Automated Manipulation of Microswarms Without Real-Time Image Feedback Using Magnetic Tweezers
Liushuai Zheng, Haibo Ji, Dong Sun
Abstract
Microswarms assembled by microparticles have shown promising prospects in targeted delivery. However, the automated manipulation of microswarms remains a considerable challenge due to the limitations of existing <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">in vivo</i> imaging technology. In this article, we design a magnetic tweezer system with a large workspace of 100 mm × 100 mm × 30 mm, which can assemble, transport, and disassemble microswarms efficiently. The magnetic tweezers generate rotating magnetic fields in the workspace, enabling magnetized microparticles to roll toward a specific point along spiral trajectories. The assembly process and mechanism of microswarms are analyzed. The developed system can assemble low-density magnetic microparticles to form a stable and compact microswarm at a predetermined position. Actuation of the magnetic tweezers allows precise navigation of the swarm without relying on real-time image feedback. The experimental results show that the flexible microswarm can achieve satisfactory motion performance and transmission efficiency. The microswarm can successfully move on a slope with an inclination angle of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$40^\circ $</tex-math></inline-formula> and navigate analog channels. The overall delivery efficiency can reach 92%.