Mechanism Analysis And Prototype Design Of Ultrasonic Scalpel With Distal Flexible Joint

In robot-assisted minimally invasive surgery(MIS),doctors can easily operate the multi-degrees-of-freedom surgical instruments to complete the complex operation with the help of surgical robot,which has the advantages of convenient operation,high precision,and clear visual field.As a precise and effective surgical tool,ultrasonic scalpel has the advantages of reliable vessel sealing with simultaneous cutting,less thermal damage and smoke,and self-clean.However,the current long,straight,and rigid ultrasonic scalpels have limited degrees of freedom(DOFs)which restricts the operation dexterity of the MIS robot.To address the problem,a multi-DOF ultrasonic scalpel,which is achieved by placing the micro-ultrasonic scalpel at the distal end of the multi-DOF robotic instrument,has been proposed in the paper.Around this topic,the following work have been carried out:First,the initial dimensional parameters of the ultrasonic transducers have been calculated by employing the electromechanical equivalent method and mechanical vibration theory.Then,the dynamic behaviors of the scalpels with different geometry were investigated by using the finite element method(FEM)technique.On the basis of above analysis,the optimized scalpel had been achieved based on response surface optimization method.After that,the designed scalpel prototype was manufactured,and its dynamic characteristics were further researched by using impedance analyzer.The results revealed that the actual features of the transducer coincide well with the result of FEM.And tip amplitude,temperature characteristics and ability of dissection and coagulation of the designed micro-ultrasonic scalpel were further studied using the built experimental platforms.Tip amplitude of the ultrasonic scalpel is approximately 40?m,when it is driven with a sinusoidal voltage of ±30V at its resonant frequency.The ex vitro experiments showed that the amplitude and the frequency of the vibration could fulfill the requirements of dissection and coagulation of tissues.Finally,a 4DOFs wrist-like structure used for mounting the developed microultrasonic scalpel was developed,and its dynamic characteristic and kinematics were analyzed in detail.