Development of P(VDF-TrFE) ultrasonic transducers operating at 50-120 MHz

Performance of polymer ultrasonic transducers depends greatly oil fabrication methods at frequencies above 50 MHz. Focused poly(vinylidene fluoride-trifluorethylene) [P(VDF-TrFE)] single element transducers in the range of 50-120 MHz and of f-numbers less than 3 were developed using various techniques. A 3 mm 45 MHz transducer was fabricated by spin-coating copolymer directly onto a spherically shaped aluminium substrate. Comparison with a like design press-focused device showed similar bandwidth and center frequency characteristics. Using a conductive carbon backing, the center frequency of a 3 mm transducer was increased by more than 20% over a conventional conductive backing material. A 1.2 mm transducer using a light, nonconductive backing exhibited a 102 MHz center frequency and 35% bandwidth.