MIT's new robotic wire seamlessly moves through sensitive blood vessels.

One of the most challenging aspects of brain surgery is navigating through the organ’s network of approximately 400 miles of tiny blood vessels — not to mention around 100 billion nerve cells. On top of that, strokes and other life-threatening conditions make brain surgery a procedure that must be performed quickly and flawlessly.

To clear clots in the brain, surgeons often use a fluoroscope, which takes X-ray images of the blood vessels and enables them to physically turn and direct a medical wire into the clotted one. A catheter is strung along this wire to transport the appropriate medicines to the area.

Unfortunately, many of these wires have cores made from metallic alloys. If one of them gets jammed en route and has to be prodded to continue on its path, there’s a high risk that the resistance would damage the delicate linings of the blood vessel.

Not only is this course of action risky for the patient, but it also puts surgeons and other medical personnel at risk, as the fluoroscope itself repeatedly exposes doctors to radiation.

MIT Ingenuity

X-Ray of a brain with a blood clot

Now, a team of MIT engineers has produced a thread-like robotic fiber that can move smoothly throughout the brain’s labyrinth of blood vessels without risk of damage to the fragile vessel walls. Not only could medications be more safely and easily transported by this method, but it could also eliminate the need for open brain surgery, because it would enable surgeons to operate not only outside of the operating room, but from practically any location. The double advantage of this would be no radiation exposure for these surgeons, and the ability to save patients in remote locations.

How It Works

The MIT team developed what was described in a paper published in Science Robotics as a “magnetically steerable, hydrogel-coated robotic thread.” The core of the thread is made from nickel-titanium alloy that’s both flexible and spongy, and is layered with a rubbery ink or adhesive which itself contains an abundance of magnetic elements. The exterior is then coated with a hydrogel, which makes the wire glide smoothly and without friction. And since it can also be easily manipulated by magnets, that also means no more dangerous exposure to radiation.

The Trials

Although the new procedure hasn’t been tested on humans quite yet, the MIT team is busy putting it through a slew of other trials to make sure it’s perfect. They first tested the thread’s suppleness by running it through an obstacle course of tiny rings (akin to threading a needle and using a large remote magnet to guide it). As expected, the newfound malleability allowed the wire to easily bend and twist without creating friction.

Doctors perform surgery on a patient.

The team then built a full-scale model of a human brain to test the procedure. Again, the wire performed flawlessly, easily navigating every twist and turn presented in the slender blood vessels, supporting the theory that it could eventually be used to disintegrate blockages and carry life-saving drugs to every nook and cranny in the brain’s mass.

Hope for the Future

Xuanhe Zhao, Associate Professor of Mechanical, Civil, and Environmental Engineering at MIT, is optimistic about the future. He explains: “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. 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.”