Miniature Highly Sensitive Ultrasound Doppler Transducers

Abstract

The ultrasound transducer is considered a critical and important part of any ultrasonic measurement system. The transducer is the part of the system that transmits and receives soundwaves by converting electrical energy into acoustic energy and vice versa. The study in this thesis mainly focused on the development of single element transducers. Transducers were designed, fabricated and characterized. Mid-frequency, 6 MHz, single element transducers were fabricated at the HSN Ultrasound Laboratory. Highfrequency, 20 MHz single element transducers were fabricated in the Biomedical Research Center at University of Southern California. Transducers were simulated in onedimensional circuit models and finite element models for comparison and evaluation of results. Fabricated transducers were characterized by electrical impedance measurements, pulse-echo measurements and beam profile measurements.

Fabrication steps for mid- and high-frequency transducers have been discussed in detail. New and common fabrication designs have been presented where the main optimization factor has been on sensitivity. High sensitivity transducers with a broad bandwidth could find applications in Doppler measurements and Pulse-echo imaging.