A study of piezoelectric films as sensors for detecting fluctuating area-averaged strain has been conducted. Both theoretical and experimental results on the characterization of piezoelectricity are presented for KYNAR Piezo Films. The theoretical formula relating the in-plane area-averaged strain to the electric output of a piezo film through a charge amplifier was derived, and the relevant constants were determined experimentally. The present results show that if the films are prepared and adhered properly, they can be used satisfactorily for fluctuating strain measurement. The present work has also investigated the possibility of using PVDF films as sensors for monitoring crack growth on a metallic specimen.