A large air gap magnetic levitator for intra-arterial positioning of a clinical microcatheter: design, fabrication, and preliminary experimental evaluation

Radioembolization, a targeted treatment for advanced-stage liver cancer, is a medical procedure in which millions of radioactive microspheres (20–40 µm in diameter) are released into the blood vessels feeding liver tumors. These microspheres not only reduce blood flow to the tumors; their associated radiation kills the cancerous tissues into which they embed. While effective, this procedure also poses a threat to adjacent (non-target) healthy liver tissues. Recent research (both theoretical and experimental) has established a strong relationship between microsphere injection location (in the artery cross section) and the destination vessel, demonstrating the potential for specific vessel and tumor targeting. One such method for positioning the catheter tip, the subject of this research, is to use magnetic levitation. This paper (the second of a two-part series) details the design, fabrication, and preliminary testing of a large air gap magnetic levitator. This device, with a model-based sliding mode controller, is used to precisely position the microcatheter tip in a dynamically perfused arterial model cross section, allowing for microsphere injections from controlled locations within the cross section. Microsphere distributions were found to be significantly dependent on release location, and the large gap levitator is shown to be a viable option for catheter positioning.