Ammonia gas is one of the most widely produced chemicals in the world and plays a major role in modern life.
It is used in fertilizers that help grow food, in refrigeration systems, as a potential clean fuel, and even as a marker in medical testing.
However, ammonia can also be extremely dangerous. High levels of exposure can irritate the eyes and lungs, cause chest pain, lead to fluid buildup in the lungs, and in severe cases, result in death.
Because of these risks, industries that use ammonia need reliable ways to detect leaks quickly.
Over the years, scientists have developed portable and wearable sensors that can detect ammonia gas.
Some sensors measure changes in electrical resistance when gas is present, allowing for fast detection.
Others rely on color changes that are easy to see with the naked eye and are less affected by humidity.
Each approach has drawbacks.
Electrical sensors can be unstable or respond to other gases, while color-changing sensors can take a long time to return to normal after exposure. Researchers have been searching for a better solution that combines the strengths of both methods.
A team led by Professor Hyun Il Kang at Hanbat National University in South Korea has now developed a new wearable ammonia sensor designed to do exactly that. Their device is flexible, stretchable, and can be worn directly on the skin.
It uses a dual-mode system that provides both an electronic signal and an instant color change when ammonia is present.
The sensor is built on a breathable nanofiber material that allows gas to pass through easily, helping it detect even low concentrations.
The device works by pairing two sensing layers. One layer changes color using a dye that reacts to ammonia, giving a quick visual warning.
The other layer measures electrical changes caused by the gas, providing a precise reading.
Because both systems operate together, the sensor remains accurate even if one method is affected by environmental conditions. Tests showed that the device continues to function well in humid air and while being stretched or bent, conditions that often cause problems for wearable electronics.
Researchers believe this technology could have many practical uses. Workers in factories, cold storage facilities, farms, and livestock operations could wear the sensor to receive early warnings of dangerous leaks.
It could also be used in transportation systems that store ammonia as a fuel. In the future, the sensor might even help monitor health by detecting ammonia levels in a person’s breath, which can signal certain medical conditions.
Looking ahead, scientists hope this type of skin-mounted sensor could become part of “smart” protective equipment that continuously monitors the environment. By providing simple visual alerts along with electronic data, the technology could improve safety and reduce injuries caused by toxic gas exposure.
The same approach may also be adapted to detect other harmful substances, opening the door to new tools for environmental monitoring and preventive health care.
