When we think of robots that can be used to help with medical procedures, we tend to conjure up images of a humanoid robot helping surgeons, or some kind of bulky device with robotic arms to help with the operations. But robots can be tiny and not even remotely look like anything you’ve seen in science fiction movies.
MIT engineers, for example, have created a thread-like robot that can travel through your brain's blood vessels to treat blockages and can deliver medication to treat strokes or aneurysms.
These MIT engineers, who specialise in both hydrogels and magnetically-actuated materials, were able to combine their expertise in both these two areas to create what they call a “magnetically steerable, hydrogel-coated robotic thread”.
In a new paper published in Science Robotics, they described the core of the robotic thread as being made from “nitinol” or nickel-titanium alloy, a material that’s both bendable and springy. This is what will allow the thread to have the flexibility to make its way through blood vessels.
The way surgeons today clear blood clots in the brain today is by a thin wire through a person's main artery, usually in the leg or groin. The surgeons then use a fluoroscope (which images the blood vessel using X-rays) to manually guide the wire along blood vessels until it reaches its target destination. A catheter is then threaded along the wire to deliver the necessary medications.
There are two clear downsides to this approach. Firstly, the wires used in such procedures are made from a core of metallic alloys, coated in polymer, a material that could potentially generate friction and cause damage to vessel linings if the wire were to get temporarily stuck in a particularly tight space. Secondly, these wires are passive, meaning they must be manipulated manually by surgeons on the scene. Unfortunately, this means these surgeons are repeatedly exposed to radiation from the fluoroscope.
HOW IT WORKS
The robotic thread developed by the MIT engineers is coated with a rubbery paste which is embedded with magnetic particles. It’s also covered with a hydrogel which makes it frictionless and thus less likely to cause damage to blood vessels. With the thread being controllable via magnets, surgeons could guide its passage from outside of the operating room and thus be shielded from repeated exposure to radiation.
The team has tested its agility by steering the thread through an obstacle course of small rings, similar to threading a needle. They had also created a life-sized, silicone replica of the brain's major blood vessels (including clots and aneurysms) and guided the robotic thread through them. The team had filled the silicone vessels with a liquid simulating the viscosity of blood, then manually manipulated a large magnet around the model to steer the robot through the vessels’ winding, narrow paths.
The researchers say the robotic thread can be functionalised, meaning that features can be added to it. It can be designed to deliver clot-reducing drugs or break up blockages with laser light.
To demonstrate the laser concept, the team replaced the thread’s nitinol core with an optical fibre and found that they were able to magnetically steer the thread to the target region and activate the laser.
“Existing platforms could apply magnetic field and do the fluoroscopy procedure at the same time to the patient, and the doctor could be in the other room, or even in a different city, controlling the magnetic field with a joystick,” said the paper’s lead author, Yoonho Kim, a graduate student in MIT’s Department of Mechanical Engineering. “Our hope is to leverage existing technologies to test our robotic thread in vivo in the next step.”
PLENTY OF POTENTIALS
This opens up the prospects of patients in remote or rural areas with limited local medical expertise to be able to receive prompt, life-saving treatment via telemedicine from specialists at a city located far away.
Xuanhe Zhao, a member of the MIT team that developed the robotic thread, said it might even be possible to incorporate artificial intelligence into the device so that it could be operated by health care providers who are no specialists.
All this would mean considerably more patients could be treated quickly, before their brain tissues die due to lack of oxygen. “Stroke is the number five cause of death and a leading cause of disability in the United States,” said Zhao. “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.”
This robotic thread is still at prototype stage and is far from ready for clinical use. Zhao said tests of the device on animals might begin within a year or two, but that it might take a decade or longer before a commercial version of the device can really be ready to be used on humans.
Oon Yeoh is a consultant with experiences in print, online and mobile media. Reach him at [email protected].