MIT engineers have developed a robotic thread designed to move through the brain’s blood vessels. The magnetically controlled device could be an alternative to invasive brain-opening surgeries required to treat strokes and other neurological blockages.
The hydrogel-coated, thread-like robot can be magnetically steered to glide through narrow and winding pathways—ideal for navigating the labyrinth of blood vessels in the human brain.
In the future, the device could be paired with other technologies to allow doctors to guide the thread remotely—outside of the operating room or from a completely different location.
“Stroke is the number five cause of death and a leading cause of disability in the United States. If acute stroke can be treated within the first 90 minutes or so, patients’ survival rates could increase significantly,” said Xuanhe Zhao, associate professor of mechanical engineering and of civil and environmental engineering at MIT. “If we could design a device to reverse blood vessel blockage within this ‘golden hour,’ we could potentially avoid permanent brain damage. That’s our hope.”
The MIT team described the robotic thread in a paper published in Science Robotics. The thread’s core is made from nickel-titanium alloy, chosen for its bendy and springy nature. This is coated with a rubbery paste or ink, which is embedded with magnetic particles and covered with a hydrogel—a biocompatible material made mostly of water—to make the wire smooth and friction-free.
Current procedures to treat strokes and other brain aneurysms can be physically taxing on the doctors doing them, requiring specifically trained surgeons to endure repeated radiation exposure from fluoroscopy.
To clear blood clots in the brain, the surgeon must insert a thin wire through the patient’s main artery—typically in the leg or groin. A fluoroscope images the blood vessel using X-rays, while the surgeon manually rotates and guides the wire all the way up into the damaged brain vessel. A catheter is then threaded along the wire to deliver drugs or other clot therapies.
“It’s a demanding skill, and there are simply not enough surgeons for the patients, especially in suburban or rural areas,” says Yoonho Kim, a graduate student in MIT’s Department of Mechanical Engineering and a lead author on the paper.
The MIT team’s device, however, is controlled using magnets, and surgeons could guide it from outside of the operating room remotely, possibly even using a joystick.
Pretty cool, plus they would be able to bypass repeated radiation exposure.
Over the past few years, the team has conducted intense research in both hydrogels and 3-D-printed “magnetically-actuated materials” that can be made to crawl, jump and even catch a ball, simply by following the direction of a magnet.
Thanks to the hydrogel, there’s less risk of friction against the lining of the vessels, and the device could help surgeons move deeper 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 and another author on the paper. “This research has shown potential to overcome this challenge and enable surgical procedures in the brain without open surgery.”
The robotic thread is not yet ready for clinical use, but the team has demonstrated its agility by steering it through a life-size silicone replica of the brain’s blood vessels.
The engineers hope that eventually, the robotic wire might be able to deliver clot-reducing drugs to brain blockages or even break them up with a laser.
