SOLEF® PVDP biaxially oriented piezo- and pyro-electric films for transducers

Abstract

Previous work has shown that biaxially oriented PVDF, which is subsequently poled by means of corona discharge, gives piezo- and pyro-electric films with improved physical and piezoelectric properties. These has confirmed that the choices of base material, β-transformation and polarization conditions are important factors for the optimization of film quality. SOLEF® biaxially oriented film, made by a proprietary extrusion process and continuously poled at 5 – 20 MV per cm, has definite advantages over the monoaxially oriented competitive products: long-term exposure up to 90 °C shows the product to be stable after an initial loss of the d 33 piezoelectric constant of the order of 15 percent. Variations of the d 33 constant over the surface are within 10 percent. Cost of the continuously poled film for the first time is in a range suggesting new end uses, where large surface area sensor arrays and/or large volume applications such as those required for electric energy generators can become economically viable. Improved methods of adhesion of the metal electrode layer to the surface of the film give adhesion strength test, results surpassing those of the standard Scotch tape test. A recent spurt of activity in many transducer applications, as evidenced by the increasing number of publications, suggests that many new applications for this unique material will become a reality. A few actual as well as potential applications are listed, where the advantages of piezoelectric PVDF have been exploited. Undoubtedly each new successful application will in turn spawn ideas for more novel and original applications.