Fundamental Study on Vibration in Edge Face of Piezoelectric Chiral Polymer Film

We evaluate the vibration in the edge face of a poly(L-lactic acid) (PLLA) film from the propagated signal of an ultrasonic wave generated by the excitation force of the edge. Although the excitation area is too small to drive the edge face, the vibration can be measured only using the fixing method that does not suppress the resonance and the equipment with a high signal-to-noise ratio. This is considered to be due to the fact that the theoretically calculated force of the PLLA film is more than 10 times larger than that of a well-known ferroelectric polymer film, poly(vinylidene fluoride). We confirm that the film functions as a resonator and can be applied to a resonated transducer. In spite of the vibration in the edge face of the polymer film, we observe compliant responses to excitations by burst or rectangular waves. The practicality of a resonator can be suggested. (C) 2013 The Japan Society of Applied Physics