Pencil-on-Paper Humidity Sensor Treated with NaCl Solution for Health Monitoring and Skin Characterization

Guangyu Niu, Zihan Wang, Ye Xue, Jiayi Yan, Ankan Dutta, Xue Chen, Ya Wang, Chaosai Liu, Shuaijie Du, Langang Guo, Peng Zhou, Huanyu Cheng, Li Yang

Research output: Contribution to journalArticlepeer-review

21 Scopus citations


Although flexible humidity sensors are essential for human health monitoring, it is still challenging to achieve high sensitivity and easy disposal with simple, low-cost fabrication processes. This study presents the design and fabrication of highly reliable hand-drawn interdigital electrodes from pencil-on-paper treated with NaCl solution for highly sensitive hydration sensors working over a wide range of relative humidity (RH) levels from 5.6% to 90%. The applications of the resulting flexible humidity sensor go beyond the monitoring of respiratory rate and proximity to characterizations of human skin types and evaluations of skin barrier functions through insensible sweat measurements. The sensor array can also be integrated with a diaper to result in smart diapers to alert for an early diaper change. The design and fabrication strategies presented in this work could also be leveraged for the development of wearable, self-powered, and recyclable sensors and actuators in the future.

Original languageEnglish (US)
Pages (from-to)1252-1260
Number of pages9
JournalNano letters
Issue number4
StatePublished - Feb 22 2023

All Science Journal Classification (ASJC) codes

  • Bioengineering
  • General Chemistry
  • General Materials Science
  • Condensed Matter Physics
  • Mechanical Engineering


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