“…Piezoelectric material-based NGs may play an important role because they can scavenge mechanical energy and transform it into a more flexible form, such as electrical energy. To date, piezoelectric materials based on PZT (lead zirconate titanate) [1][2][3], BaTiO 3 [4,5], polyvinylidene difluoride (PVDF) [6,7], BNT (bismuth sodium titanate) [8], and zinc oxide (ZnO) [9][10][11][12][13][14][15][16][17][18][19][20] have been the most widely investigated ones for use in transducers, actuators, transformers, photonics, optoelectronics, and sensors. However, fiber-based piezoelectric NGs [21][22][23] have not been extensively developed for keyboards because they must be resistant to large mechanical loads.…”