Scientists in South Korea have developed a swarm of tiny magnetic robots that work together like ants to accomplish incredible feats, including traversing and picking up objects several times their size.
The findings were published Wednesday, December 18, in the journal Cell Press. deviceThis suggests that swarms of these microrobots operating under rotating magnetic fields could be used to perform difficult tasks in challenging environments that individual robots would struggle to handle, such as providing minimally invasive treatment for blocked arteries and precise guidance of organisms.
“The high adaptability of the microrobot swarm to the surrounding environment and the high level of autonomy in swarm control were surprising,” said lead author Jung Jae Wie of the Department of Organic and Nanotechnology Engineering at Hanyang University in Seoul, South Korea.
Wie and colleagues tested how well a swarm of microrobots performed in different assembly configurations performing a variety of tasks. They found that swarms assembled at high aspect ratios can climb obstacles five times higher than the body length of a single microrobot and hurl themselves over the obstacles one by one.
A large swarm of 1,000 microrobots with high packing density formed a floating raft on the water and wrapped themselves around a pill 2,000 times heavier than the weight of each robot, allowing the swarm to transport the drug through the liquid.
On dry land, a swarm of robots succeeded in carrying a load 350 times heavier than an individual, and another swarm of microrobots was able to unclog a vascular tube similar to a clogged blood vessel. Finally, through rotation and orbital dragging motions, Wie’s team developed a system that allows a swarm of robots to guide the movements of small organisms.
Scientists have become increasingly interested in studying how swarms of robots can collectively achieve goals, inspired by the way ants band together into rafts to fill gaps in their paths or survive floods. Likewise, working together makes the robots more resistant to failure. Even if some members of the group fall short of their goals, the remaining members will continue to perform their programmed behaviors until they eventually succeed.
“Previous swarm robotics research has focused on spherical robots that come together through point-to-point contact,” says Wie. In this study, the researchers designed a swarm of cube-shaped microrobots that share stronger magnetic forces.
This is attractive because a larger surface area (the entire face of each cube) can be contacted.
Each microrobot is 600 micrometers tall and consists of an epoxy body embedded with ferromagnetic neodymium-iron-boron (NdFeB) particles, allowing it to respond to magnetic fields and interact with other microrobots. A swarm of robots can self-assemble by powering the robots with a magnetic field created by rotating two connected magnets. The researchers programmed the robots to come together in different configurations by changing the angle at which they were magnetized.
“We developed a cost-effective mass production method using in-situ replica molding and magnetization to ensure uniform geometry and magnetization profile for consistent performance,” Wie said.
“The research results are promising, but a higher level of autonomy is needed to prepare the swarms for real-world applications,” says Wie.
“Swarms of magnetic microrobots require external magnetic control and lack the ability to autonomously navigate complex or confined spaces like a real artery,” he says. “Future research will focus on improving the level of autonomy of microrobot swarms, such as real-time feedback control of their movements and trajectories.”
