Generating two independent rotating magnetic fields with a single magnetic dipole for the propulsion of untethered magnetic devices

Untethered magnetic devices (UMDs) driven by rotating magnetic fields have been proposed for applications in minimally invasive medicine. Previous work has explored the propulsion and guidance of a single UMD using a rotating magnet dipole source, and actuation of multiple UMDs has focused on the use of uniform magnetic fields. This work seeks to extend the methods for remote actuation using a single magnet dipole source to generate two rotating magnetic fields with arbitrary independent rotation axes at any two points with a common rotation frequency. The solutions found show that there are multiple positions and rotation axes of the magnet dipole that can generate these rotating fields. The method is demonstrated with two screw-type UMDs propelled independently within an agar gel block using a single permanent-magnet actuator.