Ultra-thin Glass Based Flexible, Transparent and Ultra-sensitive Surface Acoustic Wave Humidity Sensor with ZnO Nanowires and Graphene Quantum Dots

Research output: Contribution to journalArticle



  • Jianhui Wu
  • changshuai Yin
  • Jian Zhou
  • Honglang Li
  • Yi Liu
  • Yiping Shen
  • Sean Garner
  • Richard Fu
  • Huigao Duan

External departments

  • Hunan University


Original languageEnglish
Pages (from-to)39817–39825
JournalACS Applied Materials and Interfaces
Issue number35
Early online date10 Aug 2020
Publication statusPublished - 2 Sep 2020
Publication type

Research output: Contribution to journalArticle


Flexible electronic devices are normally based on organic polymer substrate. In this work, ultra-thin glass based flexi-ble, transparent and ultra-sensitive ZnO/glass surface acous-tic wave (SAW) humidity sensor is developed using a compo-site sensing layer of ZnO nanowires (NWs) and graphene quantum dots (GQDs). It shows much larger effective elec-tromechanical coupling coefficients and signal amplitudes, compared with those of flexible polymer based SAW devices reported in literature. Attributed to large specific surface are-as of ZnO NWs, large numbers of hydrophilic functional groups of GQDs, as well as the formation of p-n heterojunc-tions between GQDs and ZnO NWs, the developed ZnO/glass flexible SAW sensor shows an ultra-high humidity sensitivity of 40.16 kHz/%RH, along with its excellent stability and re-peatability. This flexible and transparent SAW sensor has demonstrated insignificant deterioration of humidity sensing performance, when it is bent on a curved surface with a bend-ing angle of 30, revealing its potential applications for sens-ing on curved and complex surfaces. The humidity sensing and human breathing detection have further been demon-strated for wearable electronic applications using ultra-thin glass based devices with completely inorganic materials.