A Novel Multiple-Shot Milli-Scale Magnetic Robot for Cargo Delivery

Magnetic actuation allows distant and safe actuation of small-scale untethered robots. This class of robots is particularly appealing for targeted delivery and on demand release of therapeutic cargo. Most state-of-the-art systems focused so far either on single-shot release or leveraged battery-driven actuation for delivering multiple therapeutic agents’ doses. In this work, we propose a novel magnetic milli-scale carrier design that can be distantly navigated and triggered to release 2 or 4 cargo shots, on demand. The carrier features a modular design with a permanent magnet in each compartment. Robot realizations with 1 and 2 compartments are analyzed in this paper. A straightforward control strategy relies on tuning direction and intensity of applied magnetic fields for robot navigation and cargo delivery. Experiments were performed in an aqueous environment to validate carrier locomotion and controlled release capabilities. The prototyped carriers have a parallelepiped shape (12x2x10 mm and 12x6x10 mm for one and two compartments, respectively) and can be wirelessly navigated by an external magnet at a distance larger than 100 mm within 5 mm deviation from the desired trajectory. Upon docking, release can be triggered by modulating the external magnetic field. Quantitative metrics revealed consistent release dosage between prototypes and among different cargo compartments.