Tiny robot swarms that deliver drugs and help perform operations inside the body have long been a dream of scientists and science-fiction writers alike. But the prototypes we have are rigid and often slow to respond to their wireless commands. Now, researchers have developed millimeter-long robots that can fold into countless different shapes—allowing these micromachines to do things like grasp and crawl—using magnets as remote controls.
Previous magnetically controlled minions were stiff because of the magnetic materials used to build them. To create a flexible robot, researchers embedded particles of the magnetic element neodymium in more pliable materials like plastics. The researchers used a pair of powerful magnets to flip the polarity of the neodymium in select sections of the robot, allowing them to repel and attract its different parts with a magnetic field. Then, they shined ultraviolet light on the segments, curing the material they were embedded in and locking them into place, they report today in Science Robotics. The researchers programmed bots capable of 3D movements like grasping, crawling, and swimming (above) by patterning the polarities of the different segments.
To assist with surgeries or deliver drugs inside the human body, future robots would need to ditch their toxic neodymium for less dangerous metals like iron. Such metals could still work, say researchers, but they may require stronger magnets to be manipulated. In addition to medical applications, the bots could also be used to staff miniaturized factories building even smaller goods.
Despite their sophistication, these wireless micromachines are cheap and easy enough to make that they could be thrown away after use—potentially expanding their utility in medicine where cleanliness is essential.