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.
Highlights
Ultrasonic scalpels have been increasingly introduced as a kind of preferred energy-based surgical instrument to perform precise dissection of soft tissues in a variety of clinic procedures [1]–[3]
Zx denotes the equivalent impedances corresponding to each component of the ultrasonic scalpel; U expresses the voltage applied to the scalpel; C0 represents the one-dimensional cut-off capacitance of the piezoelectric ceramic stack; P is the number of the piezoelectric ceramics, and n is the electromechanical coefficient of the ceramics
finite element method (FEM)-BASED DYNAMIC PERFORMANCE INVESTIGATION To validate the proposed enhanced hemostatic scalpel can generate a longitudinal-torsional vibration and radiate more energy than the conventional ultrasonic scalpel, the FEM-based simulation comparisons have been conducted between the ultrasonic scalpels with and without spiral grooves
Summary
Ultrasonic scalpels have been increasingly introduced as a kind of preferred energy-based surgical instrument to perform precise dissection of soft tissues in a variety of clinic procedures [1]–[3]. Using the surgical-grade stainless steel and silicon, Kuang et al [23] developed a new type of ultrasonic scalpel that was configured as a flat shape for the main body and worked with a lateral vibration mode This design suffered from problems in terms of easy cracking under high-stress conditions and significant heat generation phenomena. Based on the above analysis, the mechanical structure of the concentrator on the enhanced hemostatic ultrasonic scalpel has been designed with spiral grooves It can be driven by the piezoelectric ceramics to change the operating mode from the longitudinal vibration to longitudinaltorsional vibration.
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