Bio-inspired magnetic soft robot with dual-modal locomotion for enhanced liquid–air interface navigation

Small-scale magnetic soft robots are promising candidates for minimally invasive medical applications; however, they struggle to achieve efficient locomotion across various interfaces. In this study, we propose a magnetic soft robot that integrates two distinct bio-inspired locomotion modes for enhanced interface navigation. Inspired by water striders’ superhydrophobic legs and the meniscus climbing behavior of Pyrrhalta nymphaeae larvae, we developed a rectangular sheet-based robot with hydrophobic surface treatment and novel control strategies. The proposed robot implements two locomotion modes: a bipedal peristaltic locomotion mode (BPLM) and a single-region contact-vibration locomotion mode (SCLM). The BPLM achieves stable movement at 20 mm/s through coordinated front–rear contact points, whereas the SCLM reaches an ultrafast speed of 52 mm/s by optimizing surface tension interactions. The proposed robot demonstrates precise trajectory control with minimal deviations and successfully navigates confined spaces while manipulating objects. Theoretical analysis and experimental validation demonstrate that the integration of triangular wave control signals and steady-state components enables smooth transitions between locomotion modes. This study presents a new paradigm for bio-inspired design of small-scale robots and demonstrates the potential for medical applications requiring precise navigation across multiple terrains.