Hydrostatically coupled dielectric elastomer actuators

Within the emerging field of polymer-based mechatronics, soft materials showing intrinsic electromechanical transduction properties are being largely studied to develop new types of actuators. Among them, so-called dielectric elastomer (DE) actuators are one of the most promising. This paper presents a new class of such devices, which uses an incompressible fluid to mechanically couple an active part to a passive part. The active part is elastic and works according to the DE actuation principle, while the passive part represents the end-effector, in contact with the load. The fluid is distributed between the active and passive parts, remaining entirely internal to the overall actuator; accordingly, the fluid transmits the actuation hydrostatically from the active to the passive part and, then, to the load. This concept leads to a new family of versatile DE actuators, characterized by less stringent design constraints for shape, size, and spatial arrangement of subparts of the device, along with adequate electrical safety. The paper describes these and additional benefits, showing how different uses of the proposed concept can result in actuators with different architectures and capabilities, suitable for diverse needs.