Magnetics microrobots remove blood clots from sheep iliac artery

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 from a blood clot inside an iliac artery to resume blood flow. The iliac artery, obtained from sheep, was chosen due to its straight and accessible structure.

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.

“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. The 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.

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.”

This research falls under the banner of HealthTech Nexus, the strategic collaboration between Radboudumc and the University of Twente. Together, they are committed to the 'unmet need' of healthcare: urgent needs for which no good solutions yet exist. Within the UT, the following departments were involved: RAM-Robotics and Mechatronics, Faculty of TNW, TechMed Centre and Biomechanical Engineering. HealthTech Nexus worked closely with the German University in Cairo, University of Houston and The Hebrew University of Jerusalem for this research.

Dr. Islam Khalil is an Associate Professor in the research group RAM—Robotics and Mechatronics (Faculty of EEMCS / TechMed Centre). His research interests include the modelling and design of motion control systems for soft microrobots, biologically-inspired microrobots, mechatronic system design, and untethered magnetic micro/nanorobotics with applications to micro/nanomanipulation, micro-assembly, and targeted drug delivery.

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.

DOI: 10.1063/5.0233677