Steerable Guidewire With Eyes for Image-Guided Intervention in the Upper Urinary Tract

Active steering at the distal tip can reduce stress on the flexible ureteroscope (FU) shaft by eliminating the internal angulation wires while also minimizing tissue trauma. A multi-segmented SMA wire actuator has been designed to produce smooth graded motion of the ultrathin scanning fiber endoscope (SFE). A steerable SFE distal tip (1-axis) is demonstrated using a three-step graded bending motion with a multi-tapped shape memory alloy (SMA) wire, power transistor switches, and binary parallel communication. The experimental bending radius and angle of the fabricated active tip (2-mm OD) is measured as 45-mm and 50°, respectively. Using nominal 4% strain of a 125-μm SMA wire, the experimental values are compared to the model predictions using a multi-link planar manipulator. A guidewire with eyes and active tip bending mechanism constitutes the new SFE, which is expected to reduce the procedural time and complications, eliminate X-ray guidance, and provide more space for adjunctive instrumentation, along with having better performance and possibly lower cost than FU.