DEVELOPMENT OF VHF TRANSDUCERS &ARRAYS

For clinical applications in dermatology, ophthalmology and intravascular imaging, high performance single element transducer and linear arrays have to be developed. Since the piezoelectric elements used in these devices are small, they cannot be fabricated with conventional piezoelectric materials and methods. In this project, single element transducers and linear arrays in the frequency range from 30 to 80 MHz will be developed and tested using an ultrasonic backscatter microscope and a flexible beam forming system which are being developed in parallel with this project. Single element transducers ranging from 20 to 90 MHz have made using modified PT, fine grain PZT, 1-3 fiber composite and PZN-PT and performance assessed. A 48 element linear array at 30 MHz using fine grain PZT is being developed. Initial results show a bandwidth of better than 45% and a cross-talk between adjacent elements of less than -28 dB. Element to element uniformity is better than 20%. These devices will be used to image excised animal tissues and patients with the assistance from the clinicians once the UBM system and the beam former are completely developed and compared to the images obtained by conventional devices. [unreadable]