A thread like a robot can provide therapy to reduce blood clots

MIT engineers have developed magnetically controlled thread-like robots that can actively glide in narrow and curved lanes such as the brain’s labyrinthine blood vessels.

In the future, these robot seams can be combined with existing endovascular technology so that doctors can direct the robot remotely through the patient’s brain to quickly treat obstructions and lesions such as those found in aneurysms and strokes.

“Stroke is the fifth leading cause of disability in the United States, and if an acute stroke can be treated in the first 90 minutes or so, the patient’s survival rate can increase significantly, said Xuanghe Zhao, Assistant Professor of Mechanical and Environmental Engineering at MIT.

If we can develop a tool that can reverse the blockage of blood vessels in this golden hour, we might be able to avoid permanent brain damage. That is our hope.

Zhao and his team, including lead author Joonho Kim, a graduate student in the MIT Department of Mechanical Engineering, today described their soft robot design in Science Robotics.

To get rid of blood clots in the brain, doctors often perform endovascular procedures, minimally invasive surgeries in which the surgeon inserts a thin wire through the patient’s main arteries, usually the legs or groin.

Encouraged by a fluoroscope that simultaneously displays blood vessels using X-rays, the surgeon manually turns the wire into a damaged brain blood vessel. The catheter can then be hung to give medicine or a device to remove blood clots in the affected area.

Kim said this procedure can provide physical benefits and requires surgeons who need special training in the task of resisting repeated exposure to fluoroscopy.

This is a challenging skill and there are not enough surgeons for patients, especially in the suburbs or rural areas, Kim said.

The medical wires used in such procedures are passive, that is, they must be manipulated manually and are usually made of a polymer-coated metal alloy core which, according to Kim, has the potential to cause friction and damage the lining of vessels if the wire is temporarily very tight . Room crashing.

The team recognizes that developments in his laboratory can help improve such endovascular procedures, both in the design of the driver and in reducing the doctor’s exposure to radiation related.

In recent years, the team has built expertise on biocompatible hydrogel materials, which are mainly water and 3-D printed materials that are magnetically driven and can be designed to crawl, jump and even pick up the ball by simply following the direction the magnets follow.

In this new article, the researchers combined their work with hydrogels and magnetic actuation to make robotic filaments or magnetically controlled control wires, thin enough to make magnetic-silicon replicas of brain blood vessels.

The core of the robotic filament consists of nickel-titanium alloy or Nitinol, a bent and spring-loaded material. Unlike hangers which retain their shape when bent, nitinol wires return to their original shape and provide more flexibility when winding through tight and twisted vessels.

Finally, they used a chemical process they had previously developed to cover and bind the magnetic layer to the hydrogel, a material that does not interfere with the sensitivity of the underlying magnetic particles and still provides a smooth, friction, biocompatible surface wire.

They demonstrated the accuracy and operation of robotic threads with the help of large magnets, similar to puppet yarn, to attach thread through a barrier made of small rings reminiscent of threads moving through the eye of a needle.

The researchers also tested large-scale silicone threads in large cerebral blood vessels, including blood clots and aneurysms, which were modeled after CT scans of the actual patients’ brains. The team filled the silicon container with a fluid that simulated blood viscosity and then manually manipulated the large magnets around the model to guide the robot through coils and narrow ways of the ship.

The authors also tested silicone threads on the main sizes of major brain blood vessels, including clots and aneurysms, which were modeled after CT scans of the actual patients’ brains.

They fill the silicon vessels with fluid that simulates blood viscosity and then manually manipulate large magnets around the model to guide the robot through curves and narrow pathways of vessels. Robotic threads can be used, meaning functions can be added to provide drugs, reduce blood clots, or destroy laser blockages, for example.

Thanks to a magnetically controlled conductor, the surgeon no longer needs to push the wire through the patient’s blood vessels. This means that the doctor must not be near the patient, and more importantly, that the fluoroscope produces radiation.

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