With a swipe of a magnet, microscopic 'magno-bots' perform complex maneuvers

Under a microscope, a bouquet of lollipop-like structures, each smaller than a grain of sand, waves gently in a Petri dish of liquid. Suddenly, they snap together, like the jaws of a Venus flytrap, as a scientist waves a small magnet over the dish. What was previously an assemblage of tiny passive structures has transformed instantly into an active robotic gripper. The lollipop gripper is one demonstration of a new type of soft magnetic hydrogel developed by engineers at MIT and their collaborators at EPFL and the University of Cincinnati.