ULTRASONIC TRANSDUCER MATERIALS FOR MEDICAL APPLICATIONS

Ultrasound has surgical, therapeutic and diagnostic applications in medicine. The highest intensities are used in surgery and in physiotherapy, and ceramic transducers with high efficiency and narrow bandwidth are used. For diagnostic purposes, short pulses are often required, and ceramic transducers require careful matching to the load. The ultrasonic beam is focused by lenses or curved transducers, or synthetically by means of arrays. PVF2 is a promising material because of its low characteristic impedance and Q(m), but improvements in coupling coefficient are needed and the low dielectric constant and Q(e) pose formidable problems. Other considerations include those of electrical, biological and acoustical safety.