Nucleation and propagation of voltage-driven wrinkles in an inflated dielectric elastomer balloon.

Dielectric elastomer (DE) transducers frequently undergo voltage-induced large deformation, which may lead to mechanical instabilities. Here, we investigate wrinkle formation and propagation on the surface of a DE membrane mounted on an air chamber and subjected to a step voltage. Our experiments show that the geometric characteristics of the wrinkle morphology and the nucleation sites depend on the inflation pressure and the applied voltage. As the inflation pressure increases, the critical voltage used to nucleate the wrinkle decreases, while the location where the wrinkle nucleates shifts from the center to the boundary of the membrane. Moreover, by increasing the amplitude of the applied voltage, wrinkle morphology changes from stripe-like wrinkles to labyrinth-like wrinkles. Furthermore, we develop an analytical model to validate the experimental observations and map out the various wrinkle morphologies as a function of the applied pressure and voltage. A three dimensional phase diagram is constructed to help design new soft actuators.