Investigation of the beam pattern of an integrated 2D CMUT spiral array element

This work reports on the investigation of the element beam pattern of a 2D CMUT spiral array by finite element analysis, aiming at assessing the effect of the transducer integration with the ASIC on the fluid-coupled transmission performance. The array element acoustic directivity is computed for the clamped substrate condition and compared with that obtained by coupling the transducer with a Benzocyclobutene (BCB) layer, used as an underfill between the CMUT and the ASIC. Different packaging solutions are considered and their effect on the element directivity is compared. The CMUT spiral array element is experimentally characterized in water-coupled transmission operation using a hydrophone to validate the finite element simulation.