A concentric tube magnetic continuum robot with multiple stiffness levels and high flexibility for potential endovascular intervention

Micromagnetic continuum robots (MCR), renowned for their simple structure and high flexibility, hold immense potential and scientific significance in the fields of biomedicine and clinical therapeutics. MCRs are exceptionally adept at navigating confined spaces to transport surgical instruments such as biological valves and drugs, which are crucial for minimally invasive surgeries and delivering nanomedicines over long distances. However, traditional MCRs suffer from a single stiffness and limited maneuverability in complex workspaces. To overcome this problem, we propose a novel multi-stiffness and highly flexible concentric tube magnetic continuum robot (CT-MCR). The CT-MCR consists of conduits of varying diameters, magnetic particles, and a bundle of magnetic thin flexible tubes. It offers the flexibility to be disassembled and assembled to build working channels, and it possesses diverse working modes and body stiffness levels to accommodate specific working requirements. Due to the excellent magnetic field performance of supporting N52 neodymium magnets, the CT-MCR has a significant bending angle and superior maneuverability. Experimental results demonstrate that the CT-MCR is capable of navigating and recovering foreign objects within complex branching vessel models in the workspace of a three-dimensional (3D) Helmholtz coil. The CT-MCR's exceptional maneuverability, flexibility, and adaptability, coupled with its low risk and extensive workspace, are expected to find applications in Transcatheter Aortic Valve Implantation (TAVI) and other minimally invasive surgeries, as well as in the long-distance delivery of targeted drugs.