| Nine polyvinylidene fluoride (PVDF) membrane transducers were developed to be used as receivers and transmitters in underwater applications, such as in acoustic reflectometry. The design requirements were oriented to comply with a bandwidth of 10 to 160 kHz, minimize the transducer size and generate construction techniques that will allow future researchers to modify the transducers and adapt them to different geometries. They represent a novel concept because of their working frequency range and their physical construction, easily shaped to customized applications. The nine transducers were created through the combination of three different PVDF film thicknesses (28, 52 and 110 mum) and three circular active areas (with radius 2, 3 and 4 mm). The receiving and transmitting sensitivities were studied through computer simulations and experimental tests, with respect to three main parameters: frequency, active area and film thickness. The receiving sensitivity increased as function of active area, and did not reveal any clear trend with respect to thickness or frequency. The transmitting sensitivity increased its magnitude with increasing frequency or the active area, but did not depend considerably on thickness. The final construction technique selected was to attach the PVDF film to a pre-engraved conductive base, with a case molded with an epoxy material. It offers the most advantages because the electrodes connection does not affect the piezofilm physical properties and the case can be easily shaped. |
