Vortex control and micro-object cluster transport by collective high-speed swimming magnetic robots

Hanyang University announced on November 11 that a team of Professor Wie Jung-jae of Hanyang University's Department of Organic and Nano Engineering has developed a technology that can collect thousands of floating micro plastics through collective behavior control of magnetic robots.

Collective behavior is a common phenomenon in groups of ants, fish, and birds in the natural world. By doing this, many creatures can cooperate to move food or defend themselves against predators. Leveraging the collective behavior of multiple objects in robotics can complete tasks that are difficult to perform with a single object, as well as effectively perform time-consuming tasks.

Professor Wie's team used a robot's collective behavior strategy to quickly transport a large number of micro-objects. A gripper-type robot picks up objects one by one, transfers them to the desired position, and puts them down. Though it can have delicate motion control, it is hard to move thousands of objects. Instead of a gripper robot, Professor Wie's team developed a magnetic robot capable of high-speed swimming. When a planar rotating magnetic field was applied under the board on which the robot was located, the magnetic robot group was rotated at a high speed on the water. As a result, they have implemented a technology that can create a vortex on the surface of the water and capture thousands of floating micro plastics within the generated vortex.

If the inertial force was higher than the drag force applied to the robot by changing the rotating magnetic field condition, the swimming mode of the magnetic robot group could be switched from rotating to linear translational swimming. When a group of magnetic robots swam in a straight translation way at high speed, it was possible to block microparticles from entering a particular area or trap microparticles transferred into the area.

Professor Wie said, "This study is expected to be applicable to applications such as microplastic capture, drug delivery, and vortex control in microfluids."

The findings' paper, "Multimodal Collective Swimming of Magnetically Articulated Modularly Nanocomposite Robots," was published on November 8 in the internationally renowned journal, Nature Communications (IF=17.694). Won Soo-kyung in her Ph.D., majoring in Research Institute of Industrial Science at Hanyang University and Polymer Environmental Convergence Engineering at Inha University, and Lee Hee-eun, graduate from Polymer Environmental Convergence Engineering major of Inha University participated as co- first authors and conducted a joint study with Professor Yang Seung-jae’s research team of Inha University. It was also conducted with the support of the Basic Research Project (Medium Research) conducted by the Ministry of Science and ICT, the U.S. Air Force Research Institute, and the Korea Institute of Science and Technology.