A flexible ammonia gas sensor in the form of plastic has been developed using a simple solution process at low temperatures, and it is expected that it will be used in wearable environmental monitoring devices and disease diagnosis sensors in the future.

A research team led by Dr. Jong-won Yoon, Dr. Jeong-dae Kwon, and Dr. Yong-hoon Kim from the Energy and Environmental Materials Research Center of the Korea Institute of Materials Science (KIMS, President Cheol-jin Choi) has developed the world's first ammonia (NH3) gas sensor based on a copper bromide film (CuBr) that can be manufactured through a simple solution process at low temperatures.

This technology is an achievement that has realized the flexibility of the sensor, high sensitivity and high selectivity performance, and even reduced production costs.

Ammonia gas sensors detect ammonia in the air and are used for indoor and outdoor environmental monitoring, detection of hazardous gases in industrial sites, and disease diagnosis.

The copper bromide film used in the sensor changes its electrical resistance significantly when it comes into contact with ammonia, allowing it to detect even low concentrations of ammonia.

Previously, the process of forming the copper bromide film required for the sensor required a high-temperature vacuum process of over 500℃, which made it difficult to apply to flexible substrates vulnerable to high temperatures and had the disadvantage of high manufacturing costs.

To solve this problem, the research team developed a technology to form two-dimensional copper nanosheets on a substrate without a vacuum process at a low temperature of 150℃ or less and to synthesize a copper bromide film only through a simple solution process.

As a result, we successfully implemented an ammonia gas sensor on a plastic substrate.

This study has developed a high-sensitivity sensor that can detect ammonia concentrations of less than one part per million using a low-temperature solution process, which has the advantage of significantly reducing production costs and being usable as a wearable sensor or diagnostic medical device.

In fact, it was confirmed that the sensor operates stably while maintaining high performance through experiments in which it was repeatedly bent more than 1,000 times.

Senior Researcher Jong-won Yoon, the principal investigator of the study, said, “The ammonia sensor developed through this study has high potential to be expanded into flexible, wearable devices, and can be utilized in various fields from indoor air quality monitoring to personal health management.” He added, “In particular, it is expected to be applied as a disease diagnosis sensor that attaches to the human body to analyze exhaled breath.”

Meanwhile, the research team conducted the study together with the research teams of Professor Tae-wook Kim of Jeonbuk National University and Professor Hong-seung Kim of Korea Maritime and Ocean University.

This research achievement was supported by the Global TOP Project of the National Research Council of Science and Technology, the Nano and Material Technology Development Project of the National Research Foundation of Korea, and the Major Project of the Korea Institute of Materials Science, and was published online on March 6 in the international academic journal Sensors and Actuators B: Chemical (IF: 8.0, JCR Top 0.7%). The research team is continuously conducting additional research in the form of large-area films to improve productivity.