Pivotal Role of Nanoparticle Distribution on Agile Steering of Magnetic Microrobots

Magnetic microrobots can be spatiotemporally steered by manipulating external magnetic fields, achieving rapid locomotion. However, for high-speed magnetic microrobots, steering stability is crucial to control actuation speeds along predetermined trajectories. Herein, we discover that nanoscale distribution of magnetic nanoparticles is key to ensuring the steering stability of agile magnetic microrobots. A model system comprising two different processing methods is implemented to induce either macroscopic phase separation or nanoscale distribution of nanoparticles within thermoplastic nanocomposites-based magnetic microrobots. The dispersive and distributive mixing of magnetic nanoparticles is evaluated via systematic investigation on magnetic, thermal, and rheological properties. According to the spatial distribution states of the magnetic nanoparticles, magnetic microrobots exhibit stark differences in motion uniformity and trajectory regularity during agile pivoting motion. Our findings elucidate the correlations among nanocomposite processing, nanoparticle distribution, physical properties, and magnetic actuation, providing valuable insights for designing stimuli-responsive miniaturized robots with enhanced locomotion control.