INTEGRATED SILICON-PVF2 ACOUSTIC TRANSDUCER ARRAYS

A new type of transducer array has been designed which employs a piezoelectric polymer, polyvinylidene fluoride (PVF2), as the sensing material. Acoustic properties possessed by this piezoelectric polymer provide a reasonable match to those of the human body making it very attractive for medical ultrasonic imaging systems. Using planar integated-circuit (IC) technology, an array of MOSFET input amplifiers is fabricated on a silicon wafer. A single sheet of PVF2 is bonded to the surface of the wafer. Spatially varying acoustic signals detected by the PVF2 are converted to corresponding charge distributions on the underlying array of amplifiers. A linear 34-element receiving transducer array has been built and evaluated. Array transverse dimensions are 14.7 × 9 mm, so that the silicon die area is approximately 1.32 cm2. Individual transducers are 0.42 × 9 mm corresponding to the requirements of a particular system. Associated with each of the 34 transducers is a DMOS-bipolar cascode amplifier. Experimentally measured transducer impulse response decays 20 dB in two cycles. Using silicon technology, arrays of almost arbitrary size and complexity appear feasible. Copyright © 1979 by The Institute of Electrical and Electronics Engineers, Inc.