High humidity sensing by ‘hygromorphic’ dielectric elastomer actuator

[Display omitted] •Hygroscopic PEDOT:PSS electrodes and acrylic dielectric elastomer make a 'hygromophic' actuator•The current leaked via this constant-voltage activated capacitor surges with increasing humidity Many capacitive or resistive humidity sensors cannot accurately measure high h...

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Bibliographic Details
Published in:Sensors and actuators. B, Chemical Chemical, 2021-02, Vol.329, p.129268, Article 129268
Main Authors: Shrestha, Milan, Lu, Zhenbo, Lau, Gih-Keong
Format: Article
Language:English
Subjects:
4-ethylenedioxythiophene) polystyrene sulfonate
Actuation
Actuators
Condensates
Dielectric elastomer actuator
Dielectric strength
Elastomers
Electrodes
Humidity
Humidity measurement
Humidity sensor
Linear functions
Moisture
Moisture absorption
Poly
Polymers
Polystyrene resins
Resistive extensometer
Sensors
Substrates
Surface water
Water drops
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Summary:[Display omitted] •Hygroscopic PEDOT:PSS electrodes and acrylic dielectric elastomer make a 'hygromophic' actuator•The current leaked via this constant-voltage activated capacitor surges with increasing humidity 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.
ISSN:0925-4005
1873-3077
DOI:10.1016/j.snb.2020.129268