Auxetic Structured Silver Nanowire-PVDF Nanocomposite Piezoelectric Nanogenerators for Self-Powered Wireless Wearable Sensing

Developing piezoelectric nanogenerators that function effectively in the d31 mode is particularly important for wearable biosensing, where mechanical forces are applied perpendicular to the poling direction. In this work, we introduce an energy-harvesting platform that combines an AgNWs/PVDF nanocomposite with auxetic structures (negative Poisson’s ratio) produced through material extrusion. The elliptical and kirigami designs provide exceptional stretchability, allowing the structures to deform more uniformly and generate higher local strain, which in turn increases charge production. The device output was further boosted by corona poling to align dipoles and by using a direct ink writing (DIW) printed conductive electrode to improve charge collection. Experimental measurements together with simulation studies reveal that the elliptical auxetic PENGs, operating in the 3–1 mode, undergo larger strain amplification and deliver significantly improved output reaching 5.2 V, 1.2 μA, and a power density of 0.5 W·m–2, nearly four times higher than their nonauxetic counterparts. These optimized devices show stable operation under various biomechanical deformations and effectively harvest energy from routine human motion. With the addition of a wireless transmission module, the system is also capable of real-time monitoring of physiological signals, highlighting the potential of auxetic-engineered PENGs for next-generation self-powered wearables and wireless health-monitoring technologies.