Design optimization of ultrasonic transducer element by evolutionary algorithm

Focused ultrasonic wave generation in bio-medical applications depends primarily on the transducer's shape, piezoelectric material and the arrangements of transducer elements over the piston surface for specific power and pulse repetition frequency (PRF). For a given surface area, knowing the relationship between the transducer element's geometry and the generated pressure will be useful for improving the transducer designs. In this study, patterns of pressure field variations with several selected transducer design variables (kerf, transducer element's number and element's width-height) have been investigated. These patterns indicate that there is an optimum shape and arrangement of transducer elements in a given area to achieve highest possible pressure at the focused zone. The number of design variables and their combinations can be used in this case is considerably large, and a Genetic Algorithm (GA) based evolutionary global search method is used to optimize design shape and the distribution of ultrasonic transducer element.