Used In Medical Ultrasound Imaging Systems, The New 1-3 Lead-free Piezoelectric Composite Materials Research

Medical ultrasonic technology becomes the irreplaceable pillar in medical image technology because of it's' excellences such as non-ionization radiation, low cost, good distinguishing ability to the soft tissue and use easiness. In recent years, with the rapid development of the acoustics principle and electronic computer science, ultrasonic image technology has been improved greatly and become an essential one and even a first-selected method in clinical diagnosis. In the ultrasonic diagnostic device, the transducer is a part of ultrasound transmission and echo receiver, which is the most important acoustics part and affects the imaging quality directly. So, according to the development trend of medical ultrasonic, the high-performance transducer will become the key index to imaging system.Key materials of the medical transducer are basically all 1-3 piezoelectric composites at present. The piezoelectric composite is the result that the piezoelectric ceramic and the piezopolymer combined together according to a certain way which collects advantages of both the piezoelectric ceramic and the piezopolymer in one suit. But this kind of materials are mostly leaded composites at present, and will bring the injury to the environment and the mankind in using course, production process and treatment course after discarding. The research and development of the lead-free piezoelectric composites is in urgent need owing to the restriction of the regulation of environmental protection, social sustainable development and the raise of material serviceability, and it is also one of the important measures in reducing and restraining lead pollution from the source. Some lead-free piezoelectric ceramics have low dielectric constant, high electromechanical coupling constant, high frequency constant, high intensity constant among the existing lead-free piezoelectric composites, but they have some deficiencies in working temperature, stability and structure at the same time. To make up the deficiencies, if compounding the piezoelectric ceramics with the piezopolymers, can forecast new lead-free piezoelectric composites which are suitable for medical ultrasonic transducer, by the excellences of the piezopolymers such as flexility, low ultrasonic impedance and matching easily.Certain difficulties exist in the experimental work as to the lead-free ceramics and lead-free piezoelectric composites of the present stage. We can utilize the finite element method to carry on the theory to calculate to the 1 -3 lead-free piezoelectric composites. Characteristics of piezoelectric composites are related to the characteristics and the proportion of the compounds, connectivity mode, etc. So, studying the factors which can influence composites' characteristics has important actual meanings. Analyze the piezoelectric materials through the large-scale common software ANSYS, using steps such as modeling, defining material properties, meshing, coupling, defining voltage, etc. Analyze the piezoelectric materials through the large-scale common software ANSYS, using steps such as modeling, defining material properties, meshing, coupling, defining voltage, etc. Adopting static and dynamic simulations, we can get performance indexes of 1-3 lead-free piezoelectric composites finally. We get piezoelectric constants, relative dielectric constants, rigidity constants of the composites through static analysis. We also can get electromechanical couple factors, frequencies, and impedances through mode and harmonious wave analysis. On the analytic process, we can receive the performance parameters of different composites under different conditions by changing ceramic content, ceramic space size, ceramic space arrange ways, piezoelectric and non-piezoelectric materials.From the results which are simulated and analyzed through ANSYS can be found that different factors impact on composites differently, but the piezoelectric coefficients of the 1-3 lead-free piezoelectric composites of whole are all high, so are the electromechanical couple coefficients and frequencies. Predicting the feasibility to this brainchild and the applicability of the lead-free piezoelectric composites in medical ultrasonic science that compounded with two kinds of materials given.