A Novel Ultrasonic Scalpel Rod with Multi-Stage Gain and Minification Structures for Minimally Invasive Surgery

This paper presents a novel ultrasonic scalpel rod (USR) with a multiple stage amplification scheme that consists of both functional minification and gain structures for ultrasound vibration. The vibration amplitudes are first suppressed during the ultrasound transmission along the ultrasonic scalpel rod to reduce the friction energy loss, and then are enlarged at the distal end for tissue cutting. In order to further improve the cutting ability, the distal blade structure of the ultrasonic scalpel has been improved to a rectangular shape. The finite element method (FEM)-based simulations have been performed to investigate both static and dynamic performances to analyse the characteristics of the designed ultrasonic scalpel rod. The simulation results show that the amplification ratio of vibration amplitude can reach around 6.5, and the ratio between the maximum axial deformation and the maximum radial deformation is 51.2, with the working frequency of 55. 554kHz. Computerized Numerical Control was utilized to fabricate the monolithic structure of the ultrasonic scalpel rod mechanism, and its cutting performance was verified through the liver cutting experiment.