Tiny robotic thread can slip through brain’s blood vessels

Henrietta Strickland
August 30, 2019

Researchers from the Massachusetts Institute of Technology (MIT) created a robotic thread core made from bendy, springy nickel-titanium alloy, and they coated the wire core in a rubbery paste filled with magnetic particles.

The material is coated in an ink-like substance, which is then bonded with a hydrogel, regulating in a magnetically manipulable material that can still surviving within the human body.

The device could be controlled to deliver clot-reducing therapies and reverse blockages within vessels in the hope of avoiding permanent brain damage and potentially saving lives. The wires are generally metallic and polymer, which can cause friction or cause them to get stuck in tight places, according to the MIT team.

Additionally, the scientists hope to expand functionality of their robotic thread with certain modifications, such as fixing a device for drug delivery to the end or to treat clots using light.

The new development from MIT researchers combines robotics with current endovascular (ie. within blood vessel) surgery techniques, reducing the risks associated with guiding incredibly thin wires through complicated brain blood vessel pathways.

It is a potentially unsafe procedure for which too few surgeons are sufficiently trained, and it also exposes the doctor to high amounts of radiation from the x-rays which map the blood vessels for them.

The researchers tested the thread in a life-size silicone replica of the brain's major blood vessels modelled after scanning an actual patient's brain.

It is then coated with hydrogel, a material that does not affect the responsiveness of the underlying magnetic particles and yet provides the wire with a smooth, friction-free, biocompatible surface.

The team demonstrated that the thread's wire core can also be replaced with an optical fiber that can activate the laser once the robot reached a target region to clear blockages. The researchers liken control of the robotic thread to pulling the strings of a marionette, and were able to steer the wire through the replica's narrow paths. "This research has shown potential to overcome this challenge and enable surgical procedures in the brain without open surgery".

As for reducing radiation exposure to surgeons, Kim said the magnetic component of the robotic thread removes the need for surgeons to physically push a wire through the patient's blood vessels, which means they won't be as close to the patient and the radiation-generating fluoroscope.

"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", Kim said.

Lead author Yoonho Kim said the next step was to test the robotic thread in a living organism.

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