PIEZOELECTRIC POLYMER COMPOSITE ARRAYS FOR ULTRASONIC MEDICAL IMAGING APPLICATIONS

The predominant sensor materials used in medical acoustic imaging have traditionally been piezoelectric ceramics (PZT, LaNbO3, etc.) More recently piezoelectric polymers (PVDF) have been used in this area. Polymers present several advantages over ceramics (very flexible, easy to process, good acoustic matching to tissue, good reception constant), but also have some major drawbacks (poor emission constant, low coupling coefficient). Composite piezoelectric materials aim to incorporate the most advantageous properties of ceramics and polymers. This paper investigates the electrical and mechanical properties of two different piezoelectric polymer composite materials (Piezoflex1 and Piezel) to assess their performance for medical imaging applications. Practical transducer constructions with corona-poled, PCB-backed and diced-array architectures have been manufactured with the composites, and their performance evaluated in pulse-echo mode. The results obtained, using a simple object as target, confirm the potential use of the composite materials in medical imaging applications.