Ultrafast, Programmable, and Electronics-Free Soft Robots Enabled by Snapping Metacaps

Soft robots offer a myriad of potential because of their intrinsically compliant bodies, enabling safe interactions with humans and adaptability to unpredictable environments. However, most of them have limited actuation speeds, require complex control systems, and lack sensing capabilities. To address these challenges, herein, a class of metacaps is geometrically designed by introducing an array of ribs to a spherical cap with programmable bistabilities and snapping behaviors, enabling several unprecedented soft robotic functionalities. Specifically, a centimeter-sized, sensor-less metacap gripper is demonstrated that can grasp objects in 3.75 ms upon physical contact or pneumatic actuation with tunable behaviors that have little dependence on the rate of input. The grippers can be readily integrated into a robotic platform for practical applications. The metacap can further enable propelling of a swimming robot, exhibiting amplified swimming speed as well as untethered, electronics-free swimming with tunable speeds using an oscillating valve. The metacap designs provide new strategies to enable the next-generation soft robots to achieve high transient output energy and autonomous and electronics-free maneuvering. © 2023 The Authors.