A thread-like robot steered by magnets could treat blood clots in stroke patients to prevent brain damage. The flexible robot was designed by researchers at MIT to slide through the brain’s blood vessels without getting stuck.


The team hopes that the bot will replace the traditional method of treating blockages and lesions, which currently involves a surgeon inserting a thin wire into a major blood vessel in the patient’s leg or groin and directing it into the brain by hand. Not only is this process difficult any wrong moves can potentially cause further damage. It is also potentially harmful to the surgeon as the location of the wire in the blood vessel using a real-time X-ray (known as fluoroscopy), exposing them to repeated doses of radiation.

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“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 associate professor Xuanhe Zhao. “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 robot thread has a thin wire core made of a springy nickel-titanium alloy, coated in a rubbery ‘ink’ that is embedded with magnetic particles. Around the core is a thin layer of a ‘hydrogel’, a soft, non-toxic, water-based material which gives the robot a smooth surface to reduce the chance of damaging the blood vessels or getting stuck.

Currently, the robot is controlled by hand: the team have tested it in a silicone model of a stroke patient’s brain, directing the robot thread by moving a magnet around the outside of the model. However, in the future, the surgeon could control the magnets from a distance, avoiding the need to be exposed to X-ray radiation.

“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 Yoonho Kim, the paper’s lead author.


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