Electroactive actuators (cardiac assist device)

The invention relates to actuators based on electroactive polymeric materials for use in pumping fluids or in other applications where a contractile actuation is required, in particular, although not necessarily exclusively, for use in vascular pulsation devices such as a variable aortic tension device. Embodiments disclosed include an actuator comprising: an inner tubular structure; an outer tubular structure surrounding the inner tubular structure and comprising a plurality of layers of a dielectric elastomeric material and a tubular elastic support structure, the elastic support structure configured to maintain a pre-stress in the layers of the dielectric elastomeric material, wherein the outer tubular structure is configured to contract in a radial direction around the inner tubular structure upon application of an actuation voltage signal across the dielectric elastomeric material layers