The Design Methods And Experiment Research Of Ultrasonic Scalpel With Minimal Invasive Single-hole

Ultrasonic scalpel is a surgical instrument that can be used to cut and separate tissues with high frequency vibration.It has many advantages such as high precision,edge neat and quick hemostasis,small thermal damage area,producing less smoke and so on,then it has been widely used in modern surgery recently.But the ultrasonic scalpel has low output efficiency and poor stability in practical application,and the interaction mechanism between ultrasonic scalpel and biological tissue is not understood very clear.It has high social value and economic benefits for studying the ultrasonic surgical technology and theory to develop a new ultrasonic scalpel system to meet the requirements of minimally invasive surgery of single hole.Therefore,the interaction mechanism between ultrasonic scalpel and biological tissues is studied theoretically and experimentally,and the ultrasonic scalpel for minimally invasive surgery of single hole is designed based on the theory of the phonon crystal in our research.The main contents in this thesis are as follows:1.Based on Hertz contact theory,the interaction model between the ultrasonic scalpel and biological tissue is established.When the ultrasonic scalpel is applied by the normal static load and harmonic force,and the strain field in the tissue is solved by Hankel integral transformation,respectively.The relationship between the load force F--indentation depth ? and the Young's modulus E is found,and the effect of tissue elasticity on resonance frequency of indenter is discussed.It provides an important theoretical basis for the experimental research of the interaction between ultrasonic scalpel and biological tissue.In order to optimize the structure of ultrasonic surgical scalpel and prolong the service life,the fatigue characteristic of ultrasonic scalpel is explored preliminarily.2.The ultrasonic scalpel is designed based on the phononic crystal theory.Using the lumped mass method and transfer matrix method,the band gap structures of the longitudinal and flexural waves in the long rod with variable cross section are calculated respectively,and the geometrical parameters of ultrasonic scalpel are determined.The band gap characteristics of a slender rod with finite periods are simulated and calculated by the finite element method.By adjusting the geometric parameter of scalpel,the bending vibration mode around 55 KHz of the scalpel is located in the gap band and depressed,and its longitudinal vibration mode at 55 KHz is located in the pass band and transmitted.The buckling coupling structure of the ultrasonic scalpel cutting head is also designed and optimized.3.A new push-pull exciting ultrasonic transducer is proposed and an ultrasonic scalpel driving system with frequency automatic tracking and constant amplitude is designed.A novel ultrasonic scalpel system is established.It operated around 55 KHz and the vibration modes and amplitudes of the scalpel are measured.It shows the amplitude at scalpel head can be obtained in the range of 50 to 100 ?m.Then according to the general industry standard yyt0644-2008,the technical parameters of the prototype of ultrasonic scalpel driving system are verified.4.An elastometer for biological tissues is set up.And an experimental system for measuring the ultrasonic scalpel's cutting rate and temperature distribution in the tissues is also established.The Young's modulus of the pork,beef,liver and kidney and other tissues are measured,and the ultrasonic scalpel cutting rate and the temperature distribution in sample around the scalpel head are investigated in order to assess the effects of scalpel cutting rates on hemostatic function and tissue damage degree.