Robotic Needle Steering by Concentric Beveled-Tip Tube and Wire

This paper presents a novel steerable needle robot designed for minimally invasive surgery (MIS) in tissue environments. The robot consists of a concentric configuration of a tube and a wire, both of which are constructed from superelastic (SE) nitinol and have beveled tips. The key innovation lies in controlling the relative rotation angle between the beveled tips of the tube and wire to adjust the steering direction and curvature of the robot during insertion into soft tissues. Unlike classic beveled-tip needles requiring continuous rotation of the robot body, our design enables the control of the motion trajectory through occasional rotation of the nested tube and wire, enhancing safety and minimizing tissue damage. Through non-dimensional analytical modeling, we determined the robot’s bending capability as a function of the design parameters, enabling us to select wires and tubes for a sufficiently large workspace and a minimal dead zone. Experimental evaluations with various combinations of beveled-tip angles validated the model predictions and design selections, demonstrating that the robot tip displacement significantly depends on the beveled tips and their relative rotation. The tested needle with 25° beveled tips at the wire and tube can achieve maximum tip displacement of 16.75 mm at an insertion of 70 mm when the beveled tips are aligned. The developed system demonstrated predictable and dexterous steering performance, highlighting its potential in MIS applications.