Choi, Seon-Jin Yu, Hayoung Jang, Ji Soo Kim, Min-Hyeok Kim, Sang-Joon Jeong, Hyeon Su Kim, Il-Doo 2024-01-19T23:30:15Z 2024-01-19T23:30:15Z 2021-09-03 2018-03 1613-6810 https://pubs.kist.re.kr/handle/201004/121654 Humidity sensors are essential components in wearable electronics for monitoring of environmental condition and physical state. In this work, a unique humidity sensing layer composed of nitrogen-doped reduced graphene oxide (nRGO) fiber on colorless polyimide film is proposed. Ultralong graphene oxide (GO) fibers are synthesized by solution assembly of large GO sheets assisted by lyotropic liquid crystal behavior. Chemical modification by nitrogen-doping is carried out under thermal annealing in H-2(4%)/N-2(96%) ambient to obtain highly conductive nRGO fiber. Very small (approximate to 2 nm) Pt nanoparticles are tightly anchored on the surface of the nRGO fiber as water dissociation catalysts by an optical sintering process. As a result, nRGO fiber can effectively detect wide humidity levels in the range of 6.1-66.4% relative humidity (RH). Furthermore, a 1.36-fold higher sensitivity (4.51%) at 66.4% RH is achieved using a Pt functionalized nRGO fiber (i.e., Pt-nRGO fiber) compared with the sensitivity (3.53% at 66.4% RH) of pure nRGO fiber. Real-time and portable humidity sensing characteristics are successfully demonstrated toward exhaled breath using Pt-nRGO fiber integrated on a portable sensing module. The Pt-nRGO fiber with high sensitivity and wide range of humidity detection levels offers a new sensing platform for wearable humidity sensors. English Wiley - V C H Verlag GmbbH & Co. Nitrogen-Doped Single Graphene Fiber with Platinum Water Dissociation Catalyst for Wearable Humidity Sensor. Article 10.1002/smll.201703934 1 Small, v.14, no.13 Small 14 13 N scie scopus 000428797800020 2-s2.0-85044576922 Chemistry, Multidisciplinary Chemistry, Physical Nanoscience & Nanotechnology Materials Science, Multidisciplinary Physics, Applied Physics, Condensed Matter Chemistry Science & Technology - Other Topics Materials Science Physics Article DENSITY-FUNCTIONAL THEORY CHEMICAL SENSORS LIQUID-CRYSTALS EXHALED BREATH OXIDE FIBERS DIAGNOSIS FILM TECHNOLOGIES ADSORPTION EFFICIENCY breath analysis catalysts humidity sensors graphene fibers nitrogen doping