Electroactive Polymers (EAPs)

Electroactive polymers (EAPs) are typical soft active material that can response to external electric stimuli. Dielectric elastomer (DE) is one of the representative EAPs and is widely used as an actuator or sensor. It is actually a sandwiched structure that consists of one single elastomer film and complaint electrodes on both surfaces. Subject to an external electric field, DE will reduce in thickness and expand in area due to Maxwell’s stress. When the electric field is revoked, it can restore to its original shape.

Fig.1 Schematic of a dielectric elastomer membrane subjected to forces and an electric voltage.

Based on this property, DE can be used to create intelligent transducer and has long been desired for the development of aerospace,  mechanical engineering, artificial muscle, biologically inspired robots, and biomedicine. Our group focuses on synthesis, actuator design, constitutive theory, and stability of dielectric elastomers.

(a) In order to offer guidance in the design and fabrication of excellent actuators featuring dielectric elastomers, we investigate constitutive models, large deformations, electromechanical instabilities, snap-through instabilities, thermo-electro-mechanical instabilities and typical failure models of dielectric elastomers and their composites.

(b) The BaTiO3 based dielectric elastomer composite is fabricated and tested. The stress–strain relationship, dielectric constant and the electro-induced deformation of carbon nanotube based dielectric elastomer composite is also demonstrated.

(c) We have fabricated the rolled, folded, inflated and stacked actuators of dielectric elastomers and their mechanical and electrical properties are also investigated. Based on the stacked dielectric elastomer actuator, the energy harvest device and Braille display are designed and fabricated, and their performance demonstration is subsequently conducted.

Fig.2 Nominal electric field and stretch of dielectric elastomer undergoing polarization saturation

Fig.3 Energy harvesting device using stacked dielectric elastomer actuators