MIT’s snake-like robot slides through blood vessels in the brain

6 Sep 2019

Engineers at MIT have created a magnetically controlled threadlike robot that glides through the narrow pathways, such as the labyrinthine vasculature of the human brain. Their research is published in journal Science Robotics.

The robotic thread (in black) can be steered around blood vessels in a brain by using large magnets. Researchers hope the new technology will be used in the future to clear out blockages in patients who suffered from strokes and aneurysms. (Image Credit: MIT)

This could be used by doctors in the future by pairing them with existing endovascular technologies, allowing the robot to be remotely navigated through a patient’s brain, treating blockages or lesions that occur as a result of a stroke or aneurysms. Existing methods to clear out blockages or treat lesions involve a catheter which is manually threaded by a surgeon, with the assistance of a guidewire. Coming up with more efficient, alternative methods could save lives and reduce the physical strain carried out by surgeons, while limiting exposure to an X-ray imaging tool known as fluoroscopy.

“Stroke is the number five cause of death and a leading cause of disability in the United States,” Xuanhe Zhao, an associate professor of mechanical engineering at MIT, said. “If acute stroke can be treated within the first 90 minutes or so, patients’ survival rates could increase significantly. 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 team has benefited from previous research in both hydrogels and 3D-printed materials that can be controlled by magnetism, enabling the materials to crawl, jump, and catch a ball. Researchers combined their previous work using hydrogels and 3D printed materials controlled by magnets to develop a magnetically steerable, hydrogel-coated robotic thread embedded with particles that give it magnetic properties. The snake-like robot has a nickel-titanium alloy in its center, allowing it to bend with ease while maintaining its springy form.

The engineers also demonstrated the precision and activation of the robotic thread by using a large magnet to steer it through an obstacle course of small rings, similar to moving a thread through the eye of a needle. It was also tested in a life-size silicone replica of a human brain’s major blood vessels, which was modeled from CT scans of a patient’s brain. The team also filled up each silicone vessel with a special liquid that imitates the viscosity of blood. Afterward, the team was able to steer the robot through the narrow vessel pathways by manipulating a magnet around the model brain.

Additional features can also be added to the robot, giving it a wider sense of functionality. It can deliver drugs in the brain to reduce blood clots or break up blockages by using laser light. The team demonstrated the ability to do the latter by replacing the thread’s nickel-aluminum core with an optical fiber and discovered they could also steer the robot with a magnet and turn on the laser light when the robot reached a specified area.

Researchers also found that, when comparing the robotic thread coated vs. uncoated with hydrogel, they discovered the hydrogel allowed the robot to move through tight spaces with ease, without getting stuck. This gives it an advantage it endovascular surgery, especially because it wouldn’t have friction applied to it and there wouldn’t be any injuries to the vessel linings as it moves through them. It also keeps surgeons free from exposure to radiation since they wouldn’t have to be in close proximity with a patient and wouldn’t need to be close to a fluoroscope, which produces radiation.

In the future, endovascular surgeries that use magnetism, with large magnets or by manipulating magnets around a patient’s brain could easily be carried out outside the operating room, away from the fluoroscope imagine the patient’s brain, or in a different area.