Multimodal Locomotion of Amphibious Soft Microrobots for Multi-Environment Exploration

Amphibious robots have immense potential for exploration in complex environments, but rigid and intricate structures limit adaptability and may cause mechanical disruption or ecological damage. This study presents a novel amphibious soft microrobot capable of seamlessly transitioning between land and water locomotion. We leverage the high power density and reversible actuation of 4D-printed liquid crystal elastomers (LCEs) combined with flexible heating circuits to fabricate LCE amphibious actuators. These actuators enable large deformation, providing sufficient power for locomotion on both land and water. To enable controllable swimming, we design a buoyancy-regulating module inspired by the swim bladder of fish. This module consists of a liquid-filled elastomer integrated with flexible heating circuits, allowing dynamic tuning of the robot's buoyancy for stable underwater propulsion. We systematically characterize the robot's amphibious and multidirectional locomotion, demonstrating its ability to hover at different depths, swim in multiple directions, cross obstacles, and navigate narrow gaps. The proposed design offers a simple yet highly deformable structure, enabling seamless transitions between crawling and swimming, paving the way for advanced applications in environmental monitoring and exploration.