Flexible ammonia sensor detects gas with ultra-sensitivity and low cost

A research team has successfully developed the world’s first ammonia (NH₃) gas sensor based on a copper bromide (CuBr) film that can be fabricated through a simple solution process at low temperatures. The findings are published online in Sensors and Actuators B: Chemical.

This breakthrough technology not only enables sensor flexibility, ultra-sensitivity, and high selectivity but also significantly reduces manufacturing costs.

Ammonia gas sensors detect airborne ammonia and are utilized in indoor and outdoor environmental monitoring, hazardous gas detection in industrial settings, and disease diagnosis. The copper bromide (CuBr) film used in the sensor exhibits a significant change in electrical resistance upon exposure to ammonia, enabling the detection of even low concentrations of the gas.

In conventional methods, forming the copper bromide (CuBr) film required for the sensor necessitates a high-temperature vacuum process above 500°C. This poses challenges in applying it to flexible substrates, which are vulnerable to heat, and also leads to high production costs.

To address this issue, the research team led by Dr. Jongwon Yoon, Dr. Jeongdae Kwon, and Dr. Yonghoon Kim from the Energy & Environmental Materials Research Division at the Korea Institute of Materials Science (KIMS), developed a technique to form a two-dimensional copper nanosheet on a substrate at a temperature below 150°C without a vacuum process.

They then synthesized the copper bromide film through a simple solution-based process. As a result, they successfully implemented an ammonia gas sensor on a plastic substrate.

This study successfully developed a highly sensitive sensor capable of detecting ammonia concentrations as low as one part per million (ppm) using a low-temperature solution-based process. This breakthrough significantly reduces manufacturing costs and offers potential applications in wearable sensors and diagnostic medical devices.

Furthermore, experimental tests involving over 1,000 repeated bending cycles confirmed that the sensor maintained high performance and operated with stable functionality.

Dr. Jongwon Yoon, the lead researcher, stated, “The ammonia sensor developed through this study has great potential for expansion into flexible and wearable devices. It can be utilized in a wide range of applications, from indoor air quality monitoring to personal health management.”

“In particular, we expect that it could be applied as a disease diagnosis sensor by attaching it to the human body to analyze exhaled breath.”