Row-column addressed 2-D CMUT arrays with integrated apodization

Experimental results from row-column addressed capacitive micromachined ultrasonic transducers (CMUTs) with integrated apodization are presented. The apodization is applied by varying the density of CMUT cells in the array with the objective of damping the edge waves originating from the element ends. Two row-column addressed 32+32 CMUT arrays are produced using a wafer-bonding technique, one with and one without integrated apodization. Hydrophone measurements of the emitted pressure field from the array with integrated apodization show a reduction in edge wave energy of 8.4 dB (85 %) compared to the array without integrated apodization. Field II simulations yield a corresponding reduction of 13.0 dB (95 %). The simulations are able to replicate the measured pressure field, proving the predictability of the technique.