Zipping it up: DEAs independent of the elastomer's electric breakdown field

Abstract

We demonstrate here an alternative dielectric elastomer actuator (DEA) structure, which relies on the compliant nature of elastomer membranes but does not require any electric field in the elastomer. Our elastomer zipping device is a macroscopic version of the electrostatic zipping actuators common in silicon MEMS. It consists of a cm-sized metallic bottom electrode, covered by a thin insulator, on which the elastomer membrane is bonded, enclosing a tapered air gap. A compliant electrode is patterned on the lower face of the elastomer membrane. Applying a voltage between solid bottom electrode and compliant electrode leads to controlled pull-in in movement, comparable to the closing of a zipper, thus giving large strokes and forces with no electrical requirements on the elastomer since no voltage is applied across the membrane. The compliant electrodes (20 mm diameter) are produced by metal ion-implantation into the elastomer membranes. The bottom metal electrodes are coated with 10 to 30 µm of Al 2 O 3 . We report on our experimental study of membrane deflection and dynamics and discuss the effect of design parameters such as elastomer mechanical properties and actuator geometry. Membrane deflection of up to 1.4 mm was reached at only 200 V actuation voltage. The large membrane deformation achieved with this zipping actuation can be applied to applications such as pumps or tunable liquid lenses. The out-of plane movement of the membrane can be used for linear actuation.

Mm-size bistable zipping dielectric elastomer actuators for integrated microfluidics

“…As demonstrated experimentally by Gebbers et al [11] , it is possible to fabricate DEA zipping actuators based on this same principle: the soft electrode is pulled in hard contact with the rigid dielectric, and the electric field is therefore applied across a few μm thick rigid insulator. Since solid dielectric coatings such as silicon nitride, silicon oxide or aluminum oxide have high dielectric constants and breakdown strengths, the actuation voltage can be greatly reduced.…”

“…As presented in our previous work [10,11] , DEA zipping actuators are a variant of the traditional DEA operation mode inspired by silicon MEMS zipping devices [12] . Instead of having two compliant electrodes that squeeze the elastomer and produce a thickness compression and lateral expansion [1] , zipping DEAs attract one single compliant electrode toward a rigid one.…”

Zipping dielectric elastomer actuators: characterization, design and modeling

“…As a direct consequence, the actuation is no more limited by the breakdown field of the membrane but by the rigid dielectric. This family of zipping devices were studied experimentally by Gebbers et al [26]. …”

“…As also pointed out in previous work [27], variants of the measured zipping DEA structure are also possible. Instead of being applied across the membrane, the electric field can also build up across a solid layer deposited on the rigid electrode or a stack of both [26,28,39]. Hybrid actuators including squeezing and zipping modes might also be of particular interest.…”

“…Unlike the conventional DEA actuation mechanism, the elastomer membrane of a zipping DEA is not squeezed by the electrostatic force between two compliant electrodes, but a single soft electrode is attracted toward a fixed one (figure 2A). For an alternate zipping geometry modeled but not studied experimentally in this work, the operating voltage can be significantly reduced using a thin high quality rigid dielectric [26,27].…”