Study On Effect Of Ultrasonic Vibration On Frictional Characteristics Between Needle And Tissue In Soft Tissue Puncture Process

In recent years,malignant tumors have become the number one killer that threatens the health and safety of Chinese residents.The accurate diagnosis of malignant tumors plays an important role in prevention and early treatment.At present,there are a variety of the tumor detection methods,such as nanometer detection and blood chip detection,but the final diagnosis of the tumor is the cytopathology analysis,that is,remove the suspected lesions for cytopathology diagnosis whether it is a malignant tumor.Surgical sampling method causes big trauma,high cost,and sometimes limited by the patient's physical condition cannot be implemented.Compared with the surgical method,biopsy puncture sampling causes small trauma,and easy to operate,heal fast,fewer secondary complications.However,although biopsy puncture has many advantages,it requires extremely high technical level of the medical staff.In addition,the current biopsy sampling device lags behind,resulting in the low efficiency and precision of biopsy sampling.The main reasons for the low efficiency and accuracy of biopsy are the tissue deformation and the bending deformation of the biopsy needle caused by the cutting resistance and friction during the sampling process,Therefore,reducing the cutting resistance and friction during the puncture will effectively improve the biopsy sampling accuracy and efficiency.In this paper,the friction force in the ultrasonic vibration-assisted tissue sampling process is taken as the research object,and the influence of ultrasonic vibration on the friction of the sampling process and the measures to reduce the friction force are investigated.The research results are of great significance for improving the efficiency and accuracy of the biopsy.In this paper,the basic theoretical knowledge of ultrasonic vibration and tribology is briefly introduced,and three kinds of dynamic friction models are emphatically introduced.The dynamic friction model of ultrasonic vibration is obtained by introducing ultrasonic vibration into LuGre dynamic friction model and theoretical deduction.The dynamic friction model shows that the frictional force decreases with the increase of ultrasonic vibration frequency and amplitude.The ultrasonic vibration reduce the Coulomb friction in the puncture process,but has no effect on the viscous force.The friction in the puncture process is correlated with velocity,the velocity increases,and the friction increases linearly.The kinematics theory analysis of the puncture process without vibration and additional ultrasonic vibration is carried out.The results of theoretical analysis show that the biopsy needle does not have a regressive phenomenon in the puncture process without vibration.Additional ultrasonic vibration,when the feed speed is smaller than the ultrasonic vibration speed,the biopsy needle in the puncture process will produce the regression phenomenon.Self-designed and manufactured ultrasonic vibration system.The actual relationship between the amplitude and voltage of each frequency vibrator is measured experimentally,and the amplitude-voltage curve is plotted.The relation curve shows that the amplitude of different frequency vibrator increases linearly with the voltage,and the increase rate decreases with increasing frequency.An experimental bench was set up and an ultrasonic vibrator holding device and angle adjustment device were designed.The experimental feeding system and data acquisition system were designed.The effect of ultrasonic vibration amplitude on the friction force during puncture were verified by single factor experiment with pork liver and gelatin phantom as experimental materials.The experimental results show that the ultrasonic vibration amplitude has the same effect on the fresh pork liver and gelatin phantom,that is,the friction in the puncture process decreases with the increase of the amplitude in the form of exponential power function with the index of-1.The correctness of the theoretical model deduced in chapter two is verified.The effect of ultrasonic vibration frequency on the friction during the biopsy procedure was studied with pork liver and gelatin phantom as experimental subjects.The similar experimental results are obtained for the two materials,namely:the friction force is greatly reduced after additional ultrasonic vibration,and the friction force is reduced slowly with increasing vibration frequency.The friction force and vibration frequency curve is obtained by fitting the friction data of the puncture process.The relationship curve shows that the friction force of the puncturing process decreases with the increase of the frequency in the form of exponential negative power function.The experimental results of the effect of ultrasonic vibration on the friction during the puncturing process are consistent with the theoretical analysis.The effect of the puncture speed on the frictional force during the ultrasonic vibration assisted puncture was studied through design experiments.The relationship curve of friction and velocity was plotted by using the Origin software to process the experimental data,and the relationship curve shows,whether the ultrasonic vibration was added,the friction force during the puncture process increases linearly with the increase of the puncture speed.When the ultrasonic vibration frequency is 30 KHz,the increasing speed of friction decreases with the increase of the amplitude.The ultrasonic vibration frequency 40 KHz has the same rule as 30 KHz.The effects of ultrasonic vibration frequency,amplitude and puncture speed on the friction force during puncture were validated by orthogonal experiment with liver and gelatin phantom as experimental materials.The experimental data were analyzed using the tabulation range analysis method and the software Minitab range analysis method.The same analysis results were obtained with pork liver and gelatin phantom as experimental materials,the friction force decreases with the increase of the vibration frequency and amplitude,and increases with the increase of the puncture speed.The puncture speed has the greatest influence on the friction force during the puncture process,and the amplitude is the second,and the vibration frequency has the smallest influence,thus the optimal parameter combination of the minimum friction force for the vibration assisted puncture process is the minimum puncture speed,maximum amplitude and maximum vibration frequency.