The sand-grain-sized robots work cooperatively, similar to ants Jeong Jae Wie et al. Swarms of tiny robots guided by magnetic fields can coordinate to act like ants, from packing together to form a floating raft to lifting objects hundreds of times their weight. About the size of a grain of sand, the microrobots could someday do jobs larger bots cannot, such as unblocking blood vessels and delivering drugs to specific locations inside the human body. Jeong Jae Wie at Hanyang University in South Korea and his colleagues made the tiny, cube-shaped robots using a mould and epoxy resin embedded with magnetic alloy. These small magnetic particles enable the microrobots to be “programmed” to form various configurations after being exposed to strong magnetic fields from certain angles. The bots can then be controlled by external magnetic fields to perform spins or other motions. This approach allowed the team to “efficiently and quickly produce hundreds to thousands of microrobots”, each with a magnetic profile designed for specific missions, says Wie. The researchers directed the microrobot swarms to cooperatively …