Abstract: A sensor for an ultrasound imaging catheter and methods of fabrication are provided. The sensor may be based on a flex circuit on which a block of piezoelectric sensor array transducer material is mounted. The flex circuit may include electrical conductors that are electrically connected to electrodes on the piezoelectric blocks. A matching layer may be formed on the piezoelectric blocks between the blocks and the flex circuit substrate. Individual transducer array elements may be formed by dividing a piezoelectric block into a plurality of individual transducer elements after the matching layer has been formed. Cuts may be formed in the flex circuit substrate between adjacent transducer array elements to acoustically decouple adjacent elements. The flex circuit substrate and matching layers may have relatively high impedances to facilitate acoustic impedance matching between the sensor and the imaging environment.