High humidity sensing by ‘hygromorphic’ dielectric elastomer actuator

Milan Shrestha, Zhenbo Lu, Gih Keong Lau*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


Many capacitive or resistive humidity sensors cannot accurately measure high humidity because of surface water condensation and saturation of hygrosopic material in the sensors. Here, we propose a novel method of high humidity measurement using a ‘hydromorphic’ dielectric elastomer actuator (DEA). This novel humidity sensor consists of a ‘relatively water-inert’ acrylic dielectric elastomer layer (3M VHB 4910) sandwiched by a pair of hygroscopic polymer electrodes. The hygroscopic polymer electrodes are made of poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS); they become softer upon moisture absorption while enabling moisture permeation into the dielectric elastomer substrate during electrical activation and read-out. While the dielectric elastomeric actuation (under constant voltage) enlarged with increasing humidity, the current leaked through it rose more significantly. This suggests a strong humidity dependence of dielectric resistivity. Experimental correlation showed the dielectric resistance be a piecewise linear function of humidity. Further, this DEA-based humidity sensor remained working when both its electrodes were sprayed with a mist of water droplets.

Original languageEnglish
Article number129268
JournalSensors and Actuators, B: Chemical
StatePublished - 15 Feb 2021


  • 4-ethylenedioxythiophene) polystyrene sulfonate
  • Dielectric elastomer actuator
  • Humidity sensor
  • Poly(3
  • Resistive extensometer

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