Micromachined ferroelectric transducers for acoustic imaging

Sub-millimeter-sized ferroelectric monomorph sonar transducers have been built using sol-gel PZT on micromachined silicon wafers. 8 X 8 transducer arrays have been tested in water in the frequency range of 0.3 to 2 MHz. An improved sol-gel process has yielded crack-free PZT films up to 12 mu m in thickness, 12 X thicker than previously reported. Sensitivity, frequency response, acoustic images and beam patterns are presented. High-resolution acoustic images at a range of 2 m were made using the arrays and an acoustic lens. Applications include high-frequency imaging sonars, medical ultrasound, ultrasonic communication links, and flaw detection.