Development of a highly attenuative backing for ultrasonic transducers with periodic arrangement of polymeric rods inside the backing

Backings for ultrasonic transducers are generally made of composites of metal or metal oxide powder and epoxy resin or rubber. In this work, a new highly attenuative backing has been developed by installing cylindrical silicone rubber rods periodically inside the two phase mixture. The scattering of ultrasonic waves is dramatically increased by the polymeric rods, which results in big improvement of the attenuation. The silicone rubber rods are molded first, and are disposed periodically on a plane. Then a mixture of epoxy and metallic powder is casted around the rods, and is cured not to have any vacancies. Another backing plate was fabricated as well with the same mixture but without the silicone rods. The backing plates were characterized through ultrasonic pulse-echo tests. Significant improvement of the attenuation has been confirmed through the experiments. Acoustic impedance of the backing can be increased if needed by controlling the volume percent of tungsten powder without causing much variation of the attenuation. This highly attenuative backing is applicable to various size-constrained ultrasound probes like TEE and mechanical 3D transducers.