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.

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