Design and Optimization of a High Performance Ultrasound Imaging Probe Through FEM and KLM Models

The design and optimization of high performance ultrasound imaging probes often needs a reliable model to provide performance estimates related to project upgrades. Finite Element Model (FEM) is the most powerful and comprehensive tool available for this application, but needs a very fine preliminary tuning procedure in order to obtain consistent results. This was described in our previous work [1], where we considered a simple disk transducer layout and outlined an appropriate model optimization procedure. The present work takes a step forward, approaching the development of a full FEM model for linear array high performance ultrasound transducer, consisting of 144 piezo– elements, with array pitch as low as 245 μm. The large number of parameters that need to be determined to model the array transducer led us to consider a preliminary design procedure, before getting into the FEM development. The simplified model of the transducer consists in a mono dimensional electro– acoustical KLM model, along with an equivalent transmission line for the “matching layers”, that proved to be a very useful design tool. Once the starting values for the principal parameters of the transducer were calculated, the FEM was developed and optimized. Eventually the optimized transducer was manufactured, so that agreement between transducer measured performances and simulation results were checked and both KLM and FEM models were validated. The results presented here show that the optimized model predicts measurement results in term of electrical impedance magnitude and emitted sound pressure level frequency response. Moreover, the FEM allows to simulate the important properties of directivity and beam steering capability of the transducer, and their dependency on materials‟ parameters can be analyzed.