Polyelectrolyte Materials for Dielectric Elastomer Energy Harvesting
Abstract
Dielectric elastomers actuators are compliant capacitors which can convert electrical
energy into mechanical energy [1]. The simplest device consists of a thin elastomer sheet
sandwiched between two compliant electrodes. In actuation mode, a voltage is applied to the
electrodes and the attractive Coulombic force between the opposing charges squeezes the
elastomer causing it to expand perpendicular to the applied electric field. Since they are
electrically driven, the response speed of DEAs is usually limited by the viscoelastic response of
the constituent polymer.
In terms of ease of delivering power, as well as response speed, DEAs are some of the
most promising technologies for the emerging field of soft robotics [2]. However, existing DEA
technologies are severely limited in three key areas. First, most elastomers require some
amount of mechanical pre-strain in order to achieve large deformation. Typically the strain is
maintained by application of a rigid frame that improves the performance of the elastomer, but
negates most of the benefits associated with a soft, compliant actuator. Second, the fields
required for actuation are high, in the 20-200 V/micron range, causing the actuation voltage to
be relatively high (3 - 20 kV). While the DEAs themselves require low power inputs, the high
voltage requirement greatly limits where DEAs can be used and how portable they can be, since
high voltage power supplies are generally bulky and heavy. Third, since DEAs are compliant
capacitors, the strain in the electrodes has to match the strain in the elastomer. There are
extremely few materials which can conduct electricity, bond well to an elastomer,