Reprogrammable Soft Robot Actuation by Synergistic Magnetic and Light Fields

Soft robots controlled by different actuation schemes are flourishing owing to the continued development of smart materials. However, most of the existing actuators are powered by a single source with predetermined mechanical properties and motion characteristics. Speed, power, and efficiency of these actuators are thus far inferior to their conventional counter parts. How to preload or alter the internal energy distribution and trigger rapid kinetic energy release combined with re-programmability is a challenge and corresponding solutions will extend the practical use of soft robotics. Herein, a hybrid magnetically and photothermally responsive actuator with high degrees of freedom by using a coupled-field manipulation strategy is proposed. As a proof-of-concept, a crab robot (CraBot) that contains uniformly distributed superparamagnetic particles and localized light-responsive joints is produced. The spatial magnetic field exerts force on the robot, leading to real-time adjustment of energy distribution within the entire robot. Meanwhile, the focused light field enables selective deformation of specific joints, releasing the accumulated energy into kinetic energy of motion for quick actuation. The directional accumulation and addressable release of elastic energy enables the CraBot to walk efficiently with improved power and speed. Such a hybrid-field manipulation strategy holds great promise for sophisticated actuation of soft robots.