Direct piezoelectric responses of soft composite fiber mats

Recently soft fiber mats electrospun from solutions of Barium Titanate (BT) ferroelectric ceramics particles and polylactic acid (PLA) were found to have large (d(33) similar to 1 nm/V) converse piezoelectric signals offering a myriad of applications ranging from active implants to smart textiles. Here, we report direct piezoelectric measurements (electric signals due to mechanical stress) of the BT/PLA composite fiber mats at several BT concentrations. A homemade testing apparatus provided AC stresses in the 50 Hz-1.5 kHz-frequency range. The piezoelectric constant d(33) similar to 0.5 nC/N and the compression modulus Y similar to 10(4)-10(5) Pa found are in agreement with the prior converse piezoelectric and compressibility measurements. Importantly, the direct piezoelectric signal is large enough to power a small LCD by simple finger tapping of a 0.15 mm thick 2-cm(2) area mat. We propose using these mats in active Braille cells and in liquid crystal writing tablets. (C) 2013 AIP Publishing LLC [http://dx.doi.org/10.1063/1.4802593]