Teijin Limited and Kansai University announced recently that Teijin’s New Films Development Section and Professor Yoshiro Tajitsu, Faculty of Engineering Science, Kansai University, have developed a flexible, transparent piezoelectric material that demonstrates unprecedented piezoelectric effects. The piezoelectric effect is the generation of electric power in proportion to the strain produced when pressure is applied to certain materials, used in impact/vibration sensors. The inverse piezoelectric effect is the distortion caused by applying electric power, used in audio speakers, ultrasonic transducers and other actuators that convert electric energy into motion.
The new material is made with a simple manufacturing process that alternately laminates two types of environmentally friendly polylactic acid (PLA) films: poly-L-lactic acid (PLLA) and optical isomer poly-D-lactic acid (PDLA). According to Teijin, it is the world’s first binary-blended PLA multilayer film with piezoelectric performance that surpasses that of lead zirconate titanate (PZT), a conventional and widely used piezoelectric material, paving ways for larger and more lightweight products that have been difficult to achieve.
The collaboration will continue joint research and development aimed at achieving a wide range of applications, such as sensors that can detect pressure, vibration and impact, as well as ultrasonic motors, ultrasonic transducers for medical care and actuators used in devices such as speakers. The new material can be manufactured with a simple and practical co-extrusion method, introduces Teijin.
By alternately inserting positive and negative electrodes between PLLA and PDLA films, which exhibit piezoelectricity motion in opposite directions when exposed to electric fields of the same direction, the piezoelectricity motion can be aligned in the same direction. Piezoelectric performance can be controlled by varying the number of layers, enabling customized designs to suit specific needs.
Research by Prof Tajitsu revealed that when PLA exceeds a certain level of purity, piezoelectricity improves dramatically. By using high-purity PLLA and PLDA achieved with Teijin’s advanced PLA refining technology, the new multilayer film is said to demonstrate superior piezoelectric performance.