Polyurethane-Based Electrostrictive Nanocomposites as High Strain–Low Frequency Mechanical Energy Harvesters

Harvesting of wasted mechanical energy is increasingly important for powering wearable electronics in the Internet-of-Things world. Here, we report on innovative nanocomposites made of thermoplastic polyurethane and a high-dielectric constant ceramic nanofiller (CaCu3Ti4O12), which offer good results in recovering energy by human gait. Power densities of the order of 300 μW cm–3 at 12% strain were obtained with 50 vol % of the filler. The film was strained more than 105 times without losing its properties. By means of careful broadband electric spectroscopy coupled with microstructure analysis, we were able to address the mechanisms underlying energy recovery. Our model allows optimal tailoring of electrostrictive nanocomposite harvesters.