Shingo Kaimori

Piezoelectricity of fluorine-system porous electret and its application

We developed a piezoelectric polymer film that was an electret using a porous poly(tetrafluoroethylene) (p-PTFE) film with high piezoelectricity and high heat resistance. First, we found that the p-PTFE electret had a piezoelectric constant d33 of 100 pC/N after the optimization of its pore size. This value was about five times as large as that of poly(vinylidene fluoride) (PVDF) and was retained up to a temperature of as high as 120 °C. Then a new device using the laminated film with perfluoroalkoxy (PFA) laminated on one side of the p-PTFE electret was developed for the demonstration of pressure sensing. A new flexible device with a large area was realized. Then, for the demonstration of pressure sensing, a plastic touch pen for a touch panel was traced on the surface of the device at a constant speed of 80 mm/s under a compressive load of 0.05 N. The results confirmed that the device exhibited superior sensing responsiveness.