Bio-inspired Magnetic Robots for Tortuous Surgical Navigations: From Shape-forming Tentacles to Tip-growing Vines

There are areas of the body which cannot be surgically accessed without associated risk of tissue trauma. This thesis concerns itself with the design of miniaturised surgical robots designed to navigate deep within the anatomy in a minimally invasive manner. This work considers the navigation of tortuous lumina, such as those found in the bronchial tree of the lungs where the level of curvature required is notably high, and for traditional catheter designs requires large insertion forces at the proximal end of the device.

To counter these challenges, this thesis proposes bio-inspired robots for navigation of such environments. The first is a tentacle-like magnetic catheter designed to reduce interaction forces by full shape control. These miniature robots are fabricated based on a computational design process. To aid in this, the thesis develops a fully opensource continuum mechanics framework for simulation of magnetic soft structures to create patient-specific robot designs based on the Material Point Method. Follows is a discussion of the application of these robots and its associated challenges, particularly when high deformation and dexterity are required. After which. the thesis introduces
a new class of continuum robot inspired by the movement of plant vines. This robot named the Magnetic Vine Robot (MVR), is formed of an entirely soft, flexible structure
and contains a magnetic element therefore enabling steering under externally applied magnetic fields. Further, under internal fluidic pressure the robot propels itself forward moving without relative friction with the external environment enabling navigation of tortuous lumina. Proposed are two such MVR designs, the first formed of a magnetic skin and the second containing a magnetic liquid. These are then evaluated in a range of diameters from 4 - 8 mm. Our unique approach, retains the soft structure of the
robot allowing it to squeeze through small gaps, passively conform to the environment and capable of high curvature and stabilisation. These novel robot designs are then demonstrated in navigating tortuous anatomy both on table-top environments and then in realistic physical phantoms as pre-clinical studies, paving the way for their potential application in the real-world surgical environment.