An enhanced hemostatic ultrasonic scalpel based on the longitudinal-torsional vibration mode

Abstract

This paper proposes an ultrasonic scalpel based on the longitudinal-torsional vibration mode to enhance the hemostatic ability. The concentrator of the proposed ultrasonic scalpel has been specially designed with spiral grooves to realize this vibration mode. The change of the working mode has enlarged the vertical motion component of the distal blade to efficiently radiate energy into the dissected tissues, supporting that the blood vessel can receive sufficient energy to be sealed. The electromechanical equivalent method has been employed in the initial design of the scalpel to obtain the desired resonance frequency. The structural optimization based on the finite element method (FEM) has been conducted to further improve the proposed design, as well as investigation of its dynamic performances. Both the conventional and presented ultrasonic scalpel prototypes were fabricated, and their important parameters such as, mechanical quality factor and resonance frequency, were tested and compared using an impedance analyzer. The ex-vivo experiments have been conducted to measure the vertical temperature distribution to investigate their transferring heat effects. The corresponding results indicated that the internal temperature values of tissues cut with the proposed hemostatic-enhanced ultrasonic scalpel are 24.0% higher on the 3mm layer, 16.5% higher on the 6mm layer, and 8.5% higher on the 9mm layer, respectively. The sealing capacity of the ultrasonic scalpels has been investigated through the coagulation dissection experiment on the chicken carotid and their burst pressure tests. The average burst pressure of the sealed vessels by the hemostatic-enhanced ultrasonic scalpel can achieve higher values than that of the conventional ultrasonic scalpel.