, in order to ensure safe operation, which is what engineers have done. Australians from the Royal Institute of Technology in Melbourne provided a solution, details of which were reported in the journal Advanced Functional Materials.
Ammonia, whose global production is estimated at about 235 million metric tons (one metric ton is equivalent to 1,000 kilograms), is used as a carrier in the hydrogen storage process known as "ammonia decomposition." In this process, it is thermally decomposed into its constituent elements, namely nitrogen and hydrogen, and the reaction can be catalyzed with various materials - usually at high temperatures - to enhance the efficiency of hydrogen release.
Although this method provides a way to store hydrogen, there are challenges associated with it, the most important of which is addressing safety concerns related to ammonia leakage, as the gas can pose many health risks such as irritation to the eyes, skin, and respiratory system, especially when exposed to it in high concentrations or for long periods. .
Ammonia acts as a carrier in the hydrogen storage process (Shutterstock)
Ammonia in human breath
Although human exposure to ammonia can be harmful, the gas is also present in human breath, and can serve as a biomarker for diagnosing many diseases such as kidney and liver-related disorders.
Ammonia is a byproduct of protein metabolism in the body, and is produced primarily in the liver as a result of the breakdown of amino acids. Under normal circumstances, the liver converts ammonia into urea, which the body then excretes through urine. But when liver function is damaged, such as in liver disease or failure, the liver may not be able to process ammonia efficiently, causing it to build up in the bloodstream.
Once ammonia accumulates in the bloodstream, it can spread to the lungs and be exhaled. This phenomenon is known as “ammonia odor.” Therefore, measuring its levels in the breath can provide valuable information about the functioning of the liver and kidneys, and high levels of it in the breath may indicate an imbalance. In the liver or other metabolic disorders that affect its metabolism.
Because the sensor prepared by the Australian research team for industrial purposes can measure small amounts of ammonia, it can also be used to detect the gas in people's breath to alert doctors to health disorders.
Ammonia builds up in the bloodstream when the liver cannot process it efficiently and is diagnosed with a blood test (Shutterstock)
Trace gas with electrical resistance
“The sensor is based on thin, transparent tin dioxide, which can easily track ammonia at much smaller levels than similar technologies,” said senior researcher at the Royal Institute of Technology in Melbourne and lead author of the study, Dr. Neetu Syed, in a statement issued by the institute.
She explains, “When ammonia is present in the air, it interacts with the tin oxide layer on the sensor, causing changes in its electrical resistance. The higher the ammonia concentration, the greater the change in resistance. This change is then measured by the sensor, allowing it to detect even small quantities.” of ammonia. In addition, the sensor is able to distinguish ammonia from other gases with greater selectivity than other technologies, so the sensor appears as if it is an electric nose.”
The team conducted experiments using their sensor in a specially designed room to test its ability to detect ammonia gas at different concentrations (5-500 ppm) under varying conditions, including temperature. They also tested the device's selectivity for ammonia against other gases, including Carbon dioxide and methane.
“Their miniature sensor provides a safer and less complicated way to detect toxic gas compared to current technologies,” said study co-researcher Chung Nguyen.
Researchers Neetu Syed (left), Ilyas Sabri (centre) and Chung Nguyen in their laboratory (Royal Institute of Technology, Melbourne)
Current methods for ammonia detection produce accurate measurements, but require expensive laboratory equipment with qualified technicians and sampling, and the process is often time-consuming and heavy equipment.
In addition, the manufacture of ammonia detection devices today involves expensive and complex processes to prepare sensitive layers for manufacturing sensors, and all these obstacles are overcome in the new sensor, as Nguyen explains.
How is the sensor made?
The new sensor is manufactured in simple, not complicated, steps, which study co-researcher Elias Sabry explains as follows:
First - Tin Dioxide Deposition:
The sensor begins with the deposition of transparent, atomically thin tin dioxide onto a base material, and this deposition is critical to the function of the sensor.
Second: Extracting the tin oxide layer:
The tin oxide layer is extracted directly from the surface of the molten tin at a temperature of 280 degrees Celsius. This process produces a thin layer of tin oxide.
Third - Achieving thinness:
The layer of tin oxide that we obtain is incredibly thin, as it is about 50 thousand times thinner than paper, and this extreme thinness is considered necessary for the sensitivity and effectiveness of the sensor.
Fourth - One synthetic step:
The manufacturing process includes only one synthetic step, and this simplicity is considered beneficial compared to other methods that may require multiple steps or complex procedures.
“The manufacturing process does not include the use of toxic solvents, and this ensures safety and reduces environmental impact,” says Sabry.
The sensor manufacturing process involves only one assembly step (Royal Institute of Technology, Melbourne)
Waiting for large scale experiments
The cost of producing the sensor, according to its manufacturing steps, appears to be quite low, and it is subject to development, allowing it to be produced in large quantities, for a variety of applications. But we must ensure that it works on a large scale with the same efficiency that appeared in the experiments, says Ayman Helmy, professor of chemical engineering at the Egyptian University of South Valley.
Helmy explains in a telephone conversation with Al Jazeera Net that ensuring that the sensor works in real-world applications requires tests of its effectiveness in detecting ammonia at different concentrations and under different environmental conditions.
He adds, "We must also ensure that it continues to work with the same efficiency and effectiveness in the long term, and this needs to be used in more than one experiment and over somewhat long periods of time."
Source: Al Jazeera + websites