Microrobot swarms mimic ant-like feats of strength

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 climb over obstacles five times higher than any single microrobot and form a floating raft on water. The bots also pushed through a clogged tube and transported a pill 2000 times their individual weight through liquid, demonstrating potential medical applications.

“These magnetic microrobots hold great promise for minimally invasive drug delivery in small, enclosed and confined spaces,” says Xiaoguang Dong at Vanderbilt University in Tennessee, who was not involved in the research. But the microrobots cannot yet autonomously navigate complex and tight spaces such as arteries.

Dong says there are safety challenges too, including needing to coat the “potentially toxic” magnetic particles with human-friendly materials. Still, he says he is optimistic about the future medical uses of such microrobots. If safe, the bots “can effectively navigate to targeted disease sites and deliver drugs locally”, making treatments more precise and effective.