Kinetic motion sensors based on flexible and lead-free hybrid piezoelectric composite energy harvesters with nanowires-embedded electrodes for detecting articular movements

Self-powered motion sensors have drawn many attentions for the last decade because it can be usefully applied to not only smart clothing and biomedical applications but also future remote controlling robotics systems. In this study, we develop a ceramic–polymer hybrid lead-free piezoelectric composite-based device to fabricate excellent flexible energy harvesters and kinetic motion sensing gloves. With the use of a composite composed of (K,Na)NbO₃ (KNN) piezoelectric particles and poly(vinylidene fluoride-trifluoroethylene) [P(VDF-TrFE)] matrix, the fabricated flexible energy harvester generates an open-circuit voltage of ~5 V and short-circuit current of ~1 μA under mechanical bending deformations. Moreover, the advantages of the P(VDF-TrFE) matrix for piezoelectric composite-based devices are validated by the results of the finite element method (FEM) simulation. Based on the hybrid piezoelectric composite, stable and reliable self-powered kinetic motion sensors are fabricated to monitor tiny biomechanical motions, i.e., the angles of finger hinges and various hand gestures. Our development successfully indicates that the hybrid lead-free piezoelectric composite can be applied to the active component of self-powered kinetic sensors for future low-power electronic motion detector.