SBIR-STTR Award

This proposed research is targeted towards demonstrating the feasibility of constructing ultra-wideband ultrasonic transducers based on asymmetric piezoelectric structures and multiple matching layers. Transducers and arrays based on this technology would enhance medical diagnostic ultrasonic imaging by further enabling the incorporation of wideband signal processing techniques. These techniques, such as harmonic imaging, multimode operation, and chirped or coded excitation, have already begun to make large impact on the imaging industry. Initial simulations of one asymmetric structure has shown that 2 octaves of bandwidth can be achieved with high transduction efficiency. Incorporation of piezocrystal materials promises to extend the bandwidth to 3 octaves or more. This particular structure will be further simulated using 1D and 3D tools to optimize the design, develop general design rules, and evaluate the viability of currently available piezocrystal materials. Prototype transducers will be built, tested, and evaluated for viability in transducer array structures. This technology is expected to be a powerful new tool for enabling enhanced ultrasonic imaging. PROPOSED COMMERCIAL APPLICATIONS: If this technology is successfully demonstrated, many, if not most, commercial arrays would incorporate it into its structure. Over 70,000 new array-based probes are built every year to support the $2.5 billion medical ultrasonic imaging industry.

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.