Electrospinning of Highly Bi-Oriented Flexible Piezoelectric Nanofibers for Anisotropic-Responsive Intelligent Sensing.

Flexible piezoelectric energy harvesters (PEHs) have gained substantial attention owing to their wearability, breathability, and sustainable self-powered supply. However, existing film PEHs cannot identify forces in different bending directions, limiting their applications in wearable electronics and artificial intelligence. This study constructs a fabric PEH for the first time by introducing piezoelectric anisotropic BaTi 2 O 5 nanorods (BT2-nr) into piezoelectric polyvinylidene fluoride (PVDF) nanofibers with a bi-oriented architecture, in which BT2-nr uniformly aligns in the PVDF nanofiber during electrospinning. The dual-orientation feature endows the flexible PEH with anisotropy, which can sensitively identify the forces at different bending directions (e.g., bent vertically, parallelly, or twisted by 45° along the fiber orientations). Simultaneously, the composite PVDF/BT2 PEH containing 15 wt.% BT2-nr delivers an optimal piezoelectric output of 31.2 V with a high sensitivity of 5.22 V N -1 . The developed anisotropic PEH can be used as a self-powered pressure sensor for multimodal intelligent biomonitoring of human movement. This study provides a feasible strategy for fabricating self-powered flexible PEHs with high electromechanical conversion efficiency and multifunctionality for wearable piezoelectric pressure sensors.