Researchers from the University of Twente (UT) and the Radboudumc have succeeded in making minuscule robots swim through narrow blood vessels. In doing so, the robots were controlled using a rotating magnet. The technology could be of interest for removing blood clots, among other things.
Blood clots can lead to a variety of life-threatening conditions; one in four deaths each year is due to conditions caused by blood clots. Such a clot can block a blood vessel, preventing blood from delivering oxygen to certain parts of the body.
Removing blood clots in hard-to-reach places
Surgeons currently use flexible instruments to remove blood clots. In practice, however, some parts of the body are difficult to reach. With their micro-robots, the researchers aim to provide a solution and simplify the removal of blood clots in such locations.
That microrobots can travel through veins the researchers have now demonstrated. In doing so, they used a robotically controlled rotating magnet to send helical robots through a detached aorta containing 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.
Wirelessly guided through the blood vessel
The rotating magnet was controlled using a robotic arm. Using this, the researchers sent the microrobots wirelessly through the blood vessel. During the experiment, the researchers used an X-ray machine to locate the microrobots as they moved through the aorta. This used a maximum blood flow in the aorta of 120 ml per minute. However, with a strong magnet, the microrobots can also swim through stronger currents, say the researchers.
The micro-robots in question were 3D-printed by the researchers and fitted with a small permanent magnet. "We placed this tiny magnet of only a millimetre in length and a millimetre in diameter so 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 said.
Drilling through blood clots
The robots are screw-shaped. By rotating the robots, their shape allows them to drill through blood clots. This is how the robots remove the blood clot.
"These millirobots have enormous potential in vascular surgery," states Michiel Warle, vascular surgeon at Radboudumc. "Currently, we use blood thinners and flexible instruments, but a millirobot can swim to hard-to-reach arteries. This requires only minimal incisions to insert them."
Further development with grant
The researchers will now further develop the microrobots in collaboration with the Radboudumc and Israeli Triticum Medical. This should enable deployment of the robots in practice for wireless removal of blood clots. The researchers are also investigating other ways to deploy the technology. In addition to removing blood clots, other applications are conceivable. These include delivering drugs to very specific locations in the body, which helps minimise side effects. To further develop the technology, the researchers recently received a grant from Health Holland. This is a TKI-LSH (Top Consortia for Knowledge & Innovation - Life Science & Health) grant for public-private partnerships.
The research was funded from the TURBO programme (Twente University RadBoudumc Opportunities). This programme helps research groups from both institutions to develop innovative ideas into large-scale research projects. Also watch this video, in which the researchers visualise their experiment.
Author: Wouter Hoeffnagel
Image: Vector8DIY via Pixabay
