In complex systems like aircraft engines and oil refinery machines, pipeline inspection is an essential task for ensuring safety. Here, we proposed a type of smart material–driven pipeline inspection robot (weight, 2.2 grams; length, 47 millimeters; diameter, <10 millimeters) that could fit into pipes with sub-centimeter diameters and different curvatures. We adopted high–power density, long-life dielectric elastomer actuators as artificial muscles and smart composite microstructure–based, high-efficiency anchoring units as transmissions. Fast assembling of components using magnets with an adjustable number of units was used to fit varying pipeline geometries. We analyzed the dynamic characteristics of the robots by considering soft material’s unique properties like viscoelasticity and dynamic vibrations and tuned the activation voltage’s frequency and phase accordingly. Powered by tethered cables from outside the pipe, our peristaltic pipeline robot achieved rapid motions horizontally and vertically (horizontal: 1.19 body lengths per second, vertical: 1.08 body lengths per second) in a subcentimeter-sized pipe (diameter, 9.8 millimeters). Besides, it was capable of moving in pipes with varying geometries (diameter-changing pipe, L-shaped pipe, S-shaped pipe, or spiral-shaped pipe), filled media (air or oil), and materials (glass, metal, or carbon fiber). To demonstrate its capability for pipeline inspection, we installed a miniature camera on its front and controlled the robot manually from outside. The robot successfully finished an inspection task at different speeds.

Dielectric elastomer actuators (DEAs) as a typical class of electroactive polymers have been developed rapidly in the last two decades due to their advantages such as large strain, high energy density, and fast response. The high‐frequency characteristics of DEAs enable them to be applied in a wider range of fields. In this review, the high‐frequency (>10 Hz) characteristics and applications of DEAs are focused on. The basic concepts and metrics for high‐frequency DEAs are first given. Next, the commercial and synthesized dielectric and electrode materials of DEAs used in high‐frequency applications are reviewed. Following materials, strategies for extending the lifetime of DEAs are introduced. Subsequently, the dynamic modeling approaches for DEAs are presented, considering damping, inertia, and the electrical loss. Building on the fundamental research, some important applications are summarized based on the high‐frequency motions of DEAs including loudspeakers, active vibration suppression, pumps/valves, haptic devices, and high‐speed mobile robots. Finally, the conclusions and future perspectives are given. This review will give readers a clearer understanding of how to design and use high‐frequency DEAs.