  Magnetic microrobots have been developed for navigating microscale
environments by means of remote magnetic fields. However, limited propulsion
speeds at small scales remain an issue in the maneuverability of these devices
as magnetic force and torque are proportional to their magnetic volume. Here,
we propose a microrobotic superstructure, which, as analogous to a
supramolecular system, consists of two or more microrobotic units that are
interconnected and organized through a physical (transient) component (a
polymeric frame or a thread). Our superstructures consist of microfabricated
magnetic helical micromachines interlocked by a magnetic gelatin nanocomposite
containing iron oxide nanoparticles (IONPs). While the microhelices enable the
motion of the superstructure, the IONPs serve as heating transducers for
dissolving the gelatin chassis via magnetic hyperthermia. In a practical
demonstration, we showcase the superstructure's motion with a gradient magnetic
field in a large channel, the disassembly of the superstructure and release of
the helical micromachines by a high-frequency alternating magnetic field, and
the corkscrew locomotion of the released helices through a small channel via a
rotating magnetic field. This adaptable microrobotic superstructure reacts to
different magnetic inputs, which could be used to perform complex delivery
procedures within intricate regions of the human body.
