The team described the "magnetically steerable, hydrogel-coated robotic thread" in a paper published in Science Robotics. The core of the thread is made from nickel-titanium alloy, which is both bendy and springy. It's coated with a rubbery paste, or ink, which is embedded with magnetic particles. That's then covered with a hydrogel, which makes the wire smooth and friction-free, and the final product can be controlled using magnets.

Today, surgeons typically clear blood clots in the brain by inserting a thin wire through a person's main artery. The surgeons use a fluoroscope, which images the blood vessel using X-rays, to manually rotate and guide the wire into the damaged brain vessel. A catheter is then threaded along the wire to deliver drugs or other clot therapies. But the procedure is physically taxing on the surgeons, who are exposed to repeated radiation from the fluoroscope. And the wires carry the risk of damaging the vessel linings.

In contrast, this robotic thread is controlled by magnets, and surgeons could guide it from outside of the operating room. They'd be protected from repeated radiation exposure, and they might be able to perform procedures remotely using a joystick. Yes, remote robotic brain surgery using a joystick.

Thanks to the hydrogel, there's less risk of friction against the vessel linings, and the device could help surgeons reach even further into the brain. "One of the challenges in surgery has been to be able to navigate through complicated blood vessels in the brain, which has a very small diameter, where commercial catheters can't reach," said Kyujin Cho, professor of mechanical engineering at Seoul National University. "This research has shown potential to overcome this challenge and enable surgical procedures in the brain without open surgery."

The robotic thread isn't ready for clinical use, but the team demonstrated its agility by steering the thread through an obstacle course of small rings, similar to threading a needle. They also created a life-sized replica of the brain's major blood vessels and guided the robot through those winding, narrow paths. Eventually, they hope the robotic wire might deliver clot-reducing drugs or break up blockages with a laser.