Minaturized Magnetic Vine Robots for Deep Endoluminal Navigation

Vine robots are a form of soft continuum robot formed of a thin-wall cylinder which has been partially inverted. When pressure is applied internally, the inverted material is propelled outwards causing the body to extend [1] (See Figure 1). This unique form of navigation facilitates shear-free locomotion and high tip force, leading to their proposed use in endoluminal interventions [2]. These properties have the potential to minimize potential traumatic tissue interactions and, due to their inherent minaturizability, facilitate navigation deep within the anatomy. When pressure is applied, vine robots intrinsically follow the forward path of least resistance, passively navigating around obstacles and forming curvatures in their everted body. However, these robots lack the ability to steer their direction of growth in the absence of additional mecha- nisms. Steering methodologies such as series pneumatic artificial muscles employ expanding actuators along the length of the robot. These offer modest deformation but preserve the soft structure of the robot body [1], [3]. Alternative approaches include tendon-driven designs which provide much greater angles of curvature however sacrifice the fully-soft structure [2]. The use of magnetic fields for surgical devices has been proposed at several scales. Via manipulation of the magnetic field within the workspace, forces and torques can be applied to internal magnetic elements. Continuum robots have been developed with entirely soft structures embedded with magnetic micro-particles. These robots are capable of being fabricated at small- scale (less than 2 mm diameter) whilst being steered via control of electromagnetic coils or External Permanent Magnets (EPMs) [4].