Unraveling the role of interfacial parameters in multifunctional composite nanofibers: Enhancing piezoelectricity, sensing, and energy harvesting

• Interfacial modulus is key to enhancing piezoelectric and sensing performance. • Mechanical strength and output voltage improve by up to 297% and 355.6%, respectively. • High-modulus nanofibers enable sensitive detection of subtle hand gestures. • Piezoelectric output correlates with interface stiffness, not interface thickness. • Interface tailoring offers a strategy for multifunctional wearable energy devices. Composite nanofibres are now widely used in advanced textiles, and their interfacial region plays a decisive role in determining overall material performance. Yet the way in which specific interfacial parameters—particularly interfacial modulus and thickness—influence the mechanical and piezo‑electric behaviour of such systems is still not fully understood. In this work we independently tuned these two parameters in shape‑memory polyurethane/lead zirconate titanate (SMPU/PZT) multifunctional nanofibres to clarify their respective contributions. The results show that interfacial modulus is the dominant factor: as it increases, the fibres’ elastic modulus, tensile strength and open‑circuit voltage rise by up to 297 %, 217 % and 356 %, respectively, demonstrating a strong positive correlation. A stiffer interface also allows the fibres to conform closely to the contours of a human hand and to convert subtle movements into pronounced voltage signals, thereby enhancing both sensing and energy‑harvesting performance. These findings indicate that, to optimise a given function, one must selectively adjust the interfacial parameter that directly governs that function rather than merely strengthening the interface as a whole.