Magnetically Actuated Multiscale Medical Robots

Magnetic manipulation systems designed to date have typically relied on either stationary electromagnetswhich facilitate straightforward real-time control, but result in large and complex systemsor slowly moving permanent magnetswhich generate strong fields, but are typically controlled in a quasistatic fashion. In the Telerobotics Lab at the University of Utah, we are exploring the use of small permanent magnets, controlled in a dynamic fashion, for the control of in vivo medical devices. By understanding the nonuniform dipole field generated by a permanent magnet, and by capitalizing on the structure provided by a given medical procedure, we can exploit a single dynamically controlled permanent magnet for a variety of applications. We find that unintuitive phenomena occur in this dynamic control regime, and these phenomena can be exploited for improved actuation and safety. I will present our recent results for the control of magnetic capsule endoscopes, which generalize to other swimming and crawling devices that utilize rotating magnetic fields for propulsion, as well as our recent results for magnetic cochlear implants, which generalize to other magnetically tipped compliant devices such as magnetic catheters. Because our methods capitalize on the analytical point-dipole model, we have also worked to characterize the accuracy of that model, and to determine what permanent-magnet geometries result in a field that is most accurately modeled by a point-dipole model.