Passive materials for high-frequency ultrasound transducers

In this paper, the elastic properties of passive materials (matching, backing and lens materials) for ultrasound transducers are explored at room temperature in the frequency range of 25 - 65 MHz using the ultrasonic spectroscopy method. Alumina/EPO-TEK 301 and tungsten/EPO- TEK 301 composites were fabricated and measured. Experimental results display a monotonic rise in acoustic impedance of the composites with the addition of the particle filler. However, there was an attenuation peak occurring at about 8% volume fraction of particle filler. The acoustic impedance of the compositions was modeled. And additional passive materials were fabricated and measured. The measured results showed that materials having high attenuation also had large velocity dispersion, and low attenuation materials displayed low velocity dispersion.