Highly sensitive and omnidirectional anisotropic piezoelectric sensors based on oriented PbZr0.52Ti0.48O3 fibers with intrinsic flexibility

The increasing importance of flexible piezoelectric sensors in the Internet of Things (IoT) is driven by their self-powering capabilities, rapid response times, and high linearity. However, achieving the intrinsic flexibility of inorganic piezoelectric materials to produce highly sensitive flexible piezoelectric sensors remains a challenge. Furthermore, existing piezoelectric sensors remain incapable of distinguishing bending angles in the range of 0–360°. In this work, highly oriented PbZr 0.52 Ti 0.48 O 3 (PZT) fiber films with a bending curvature radius of less than 2 mm were fabricated through electrospinning and optimized sintering process. The flexibility of the PZT fiber films was attributed to the nanoscale ultrafine grains (∼14 nm), which led to stress relaxation at the grain boundaries. The piezoelectric sensor fabricated with these intrinsically flexible PZT fiber films exhibited ultrahigh sensitivity (0.46 V/kPa) and a fast response time (25 ms). The exceptional orientation of the PZT fiber film enhanced the ability of the sensor to recognize deformation angles. By superimposing two fiber films at a 45° angle, the prepared double-layer piezoelectric sensor could detect bending angles over the entire 0–360° range, marking the first achievement of full-angle strain detection in the field of piezoelectric sensors. Finally, a machine learning-based vector recognition system was developed to accurately determine both the magnitude and direction of strain. This work presents a novel strategy for detecting film deformation.