Reseachers at the University of California and InvenSense developed an 20 MHz ultrasound imager based on a piezoelectric micromachined ultrasonic transducer (PMUT) array having integrated acoustic waveguides. The imager consists of a PMUT array bonded with a CMOS ASIC using wafer-level Al-Ge eutectic bonding.
- Y. Lu, H. Tang, Q. Wang, S. Fung, J. M. Tsai, M. Daneman, B. E. Boser, and D. A. Horsley, “Waveguide piezoelectric micromachined ultrasonic transducer array for short-range pulse-echo imaging,” Applied Physics Letters, vol. 106, no. 19, p. 193506, May 2015. Available: http://dx.doi.org/10.1063/1.4921346