Dynamic Modeling of Magnetic Helical Microrobots

Magnetic helical microrobots that can be driven by low-strength rotating magnetic fields have found wide applications, particularly in biomedical research. The motion dynamics of magnetic helical microrobots is critical for their intelligent control and for performing different tasks in complex environments. These microrobots convert rotational motion into translational motion along their central axis. Many factors contribute to their swimming dynamics, such as the geometry of the helix, the thickness and properties of the coated magnetic layer, the viscosity of the fluid, and the wettability of the helix in the fluid. In this paper, we establish a comprehensive dynamic model to analyze the swimming properties of magnetic helical microrobots at low Reynolds numbers. The influence of different designs of magnetic helical microrobots on their swimming velocity, step-out frequency, and maximum velocity is comprehensively analyzed, for the first time, providing valuable guidance for the design of helical microrobots for different applications. Our results are supported by a number of experimental studies.