Magnetic Microlassos for Reversible Cargo Capture, Transport, and Release

Most microbot propulsion schemes powered by external fields or chemical reaction lack the capability to load and unload contents as may be necessary for applications such as drug delivery. To address this shortcoming, we introduce a reversible method that employs flexible and linked superparamagnetic chains that form closed rings or “lassos” in the presence of a planar rotating magnetic field. We show that these magnetic lassos can roll at substantial velocities with precise spatial control by manipulating both field strength and phase lag. These rings can be used to grab onto cargo then translate based on a wheel-type mechanism, all without the need for chemical attachment or disengagement. In addition, we demonstrate that once the target destination is reached, cargo can be easily released upon field removal leaving the lasso ready for reuse.