Magnetic Microrobotic Swarms in Fluid Suspensions

Abstract Purpose of Review Microrobotic swarms have attracted extensive attentions due to their potential in medical and bioengineering applications. Because of the small sizes of swarm agents, integrating actuators, sensors, and control circuits are difficult. Microrobotic swarms in different fluid environments should be actuated and navigated by external physical fields, chemical fuels, and biological power. Magnetic fields have advantages, including real-time control, programmability, and high penetrability, and thus they are widely used to actuate magnetic microrobotic swarms. This review summarizes the recent remarkable progress in the magnetic actuation and navigation of magnetic microrobotic swarms. Recent Findings After development and evolution, the design of magnetic agents, and techniques of magnetic actuation and automatic control are now in place. Magnetic microrobotic swarms formed by different agents have been proposed, such as nanoparticles, artificial bacterial flagella, and bacteria. By tuning the applied fields, the morphology, orientation, and position of swarms can be adjusted on demand. Reconfigurability and motion dexterity are endowed to the microrobotic swarms. Summary The wireless magnetic actuation systems for microrobotic swarms are introduced, and the characteristics of microrobotic swarms actuated by different customized magnetic fields are described, such as rotating, oscillating, and hybrid fields. The results show that the swarm intelligence has been enhanced. Finally, the current challenges and opportunities in this field are discussed. The developments in materials, actuation methods, control strategies, and imaging modalities will transform the magnetic microrobotic swarms from lab to practical clinic.