Vector-Controlled Wheel-Like Magnetic Swarms With Multimodal Locomotion and Reconfigurable Capabilities

Abstract

Inspired by the biological collective behaviors of nature, artificial microrobotic swarms have exhibited environmental adaptability and tasking capabilities for biomedicine and micromanipulation. Complex environments are extremely relevant to the applications of microswarms, which are expected to travel in blood vessels, reproductive and digestive tracts, and microfluidic chips. Here we present a strategy that reconfigures paramagnetic nanoparticles into a vector-controlled microswarm with 3D collective motions by programming sawtooth magnetic fields. Horizontal swarms can be manipulated to stand vertically and swim like a wheel by adjusting the direction of magnetic-field plane. Compared with horizontal swarms, vertical wheel-like swarms were evaluated to be of approximately 15-fold speed increase and enhanced maneuverability, which was exhibited by striding across complex 3D confinements. Based on analysis of collective behavior of magnetic particles in flow field using molecular dynamics methods, a rotary stepping mechanism was proposed to address the formation and locomotion mechanisms of wheel-like swarm. we present a strategy that actuates swarms to stand and hover in situ under a programming swing magnetic fields, which provides suitable solutions to travel across confined space with unexpected changes, such as stepped pipes. By biomimetic design from fin motion of fish, wheel-like swarms were endowed with multi-modal locomotion and load-carrying capabilities. This design of intelligent microswarms that adapt to complicated biological environments can promote the applications ranging from the construction of smart and multifunctional materials to biomedical engineering.

Design and Control of the Magnetically Actuated Micro/Nanorobot Swarm toward Biomedical Applications

“…[95] Zhang et al achieved the ability for wheel-like swarms to stand and hover in situ by programming oscillating magnetic fields, allowing the swarm to adapt to complex biological environments. [88] Apart from the single swarm mode manipulation, the regulation methods of using different types of magnetic fields to form multiple dynamic swarm modes have also been proposed. He et al presented a strategy to reconfigure hematite colloidal particles into liquid, chain, vortex, and ribbon-like microrobot swarms using alternating magnetic fields (Figure 4b).…”

“…The particles of two vortices began to exchange and enter the fusion, eventually forming a large stable circular vortex. [ 88 ]…”

Micro/Nanorobotic Swarms: From Fundamentals to Functionalities

“…In magnetic fields, magnetic agents interact with each other through dipole–dipole interactions and may assemble into chainlike clusters [Figure A­(i)]. By rotating or oscillating the magnetic fields, the chains perform rotation or oscillation and they may undergo fragmentation because of viscous torque. − The magnetic interaction between the chains changes with the time-varying fields, and compact swarms are generated when the overall magnetic interaction is attractive, e.g., wheel-like particles swarm in out-of-plane rotating fields. − The generation of a ribbonlike paramagnetic nanoparticle swarm by using an in-plane dual-axis oscillating magnetic field has been demonstrated (Figure B). , The particles initially formed oscillating chains. As the strength of the magnetic field changed with time, the chains broke because of viscous torque when the dipole–dipole interaction was weak, while they attracted each other to reform chains when the interaction was sufficiently strong.…”

Bioinspired self-assembled colloidal collectives drifting in three dimensions underwater

“…Existing strategies for driving the motion of colloidal collectives rely predominantly on physical boundaries, such as liquid-solid and liquid-air interfaces, to introduce spatially asymmetrical interactions (41)(42)(43)(44). Although collectives that depend on the substrate for movement can be maintained as a dynamically stable entity, they are poorly adapted to their environment, e.g., they are unable to detach from the substrate and cross-vertical obstacles that are several times larger than their size (23,43,(45)(46)(47). Therefore, this strong dependence on the presence of a border is a fundamental limitation that impairs colloidal collective maneuverability and their application scenarios.…”