Field-focused reconfigurable magnetic metamaterial for wireless power transfer and propulsion of an untethered microrobot

Abstract Magnetic metamaterials have great potential for various future research and commercial applications. In this work, we investigate field-focused magnetic metamaterial for wireless power transfer (WPT) and propulsion of an untethered microrobot. With small dimensions, the operating time of an untethered microrobot is limited by the battery capacity. To perform critical missions for a long time, realizing stable power for the microrobot is a major challenge. We propose a new method of generating both wireless power and propulsion for a tiny untethered microrobot. The method is realized using the cavity mode created on a dynamically reconfigurable metasurface. The cavity effectively enhances the efficiency of the WPT by focusing the fields into the small regions where the receiver is located. Instead of a time-varying magnetic field, which requires shielding to generate a net force, we use a static field for propulsion. We propose a simple method to break the symmetry needed for generating a net force. Experiments are performed using a prototype microrobot having a size of 4 cm × 4 cm and a weight of 5.5 g floating on a water surface. The proposed approach achieves a velocity of 0.85 mm/s under a magnetic field of 0.815 mT and an input power of 1 W. Using the propulsion control, we demonstrate a microrobot navigating to multiple goal locations.