Novel Micromachined Single Crystal Patterning for Wideband Dermatology Transducer

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DESCRIPTION (provided by applicant): The goal of the proposed research is to develop an extremely broadband, high frequency ultrasound transducer for dermatologic imaging. TRS proposes to make novel, high frequency piezoelectric composites for ultrasound transducers by incorporating multiple piezoelectric modes within a single composite plate. Photolithography will be used to define micron-scale structures and chemical etching will be used to micro- machine the desired transducer pattern. The technology is based on two key concepts: deep reactive ion etching (DRIE) of single crystal piezoelectrics to make very fine scale transducer structures and the large change in frequency constant that occurs as the aspect ratio (height/width) changes. Through non-uniform patterning, multiple modes are present within the plate at different frequencies. The overall bandwidth can surpass that of lower frequency composite transducers and higher frequency polymer transducers. For Phase I TRS will demonstrate a single element, 20-30 MHz transducer with a bandwidth approaching 150%. In Phase II a composite linear array utilizing similar modes will be developed improved imaging performance. Successful completion of this program will produce transducers which have the flexibility to provide both high resolution as well as improved depth of penetration, decreasing scan time, and allowing for improved Doppler performance in small vessels. The technology will improve the performance of dermatologic ultrasound and help make ultrasound more clinically relevant for dermatology applications such as melanoma and psoriasis characterization, radiation-induced fibrosis and wound healing.