Applications for solid state electrically activated actuators with large strains include: micro-robotics, haptics-tactile interfaces, electronics-camera auto-focus mechanisms, micro and nano positioning, fuel injector actuation.
Previous actuators such as shape memory metals or piezoelectrics do not provide large mechanical displacements via direct electrical activation. This invention creates the possibility to actuate a phase transformation with a large mechanical displacement using an electric field.
This technology is based on the principle that for any phase transformation to occur there must exist a difference in an extensive variable between the two phases. These materials (e.g. ceria-doped zirconia) exhibit a change polarization between phases, which has not been demonstrated before. This allows the material to produce a mechanical displacement when subject to an electric field. The simplest implementation of this type of actuator would resemble a parallel plate capacitor with a layer of active ceramic material between to conductive electrodes. Then a voltage could be applied across the material which would induce an electric field and cause the material to actuate.
Actuation due to an electric field
Improved cyclic properties