Bioinspired Flexible and Stretchable Coil Structure from Ti₃C₂T_x MXene/AgNPs-Functionalized Piezoelectric Nanofibers for Enhanced Energy Harvesting

Abstract

The growing popularity of smart electronics in wearables, the Internet of Things (IoT), soft robotics, and biomedical implants simultaneously demands more reliable and durable power sources. However, limitations on battery life continue to compromise reliability, prompting the search for sustainable solutions for flexible, self-powered systems. In this work, stretchable self-powered piezoelectric nanogenerators have been designed from functionalized piezoelectric nanofibers with a bioinspired coiled helical microstructure. Composed of two-dimensional (2D) Ti₃C₂T_x MXene and silver nanoparticles (AgNPs) embedded in a poly(vinylidene fluoride-co-trifluoroethylene) (P(VDF-TrFE)) matrix, the coiled structure achieves a mechanoelectrical energy conversion efficiency of 17%, and a power output of 6.6 mW cm⁻³ at 50% strain, twice the performance of similarly coiled structures. These improvements were attributed to the threefold increase in the piezoelectric coefficient through the addition of 1 wt% AgNPs to the P(VDF-TrFE)/MXene (0.1 wt%) and the coiled structure further enhancing β-phase formation reaching up to 70%. An electrospun mat sensor with dimensions of 2 × 3 cm generated 3 V at 1 Hz under an applied pressure of 7 kPa. The coil compact and lightweight design enables seamless integration into miniaturized electronics and wearable biomedical devices, promising a sustainable, battery-free power solution.