The objective of our research is to develop an ultrasonic transducer technology which will increase the bandwidth of medical arrays to two octaves or more while maintaining high transduction efficiency. This technology is based on asymmetric, multilayer piezoelectric layers and multiple matching layers. In particular, one class of asymmetrical structures, consisting of unequal thickness, two layer piezoelectric ceramic with three matching layers, will be the focus of this research. The efficacy of many present and future medical ultrasonic imaging applications would be greatly enhanced with ultra-wide bandwidth capability, such as harmonic imaging and image guided therapy. We have chosen to build a device supporting an innovative scheme, conceived at the University of Michigan, to use a ultra-wideband, low frequency pumping pulse to enhance the contrast of images made in real-time by a wideband, high frequency imaging array. We will conduct extensive finite element simulations in order to optimize the design of the 1 MHz pump array, develop more powerful simulation tools in order to conduct virtual prototyping of the complex structure, and then design, construct, and test the array. The much smaller imaging array will be mounted in the center of the pump array. System tests of the device will be carried out at the end of the project.
