A 3 MHz two dimensional array based on piezocomposite for medical imaging

2-D array transducers present a major interest for ultrasound volumetric imaging as they allow data acquisition and visualization in real time. However their manufacture remains a technological challenge because of the very high number of elements with reduced lateral dimensions close to a half wavelength pitch. During this work, we developed and set up an industrial process to manufacture fully connected array through an innovative rear material, combining the backing function and the high density interconnect. This process does not affect the acoustical behavior of each elements and the connection of all elements is performed in a single operation. In addition, for the acoustical design, specific backing and matching layers structure have been implemented to reduce cross-talk and to increase the acceptance angle. A 2D fully populated array, based on this design, with a 3 MHz center frequency, 300 microns pitch, containing, 4096 elements (64×64) is presented. The evaluation of the performances over the array includes electroacoustical characterizations (pulse echo waveforms and spectrum), electrical measurements (electrical impedance and cross-talk) and acceptance angle data, obtained by hydrophone setup techniques. This design can be applied to many configurations, over a wide range of pitch and frequency, from fully populated to sparse array.