Multimodal magnetic miniature robot for adaptive navigation in amphibious environments

Magnetic miniature robots hold great potential for minimally invasive biomedical applications due to their small size and biocompatibility. However, single-modal robots face challenges in complex environments, while existing multimodal robots that rely on elastic materials lack kinematic stability and are sensitive to environmental factors. This work introduces a novel Multimodal Magnetic Miniature Robot (MMMR) which combines helical swimming with bipedal walking. The MMMR can adaptively navigate in diverse amphibious environments, including open liquids, shallow liquids, liquid surfaces, and solid surfaces. Owing to the structure-driven locomotion mechanism, the MMMR exhibits excellent kinematic stability. The helical swimming is optimized through simulations and enhanced with a closed-loop control system for height and directional correction. Bipedal walking is designed for adaptive locomotion on liquid and non-liquid surfaces. Experiments confirmed precise multimodal control, including swimming, walking to targets, and retrieval, offering a novel solution for miniature robots in diverse environments.