Thread-thin robots examine blood vessels with better accuracy

Engineers at MIT have developed a long, thread-like robot that is capable of precise movement within minuscule winding tubular systems, such as those typically found on the human body.

Medical procedures involving the insertion of thin metal wires or hollow tubes into the human circulatory system is not new. One common type of surgery, where the objective is to clear up a blood clot in the brain, requires the use of a medical guidewire, inserted into a major artery. It will then slowly work its way through the patient’s blood vessels until it reaches the blood clot. There, the surgeon will administer a drug, or do the next technical procedure necessary to clear it up.

While conceptually sound, executing this medical procedure in an actual emergency is often very taxing to the surgeons involved. Not only do they need the absolute precise manual accuracy to move inch-by-inch through the human body’s ever-narrowing blood vessels, but they must also account for the possibility that the wire itself might damage or scrape the blood vessel due to its material composition. There will always be an inherent risk in doing this procedure on the simple account of not having the option to make the slightest mistake.

MIT’s thread-robot however, technically circumvents these challenges by sheer dexterity. It is magnetically guided, which means that pushing further into the body remains intuitive, as you only need to point to the available direction where it has already reached. This is unlike an ordinary medical guidewire, which is controlled at its very end, thus requiring the calculation of every movement of each segment as it is pushed further.

The primary composition of the thread-robot is a nickel-titanium alloy, which is introduced as both “bendy and springy”. Nitinol, as it is called, has the tendency to return to its original state on its own, lessening the stress on the robot, as well as the risk of it eventually breaking off a portion of itself.’ In addition, this makes it inherently flexible while still having the rigid properties of being metal. Thus, it can slither its way through blood vessels much easier.

For its magnetically controllable properties, the outer casing of the robot is made of a rubbery paste, which is sprinkled throughout with magnetic particles. Using a considerably strong magnet, the particles will react accordingly, allowing the surgeon to direct it easily and intuitively.

As an added bonus, the thread-robot is also encased inside a type of hydrogel. This further enhances its flexible properties, as well as making the robot smooth, reducing the risk of damaging blood vessels as it travels through.

During its main test, the thread-robot was subjected to a 1:1 replica of the one of the human body’s major artery system. The system is filled with a special liquid that is made to resemble the viscosity of blood in room temperature. The robot, of course, passed with flying colors, making its way through the obstacle course as if it is some sort of a live worm parasite.

In the future, the MIT researchers who worked on the thread-robot, envision that it could be regularly used keep similar minimally-invasive procedures less dependent on multiple scanning instruments. Also, due no longer having the requirement to manually hold the wire, the surgeon could instead control a magnet system remotely, allowing such procedure to be conducted within separate locations.

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