Development of Bendable Ultrasonic Scalpel with Grasping Mechanism Using Superelastic Alloy Active Blade

In this study, we developed a multi-degree-of-freedom (multi-DOF) ultrasonic scalpel equipped with a superelastic alloy (NiTi) active blade that enables both tip bending and grasping motions.The active blade features a strip-shaped localized flexible section to facilitate compact bending, while a multistage hinge-based wire-driven mechanism achieves a bending range of ±60°.A blade-straddling single-moving-jaw grasping mechanism was also incorporated to provide grasping capability within the limited 8 mm outer diameter without interfering with the centrally routed active blade.The ultrasonic transducer can be easily detached from the active blade and replaced.A prototype device was fabricated on the basis of an active-blade design obtained by estimating the blade's ultrasonic resonance using the finite element method, and its fundamental performance was evaluated through excitation experiments and noncontact 3D vibration measurements.In the straight, unloaded posture, the active blade exhibited a resonant frequency of 57.5 kHz and a transducer current of 528 mA at a driving voltage of 25 V. Stable ultrasonic resonance was maintained even in the bent state; however, vibration amplitude attenuation and durability issues were identified as major challenges.In cauterization experiments using an edible porcine meat sample, the grasping mechanism enabled effective wide-area cauterization in the straight posture, whereas sufficient cauterization was not achieved when the tip was bent.