A Low Power Image Reconstruction Technique for Phased Array Scanners

Abstract

Traditionally, medical ultrasound array transducers have used piezoelectric ceramics as their active elements. This technology has been very successfully developed over the years and current medical scanners produce very good images of large structures within the body. For peripheral structures (small parts scanning) higher frequencies can be employed to improve the resolution, but the constructional methods used with piezoelectric ceramic materials limit the width of array elements to about 0.1 mm. This corresponds to a centre frequency of about 7.5 MHz. The decision was therefore taken that the active element for our high frequency array research programme should be one of the piezoelectric polymer materials. Poled polyvinylidene fluoride1 (PVDF) and its copolymers are readily available from a number of suppliers worldwide, but in addition the research group has a long experience of manufacturing the copolymer of vinylidene fluoride and trifluoroethylene (VDF-TrFE) and using it in a variety of devices².