A Modular Magnetic Navigation System for Actuating Surface Microwalkers

The complex motion modes of surface microwalkers rely on magnetic torque generated by rotating/oscillating magnetic fields. Actuation systems based on rotating permanent magnets exhibit considerable advantages in generating these dynamic fields due to their high flexibility. However, current omnidirectional magnet control systems are complex in design, while single-axis rotational control systems are limited to specific motion modes. This study presents a modular magnetic navigation system based on the quasi-omnidirectional magnet control, aiming to balance control complexity and system functionality. This system utilizes a dual-sided layout, with the rotating magnet system and imaging system positioned on opposite sides of the sample module, thereby reducing control complexity for target tracking in a dynamic field of view. The dual-axis rotation control of the magnet is achieved by a decoupled two-degree-of-freedom rotating platform, enabling the switching of multiple rotation fields. Various rotating magnetic fields generated by the proposed system are modeled, and different motion modes of surface microwalkers driven by the system are analyzed. Based on this, corresponding motion control strategies are provided for different motion modes. Finally, experiments are performed to verify the performance of the proposed system in actuating both rolling and swarm motion of surface microwalkers. The results demonstrate that the proposed modular navigation system has comparable actuation capabilities to existing systems, but with lower control complexity, suggesting its potential for designing magnetic actuation systems in clinical applications