A concentric tube catheter for endoluminal interventions, steered and imaged via magnetic resonance imaging

Two major challenges associated with robotic catheterization are, firstly, the provision of controllable degrees of freedom (DoFs) and, secondly, accessing feedback on the shape and pose of the catheter. Miniaturizable active steering can be achieved through magnetic actuation, and Magnetic Resonance Imaging (MRI) provides high definition, radiation-free 3D imaging that can be utilized for shape-sensing. Here, we propose a structurally adaptable Coaxial Sleeve Magnetic Actuator (CoSMA), with deformation energy provided by the background field of the MRI scanner. Our approach combines the magnetic actuation principle of the easy axis of alignment with the mechanical principles of concentric tube designs. This concept allows for a materially flexible ( $E=O\left(1\mathrm{MPa}\right)$ ), and therefore risk reduced, multi-DoF catheter. We demonstrate the CoSMA, constructed of three coaxial components with respective outer diameters of 4 mm, 1.5 mm and 0.4 mm, in an aortic arch phantom navigation within the bore of a pre-clinical MRI scanner.