Development of PZT-based ultrasonic concave diaphragm transducer with engineerable acoustic beam focal range

A novel PZT-made ultrasonic concave diaphragm transducer is designed, fabricated, and tested. The developed piezoelectric transducer can generate high-frequency self-focused acoustic beam. The unique characteristics of the device include (1) ~ 50 micron thick PZT film is fabricated on an innovative flexible substrate, which can release and adjust the induced residue stress during PZT deposition to avoid crack generation and maintain good piezoelectric structure and quality (2) Utilizing the novel curvature shaping technique to define the focal ratio of the transducer so the focal range of the acoustic beam generated by the transducer can be engineered. (3) The developed fabrication process allows batch production of the transducer array with low-cost and reliable properties. Detailed proof of concept and testing results are described in the text.