Programmable Generation and Motion Control of a Snakelike Magnetic Microrobot Swarm

A new method for programmable generation and motion control of a snakelike magnetic microrobot swarm (SMS) is presented. The SMS is assembled from peanut-shaped hematite colloidal particles (length: ~3 μm, diameter: ~1.5 μm) driven by rotating magnetic fields. The SMS exhibits a dynamic-equilibrium chain that can capture additional microrobots to complete its evolution. Here, the SMS's mechanisms of generation and collective motion are analyzed and simulated. Based on an investigation of the magnetic attractive potential, hydrodynamic interactions, and viscous resistance, numerical models are proposed to estimate the interactive forces between the individual entities. Under microscopic visual navigation, efficient swarm generation is achieved using the Genetic algorithm, and robust target tracking is achieved using the Meanshift algorithm. Moreover, the reversible assembly and disassembly capabilities of the SMS are demonstrated. By regulating the rotational frequency, intensity, and steering angle of the input magnetic field, the SMS enables highprecision trajectory tracking at a desired velocity, in both simple and complex environments. Finally, it was verified that the SMS can perform serpentine locomotion in curved and branched narrow channels with high mobility. The established microrobotic swarm has great potential for efficient drug delivery in confined environments.