A Soft Reprogrammable Permanent Magnet for Magnetic Soft Robots

Magnetic soft robots promise unprecedented medical applications due to their untethered motion and control capabilities. These magnetic soft robots, which are navigated by external magnetic sources, can be designed to change their shape or mechanical properties under magnetic fields. However, keeping the modified state constant often requires a continuous power supply with high energy consumption. Changing the magnetic properties of soft magnetic robots can overcome this energy demand. To this end, we present a novel soft and reprogrammable permanent magnet whose magnetization can be remotely switched on and off by a short-duration, low- energy external magnetic pulse. It is suitable for on-board use in magnetic soft robots, either to modify the magnetic properties of such robots or to actuate certain functionalities. Based on this concept, two untethered millimeter-scale magnetic soft robots are developed for applications in capsule endoscopy and medical grasping. The predominant feature of the proposed robots is that, apart from navigation, only state change requires an external power supply, and state retention is enabled by the onboard reprogrammable permanent magnet. The proposed novel magnet allows soft magnetic robots to perform specific tasks without physical tethering by enabling remote state change. The presented concept opens new opportunities for magnetic soft robots to achieve energy-efficient, untethered operation with remotely programmable states, offering significant potential for advanced biomedical applications.