Freeform liquid 3D printing of hydraulically enhanced dielectric actuators

Progress towards autonomous high-performance soft and hybrid robotic devices relies on the engineering of advanced actuators with fast response, compliance, low-power consumption, and high stress or strain changes. Dielectric elastomers have emerged as a promising option due to their fast, reversible, and electrically controlled actuation. However, current fabrication processes constrain geometries, and limit both miniaturization and achievable strains. Here, we propose an original and simple fabrication process based on an emerging additive manufacturing technology, called freeform liquid 3D printing. By transforming a dielectric liquid into a dielectric yield stress gel suitable to be used as support bath, silicone-based hydraulically enhanced dielectric actuators could be 3D printed, allowing for both miniaturization and enhanced geometrical freedom. A single unit at ∼ 10 mm length-scale, four to five times smaller than existing actuators, could be fabricated and demonstrated a linear expansion up to 6 %, comparable to existing actuators. Our result demonstrates the possibility to engineer complex dielectric actuators with higher performances in an integrated manner. The design freedom afforded by additive manufacturing can lead to interesting functional applications in soft robotics and hybrid devices. © 2022