The Simulation Design And Fabrication Of Intravenous Ultrasound Transducer

Intravascular ultrasound (IVUS) is a new kind of minimally invasive diagnostic methods.This method can accurately grasp the blood vessel wall form and its narrowness and is of highdiagnostical value in the interventional diagnosis and treatment for coronary heart disease. Asthe most critical part in the IVUS system, IVUS transducer which is of small volume, highfrequency, high resolution, is widely used in the diagnosis and treatment for cardiovasculardisease and high quality, high resolution image can be obtained.IVUS ultrasonic transducer consists of piezo disc, matching layer(s), electrode andbacking etc. The thickness of each component which determines the performance of a IVUStransducer is very important in the process of manufacturing. Using the finite element method(FEM) to simulate the thickness effect on each component can provides valuable guidanceinformation to optimize the IVUS design and manufacturing process.In this paper, chapter1gives the overview of IVUS and IVUS transducer; Chapter2introduces the fundamental acoustic theory, general design method of IVUS transducer and itsfinite element simulation method. Chapter3analyzes the vibration of the transducer underdifferent conditions, the performance of the transducer at different parameters is compared.Corresponding to the chapter3, chapter4analyzes the transducer’s sound field under differentconditions and compares the transducer’s sound field at different parameters. Chapter5focuses on the analysis of the transient response of the transducer at different parameters andthe results are compared with actual sample. According to the simulation and practical test,we can find: the40μm piezo disc has a resonant frequency of near50MHz, which issuitable to the IVUS transducer whose working frequency is designed as50MHz. And underthe50MHz electrical excitation, the vibration of piezo disc consists at least thickness vibration mode and radial radiation mode, etc.; And the addition of matching layer canintroduced other resonant frequencies on the admittance curve and great interference on theresonant frequency, anti-resonant frequency of IVUS transducer, especially the influence ofthe second matching layer; The sound field results show that the matching layer(s) canimprove the efficiency of ultrasonic transmission effectively and then improve the intensity ofthe sound field; Adding the backing layer can improve the properties of sound field andsomehow improved the admittance curve, but the change of the backing layer’s thickness haslittle effect on the transmitted sound field; By comparing the results at different parameters,the optimized thickness of piezo disc, the first match layer, the second match layer and thebacking layer is40μm,13.5μm,11μm,160μm; Based on the transient response analysis andits results, we can notice that the simulation analysis has high coincidence with theexperimental results.The results above show that using the finite element method to optimize the design andmanufacturing of IVUS is feasible and effective. Such method can shorten the time of designand manufacturing of IVUS and save the cost.