Magnetics microrobots remove blood clots from sheep iliac artery

4 March 2025

Researchers at the TechMed Centre of the University of Twente and Radboud University Medical Center have removed blood clots with wireless magnetic robots. This innovation promises to transform treatment for life-threatening vascular conditions like thrombosis.

Cardiovascular diseases such as thrombosis are a major global health challenge. Each year worldwide, one in four people die from conditions caused by blood clots. A blood clot blocks a blood vessel preventing the blood from delivering oxygen to certain areas of the body.

Minimally invasive

Traditional treatments struggle with clots in hard-to-reach areas. But magnetic microrobots bring hope to patients with otherwise inoperable clots. The screw-shaped robots can navigate through intricate vascular networks since they are operated wirelessly.

In a new study, researchers Islam Khalil (University of Twente) and Michiel Warlé (Radboudumc), showcase the potential of these microrobots for precise and minimally invasive clot removal. In their experiments, the microrobots removed enough material of a blood clot inside an iliac artery to resume blood flow. The iliac artery, obtained from sheep, was chosen as due to its straight and accessible structure.

Three methods

The research highlights three methods for removing blood clots: mechanical fragmentation, chemical dissolution, and a combination of both. The combined approach is the most consistent and safest, as it breaks up clots and dissolves the fragments. “By completely dissolving them, we remove the possibility of them travelling downstream and causing a new blood clot”, explains Warlé. With X-ray guidance, the tiny robot accurately targets clots in complex blood vessels.

 Islam Khalil (left) and Michiel Warlé

“The cross-Atlantic collaboration was incredibly rewarding for my team. These robots are designed to swim and perform surgeries deep inside the body, but researchers have been limited to using clear models and video cameras, or ultrasonic probes with limited range. Real-time X-ray guidance of these tiny robots is an essential leap forward in this area. We’ve long imagined what it looks like, but now we have 3D reconstructions of blood clots as the robot dissolves them", says Aaron Becker, researcher at the University of Houston.

The robots are 3D-printed and shaped like tiny screws, each containing a small permanent magnet. “This tiny magnet, just one millimetre long and one millimetre in diameter, is positioned to rotate the ‘screw’ in both directions,” explains Khalil. “This allows the robot to swim against the flow and then turn around to swim back.” The screw-like design allows them to drill through blood clots effectively.

Other applications

In addition to breaking up blood clots and restoring blood flow in arteries, the technology has the potential for other targeted treatments. “The robots can deliver drugs directly to specific areas in the body where they are needed most,” explains Khalil. “This approach minimises side effects in the rest of the body.”

More information

This research has been a strong collaboration between the University of Twente (RAM-Robotics and Mechatronics, TechMed Centre, Biomechanical Engineering) and the Radboudumc (HealthTech Nexus) and other universities worldwide (German University in Cairo, University of Houston and The Hebrew University of Jerusalem).

Michiel Warlé is associatie professor vascular surgery and perioperative care at Radboudumc.

Dr. Islam Khalil is associate professor, Robotics and Mechatronics (TechMed Centre). His research interests include amongst others the modelling and design of motion control systems for soft microrobots and biologically-inspired microrobots.

Their article, entitled “Wireless Mechanical and Hybrid Thrombus Fragmentation of Ex Vivo Endovascular Thrombosis Model in the Iliac Artery”, was published in the scientific journal Applied Physics Reviews and can be read online.

Michiel Warlé was interviewed on the topic on Dutch national radio by Humberto on Friday 28 February 2025.

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