Prof. Wi Hyoung Lee’s Team Develops ‘Ultrasensitive N-channel Graphene Gas Sensors’
Prof. Wi Hyuoung Lee from Department of Chemical Engineering and Researcher Bitnoori Kwon (first author, Master’s Degree at Department of Organic and Nano System Engineering) at Konkuk University announced on the 7th that they have developed ‘ultrasensitive n-channel graphene gas sensors’ that can detect harmful gasses of the human body in real-time-while maintaining its unique characteristics. (Thesis title: “Ultrasensitive N Channel Graphene Gas Sensors by Nondestructive Molecular Doping”) The research was published online on February 3rd in ACS Nano (IF=15.881), the authoritative journal in the field of nanotechnology.

As the importance of wearable sensors is becoming greater in the era of IoT, the development of light and high-performance sensors without using hard materials like silicon is drawing attention. It is necessary to develop sensors that detects NOx gas, which is harmful to our health, however, there are restrictions due to its high driving temperature, low sensitivity/selectivity.

As to this issue, the research team manufactured graphene sensors that react even at a concentration of ppq (a unit of 1000 trillionths, 10-15) or less by using graphene, which is known as a conductive material of a single layer of carbon.

The research team doped graphene with amine molecules rich in electrons to improve the sensitivity and selectivity of graphene to nitrogen dioxide (Figure a). Throughout the method, they confirmed that graphene rich in electrons increases absorption of oxidizing gases such as nitrogen dioxide, which lacks electrons, but decreases absorption of reducing gases such as ammonia. The finding was proved by the calculation result of Prof. Hoonkyung Lee’s team at Department of Physics. The sensitivity of graphene to nitrogen dioxide stayed at the level of ppb (a unit of 1 billionth, 10-9) before molecular doping, however, it showed a sensitivity of ppq (10-15), the highest level of the same material, after molecular doping (Figure b).

Prof. Lee said, “The research has suggested a paradigm that can secure great sensitivity and selectivity to oxidizing gas while maintaining its own transparency and flexibility through molecular doping,” and, “It is expected to be used in a variety of IoT fields including flexible display, healthcare devices and wearable sensors.”

Researcher Bitnoori Kwon, the first author of the thesis, has graduated from Department of Chemical Engineering for her bachelor’s degree and Department of Organic and Nano System Engineering for master’s degree at Konkuk University, continuing her career as a researcher of KIST. The research was conducted with the support of the Ministry of Science and Technology’s basic research project (intermediate research) and the Ministry of Trade, Industry and Energy’s ICT convergence fiber manufacturing process.