Polymer Power: Dielectric Elastomers and Their Applications in Distributed Actuation and Power Generation

In the past decade, dielectric elastomers have emerged as promising multifunctional smart energy-transduction materials in several actuation, sensing, and electric power generation applications. As actuators, dielectric elastomers have demonstrated strains (over 300%) and specific energy density (over 3.4 J/g) larger than that observed in any other field-activated smart material. In generator mode, dielectric elastomers have been shown to generate electricity from mechanical motion with high specific energy densities (0.4 J/g) and predicted high efficiencies (80–90%). In addition to superior performance, dielectric elastomers have two features that distinguish them from other energytransduction materials: They are made from low cost materials that can be easily fabricated in large-area sheets and they are very compliant. This allows good impedance matching where strain in the material result from human body motion, combustion, or from wind or ocean waves. These characteristics suggest relevance to power generation in rural areas or other areas where there is not reliable central power. Two case studies—a shoe-based or “heel strike” generator and a polymer engine (in which an expanding polymer chamber replaces a conventional piston-cylinder arrangement)—are used to illustrate the promise of these materials for energy transduction.