By Gary Thomas
Teijin, the company specializing in high performance fibers and Kansai University in Japan have jointly developed a new piezoelectric material derived from polylactic acid that exhibits exceptional piezoelectric properties.
The new piezolectric material
The transparent, flexible material is the result of collaboration between the New Films Development Division of Tejin and Professor Yoshiro Tajitsu from Kansai University’s Faculty of Engineering Science.
Piezoelectric effect is the phenomenon observed in certain materials in which strain generated by application of pressure is converted into proportional electric power. Such materials usually find application in vibration or impact sensors. The inverse piezoelectric effect, which is the reverse phenomenon in which applied electric power generates distortion, is employed in ultrasonic transducers, amplifiers and actuators. Lead zirconate titanate (PZT) is the most commonly used piezoelectric material. The new material supersedes PZT in terms of piezoelectric performance and apart from being environmentally friendly, could be the basis for the development of bigger, lightweight devices previously difficult to devise. The manufacturing method for the new material involves simple coextrusion technique that involves alternating lamination of films of two types of polylactic acid, namely, optical isomer poly-D-lactic acid (PDLA) and poly-L-lactic acid (PLLA). The piezoelectric motions demonstrated by the PDLA and PLLA films when subject to electric fields of the same orientation are in opposite directions. Aligning the two piezoelectric motions in the same direction is achieved by introducing alternate positive and negative electrodes between the two types of films. Research revealed that piezoelectricity of the new material is enhanced drastically with level of material purity. The material has the distinction of being the world’s first multilayer, binary blended PLA film demonstrating excellent piezoelectric effects.