Abstract: A transducer apparatus is disclosed having a spool member with a body portion and first and second elevated regions formed on the body portion. A PVDF film surrounds the spool member, the film including an inner surface facing the spool member and an outer surface opposite the inner surface. The film as surrounding the spool member has a predetermined frequency of resonance. Lateral ends of the film are secured together by a securing material. The securing material is such that the secured ends of the film will have substantially the same resonance frequency as a remainder of the film. The film includes a non-electrode area at a perimeter of the inner surface and an electrode material formed on a remainder of the inner surface. Upon securing the lateral edges of the film together, the securement is at overlapping non-electrode lateral edges of the film. The securing material may be any one of an adhesive in combination with screws or thermally deformable nails, adhesive alone, tape, or ultrasonic welding.

Abstract: A transducer apparatus is disclosed including a spool member having a body portion and first and second elevated regions formed on the body portion. A piezoelectric film such as a PVDF film surrounds the spool member and is spaced apart from the body portion of the spool member by an elevation of the elevated region, thereby forming a predetermined gap between the piezoelectric film and the body portion of the spool member. The predetermined gap is at least 0.1 mm and enables a predetermined resonance frequency in the piezoelectric film to control the resonance frequency of the transducer. Opposite lateral ends of the piezoelectric film are secured together such that secured ends of the piezoelectric film have substantially the same resonance frequency as a remainder of the piezoelectric film.