The microrobot the researchers use comprises a proprietary spherical capsule made of a soluble gel shell that they can control with magnets and guide through the body to its destination. Iron oxide nanoparticles in the capsule provide the magnetic properties. “Because the vessels in the human brain are so small, there is a limit to how big the capsule can be. The technical challenge is to ensure that a capsule this small also has sufficient magnetic properties,” explains Fabian Landers, lead author of the paper and a postdoctoral researcher at the Multi-Scale Robotics Lab at ETH Zurich.
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To test the microrobots and their navigation in a realistic environment, the researchers developed silicone models that accurately replicate the vessels of patients and animals. These vessel models are so realistic that they are now being used in medical training and are being marketed by ETH spin-off Swiss Vascular. “The models are crucial for us, as we practised extensively to optimise the strategy and its components. You can’t do that with animals,” explains Pané. In the model, the researchers were able to target and dissolve a blood clot.
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After numerous successful trials in the model, the team sought to demonstrate what the microrobot could achieve under real clinical conditions. First, they were able to demonstrate in pigs that all three navigation methods work and that the microrobot remains clearly visible throughout the entire procedure. Second, they navigated microrobots through the cerebral fluid of a sheep. Landers is particularly pleased: “This complex anatomical environment has enormous potential for further therapeutic interventions, which is why we were so excited that the microrobot was able to find its way in this environment too.”
From the article:
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