dielectric elastomer

Recent experiments have shown that a voltage can induce a large deformation in an elastomer of interpenetrating networks. We describe a model of interpenetrating networks of long and short chains. As the voltage ramps up, the elastomer may undergo a snap-through instability. The network with long chains fills the space and keeps elastomer compliant at small to modest deformation. The network with short chains acts as a safety net that restrains the elastomer from thinning down excessively, averting electrical breakdown.  It appears possible to find a dielectric elastomer capable of giant deformation of actuation.  You can read the paper, or take a look at the slides posted here.

Mechanical energy can be converted to electrical energy by using a dielectric elastomer generator.  The elastomer is susceptible to various modes of failure, including electrical breakdown, electromechanical instability, loss of tension, and rupture by stretch.  The modes of failure define a cycle of maximal energy that can be converted.  This cycle is represented on planes of work-conjugate coordinates, and may be used to guide the design of practical cycles.

As a complement to the current issue of journal club, I would like to bring your attention to our current work on dielectric elastomers. 

Subject to a voltage, a dielectric elastomer can deform substantially, making it a desirable material for actuators. Designing such an actuator, however, has been challenging due to nonlinear equations of state, as well as multiple modes of failure, parameters of design, and measures of performance. This paper explores these issues, using a spring-roll actuator as an example.

Rob Wood teaches a course on micro/nano robotics, and asks me to give a 30-minute tutorial on the theory of dielectric elastomer actuators (DEAs).  I attach my slides, which might be useful to you if you'd like to include this topic in your class.  The tutorial draws upon work in the literature, as well as recent work in my group:

When an electric voltage is applied across the thickness of a thin layer of an dielectric elastomer, the layer reduces its thickness and expands its area. This electrically induced deformation can be rapid and large, and is potentially useful as soft actuators in diverse technologies. Recent experimental and theoretical studies have shown that, when the voltage exceeds some critical value, the homogenous deformation of the layer becomes unstable, and the layer deforms into a mixture of thin and thick regions.