The use of piezoelectric materials was their original innovation, and it allowed them to simultaneously measure the flexing and the rotation of the teeter - totter beam. (sciencedaily.com)
Each cell has six or eight small holes through which rounded pins can extend and retract with the help of piezoelectric ceramic actuators to represent various Braille characters. (scientificamerican.com)
There's no earpiece as well, so if you're one to take calls, you'll have to rely on cantilever piezoelectric ceramic acoustic technology, which transmits sound without the need for a receiver. (androidcentral.com)