Micromachined ultrasonic transducer using piezoelectric PVDF film to measure the mechanical properties of bio cells

We proposed a new method to measure the frequency-dependent attenuation of bio cells using piezoelectric ultrasonic transducer. The polyvinylidene fluoride (PVDF) polymer was employed as piezoelectric material to take an advantage of its low acoustic impedance (2.7 Mrayl) so that the transmission of acoustic power will be improved by impedance matching with that of liquid medium. The thickness of PVDF film is 110 ¿m and the resonance frequency of the 1^st thickness mode is 8.7 MHz. In order to characterize the fabricated ultrasonic transducer, a transducer and an acoustic wave reflector were positioned face to face. The output voltage for reflected transmitted ultrasonic wave was measured with impulse method and was transformed into the Round Trip Insertion Loss (RTIL) where the dominant frequency ranges from 5 MHz to 9 MHz.