Folded dielectric elastomer actuators

Polymer-based linear actuators with contractile ability are currently demanded for several types of applications. Within the class of dielectric elastomer actuators, two basic configurations are today available for such a purpose: the multi-layer stack and the helical structure. The first consists of several layers of elementary planar actuators stacked in mechanical series and electrical parallel. The second configuration relies on a couple of helical compliant electrodes alternated to a couple of helical dielectrics. The fabrication of both these configurations presents today some specific drawbacks, arising from the peculiarity of each structure. Accordingly, the availability of simpler solutions may boost the short-term use of contractile actuators in practical applications. For this purpose, a new configuration is here described. It consists of a monolithic structure made of an electroded sheet, which is folded up and compacted. The resulting device is functionally equivalent to a multi-layer stack with interdigited electrodes. However, with respect to a stack the new configuration is advantageously not discontinuous and can be manufactured in one single phase, avoiding layer-by-layer multi-step procedures. The development and preliminary testing of prototype samples of this new actuator made of a silicone elastomer are here presented.