Cost-effective screen printed linear arrays for medical imaging fabricated using PZT thick films

Screen- and pad-printed single-element ultrasonic transducers have been successfully commercialized over the recent years. Typically, PZT (Lead Zirconate Titanate) thick films are pad- or screen-printed on a curved ceramic substrate acting as integrated backing layer and providing mechanical pre-focus. The center frequency ranges between 8 MHz and 80 MHz. The devices are characterized by good sensitivity as well as high relative bandwidth. The main objective of the presented work has been to apply a similar technology to manufacture multi-element transducers enabling novel cost-effective fabrication of imaging arrays for medical applications. The thick film arrays have been integration-tested using a commercial ultrasound scanner (BK Ultrasound bk3000). The integration test revealed that the 32-element thick film transducers are compatible with a commercial scanner, have a frequency range of 7.5 MHz to 12 MHz, and a TX bandwidth of 70%. Moreover, the transducers support linear array beamforming as well as phased array beamforming. Here 32-element transducers are presented, however the technology can easily be extended to fabrication of transducers with 128 or more elements.