Formation and Actuation of Micro/Nanorobot Swarms in Bio-Fluids

Micro/nanorobot swarms are a promising medical tool for applications such as in vivo targeted drug delivery. Bio-fluids with complex composition have non-negligible effects on formation and locomotion of microswarms. This chapter begins by reviewing three types of magnetic micro/nanorobot swarms, namely medium-induced, magnetic field-induced, and weakly interacted swarms. The effects of bio-fluid properties (including viscosity, ionic strength, and mesh-like structure) on vortex-like microswarms (medium-induced) and ribbon-like microswarms (magnetic field-induced) are investigated, and the selection strategy for optimized swarms in bio-fluids is proposed. The selection strategy is validated in gastric acid, blood plasma, whole blood, fetal bovine serum, hyaluronic acid, and bovine vitreous humor. Finally, the controlled navigation of microswarms in bio-fluids (e.g., whole blood and vitreous humor) and in an ex vivo bovine eyeball is presented.