Prestressed Thin-Plate Actuators for Enhancing Performance of Pneumatic Soft Robots

With the rapid development of soft robotics, there is a growing demand for compact, high-performance, and flexible actuators. Pneumatic actuators are particularly favored by researchers due to their high efficiency, low cost, and ease of fabrication. However, the existing pneumatic actuators are faced with challenges such as large volume, low actuating frequency, and insufficient propulsion. For the first time, this work presents a novel thin-plate pneumatic actuator based on prestressed principles, featuring an efficient energy storage and release mechanism. The actuator consists of a prestretched layer, a constrained layer, and a chamber (PCC), with a total thickness of less than 1 mm. Therefore, the elastic potential energy is preserved in the prestretched film within the actuator body, which enables high actuating frequency and large propulsion. Effects of key structural parameters on the propulsion of the PCC actuator are investigated by a mathematical model, finite element analysis, and experiments to further elucidate its energy storage and release mechanism. Moreover, the PCC actuator is applied to realize a soft gripper, a prestressed hinge, and a wireless jellyfish-like robot, whose performances are verified by experiments. Results demonstrate the high flexibility and rapid response of the soft gripper and prestressed hinge. In particular, the gripper is capable of stably gripping objects 40 times its weight for extended periods. In addition, the wireless jellyfish-like robot achieves an upward swimming speed of 58.03 mm/s, which is superior to the existing soft jellyfish-like robots of similar size. Overall, the PCC actuator features a lightweight structure and high energy storage capacity, providing significant potential for innovative applications in soft robotics.