Sponge-like piezoelectric micro- and nanofiber structures for mechanical energy harvesting

Herein, the one-step fabrication of novel three-dimensional sponge-like piezoelectric electrospun nanofiber structures is reported. Ferroelectric polymers are biocompatible and flexible materials that present attractive opportunities for the fabrication of portable energy harvesters for energy efficient wearable electronic devices. While being compatible with diverse fabrication methods, thicker and denser 3D forms have only been obtained from extruder-based, low-yield approaches. Electrospinning polyvinylidene fluoride (PVDF) and polyvinylidene fluoride-co-trifluoroethylene (PVDF-TrFE) solutions with added polyethylene oxide (PEO) and lithium chloride was explored as an alternative approach for the scaled-up fabrication of 3D structures. The resulting PVDF/PEO and PVDF-TrFE/PEO 700 mu m thick sponge-like fiber mats were used as active cores for piezoelectric generators. The produced sponge-like core generators achieved an average peak-to-peak voltage of 69.4 V when subjected to a 1.58 N impact force applied at a frequency of 4 Hz and connected to a 15.1 M omega resistive load. Their measured instantaneous output power of 40.7 mu W cm-2 exceeds that of similar state-of-the-art generators by a factor of 2. Our fabrication method provides a low-cost, one-step, and scalable alternative for creating micro-and nano fibrous three-dimensional structures.

Automated summary

This paper reports a one-step method for fabricating novel three-dimensional sponge-like piezoelectric electrospun nanofiber structures. By adding polyethylene oxide and lithium chloride to polyvinylidene fluoride and polyvinylidene fluoride-co-trifluoroethylene solutions, 700 micrometer thick sponge-like fiber mats were created and used as active cores for piezoelectric generators. The resulting generators showed higher peak-to-peak voltage and instantaneous output power.