July 2024
Using a robotically controlled rotating magnet, researchers from the University of Twente and Radboud UMC (both in the Netherlands) steered helical millirobots through a narrow blood vessel, both with and against the flow. The aim is to have them remove blood clots.
Every year, one in four people worldwide die from conditions caused by blood clots. Surgeons use flexible instruments to remove the blood clot, but some parts of the body are difficult to reach. With their small size, the millirobots can reach these places.
The millirobots can swim against the current as well as with the current and can be controlled and localized very accurately. In order not to damage the blood vessels, they are also biocompatible.
For their experiment in the Technical Medical Center of the University of Twente, the researchers used a real aorta and kidneys. “This required an interdisciplinary approach and collaboration between many different departments: The Robotics Lab, Laboratory of biointerface, blood lab, DesignLab, LipoCoat and MESA+ all helped us achieve this result,” says researcher Islam Khalil.
For the experiment, the researchers used a rotating magnet controlled by a robotic arm to send the millirobots wirelessly through the blood vessel. They used an X-ray machine to locate the millirobots as they swam through the aorta. The researchers used a maximum blood flow in the aorta of 120 ml per minute. But with a stronger magnet, the millirobots can swim through a stronger current. The millirobots swam stable straight stretches with the current and against the current. This was possible with one, but also with several millirobots at the same time.
The millirobots themselves are 3D printed, helical objects with a small permanent magnet inside. "We placed this small magnet, only a millimeter long and a millimeter in diameter, in such a way that it can turn the 'screw' in both directions. This makes it possible to swim against the current and then turn around and swim back," Khalil says. The small size makes it possible to use multiple millirobots at the same time. And the screw shape means they can drill through a blood clot.
"These millirobots have enormous potential in vascular surgery," says Michiel Warle, vascular surgeon at Radboud university medical center. “We currently use blood thinners and flexible instruments, but a millirobot can swim to hard-to-reach arteries. This requires only minimal incisions to insert them."
Together with Radboudumc and Triticum Medical (Israel), the researchers will further develop the millirobots so that they can remove blood clots wirelessly. The consortium is investigating ways to exploit this technology.
In addition to removing blood clots, other applications are conceivable. "The millirobots can deliver medicine where necessary. That way we have minimal side effects in the rest of the body," Khalil says.
Reference(s).. www.utwente.nl & other media