Carbon Trends (Apr 2022)

Printed, all-carbon-based flexible humidity sensor using a cellulose nanofiber/graphene nanoplatelet composite

  • Ayako Yoshida,
  • Yi-Fei Wang,
  • Shogo Tachibana,
  • Ayuka Hasegawa,
  • Tomohito Sekine,
  • Yasunori Takeda,
  • Jinseo Hong,
  • Daisuke Kumaki,
  • Takeo Shiba,
  • Shizuo Tokito

Journal volume & issue
Vol. 7
p. 100166

Abstract

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Eco-friendly flexible humidity sensors with high sensing performance are desired for the next-generation wearable electronics. In this work, we developed a high-performance fully printed flexible humidity sensor using all-carbon functional materials. The electrodes and sensing layer of the sensor were printed using all-carbon-based cellulose nanofiber/graphene nanoplatelet (CNF/GNP) composites. The newly developed CNF/GNP ink can be prepared by simple mixing without any complex processes. These sensors showed a high resistive response of 240% over the relative humidity (RH) range of 30% to 90%, with response and recovery times of 17 s and 22 s, respectively, and good mechanical flexibility. Since CNF and GNPs are abundant in nature, degradable, and biocompatible, this work suggests the possibility of manufacturing inexpensive, eco-friendly sensors with high performances. As a proof-of-concept, we demonstrate the application of our sensor in human respiration detection, non-contact proximity sensing, and baby-diaper wetness monitoring.

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