High frequency piezo-composite transducer array designed for ultrasound scanning applications

A 20 MHz high density linear array transducer is presented in this paper, This array has been developed using an optimized ceramic-polymer composite material. The electro-mechanical behaviour of this composite, especially designed for high frequency applications, is characterised and the results are compared to theoretical predictions. To support this project, a new method of transducer simulation has been implemented. This simulation software takes into account the elementary boundary phenomena and allows prediction of inter-element coupling modes in the array. The model also yields realistic computed impulse responses of transducers, A miniature test device and water tank have been constructed to perform elementary acoustic beam pattern measurements. It is equipped with highly accurate motion controls and a specific needle-shaped target has been developed. The smallest displacement available in the three main axes of this system is 10 microns. The manufacturing of the array transducer has involved high precision dicing and micro interconnection techniques. The flexibility of the material provides us with the possibility of curving and focusing the array transducer. Performance of this experimental array are discussed and compared to the theoretical predictions. The results demonstrate that such array transducers will allow high quality near field imaging. This work presents the efforts to extend the well known advantages of composite piezoelectric transducers to previously unattainable frequencies.