The goal of this program is to apply recent advancements in the growth of piezoelectric single crystal materials to build ultrasound transducers with very broad bandwidth, which can improve and simplify ultrasound imaging for combat casualty care. Relaxor-based ferroelectric materials of PZN-PT and PMN-PT have been shown to have coupling factors for some modes of over 90%. Transducer modeling shows that these properties can theoretically lead to transducers with exceptionally wide bandwidth (over 120%). The set of procedures which would be useful for external imaging during triage in a combat casualty care would take up to three transducers of standard construction ranging from 3.5 MHZ to 7.5 MHZ in center frequency. If a transducer with 120% bandwidth can be constructed, that single transducer can perform all of those imaging functions. Tetrad will work with TRS Ceramics and Crystal Associates who are the leading U.S. manufacturers of high-coupling single crystal material. In Phase I, methods for surface preparation, grinding, metalizing for electrode attachment, bonding of polymers, and processes for building 2-2 and 1-3 composite materials will be investigated. Samples of these materials will be used to build subapertures of medical imaging arrays demonstrating broad bandwidth in the water tank. The goals for Phase II will be to use these designs and production methods to develop complete 1-D and 1.5-D ultrasound imaging arrays and to show images covering the bandwidth achieved.
