Development of environmentally friendly piezoelectric polymer film actuator having multilayer structure

We designed a new soft piezoelectric polymer actuator with a multilayer structure using the environmentally friendly polymer poly(lactic acid) (PLA). PLA is a chiral polymer having two isomers. One is poly(L-lactide) (PLLA) and the other is poly(D-lactide) (PDLA). PLLA and PDLA exhibit piezoelectric constants with opposite signs owing to their chirality. On the basis of their piezoelectric characteristics, we were able to realize a PDLA and PLLA multilayer film (PDLA/PLLA multilayer) with a simple structure. The PDLA/PLLA multilayer film of centimeter-order size exhibited a large piezoelectric resonance and its piezoelectric performance was equivalent to that of a practical piezoelectric ceramic. In this paper, as a first step toward realizing a new film actuator using the PDLA/PLLA multilayer film, we introduce the piezoelectric characteristics of a PLLA film and the concept of an actuation system using a PLLA film. Next, the fabrication process of the PDLA/PLLA multilayer film and its piezoelectric characteristics are summarized. Finally, typical examples of developed piezoelectric polymer actuation systems using a PDLA/PLLA multilayer film are described to demonstrate the potential application of piezoelectric polymer actuation systems. (C) 2016 The Japan Society of Applied Physics