Piezoelectric Polyurethane/Barium Titanate Composites with High Stretchability and Voltage Output for Energy Harvesting in Soft Wearable Electronics

Abstract The increasing demand for sustainable energy solutions has stimulated interest in technologies that generate electrical energy from ambient mechanical energy. Piezoelectric materials, in this respect, are promising owing to the property of converting mechanical stress into electrical energy and represent an ideal active material platform in applications pertaining to stretchable electronics. However, conventional piezoelectric materials face a dilemma in balancing their mechanical flexibility with efficient energy conversion, limiting their practical applications in wearable devices. This work resolves this challenge by incorporating BaTiO 3 nanoparticles, with high piezoelectric coefficients, into a polyurethane (PU) matrix to develop composite films with balanced stretchability and piezoelectric properties. The PU/BaTiO 3 composite films exhibit a high stretchability of 336% at 30 wt.% BaTiO 3 loading, well above the 55% minimum stretchability required for wearable applications. These films generate a peak‐to‐peak piezoelectric voltage response of ≈31 V under 1 bar compression, proving their capability to efficiently convert mechanical stress into usable electrical energy. The composites are utilized in a piezoelectric energy harvesting system to charge a commercial capacitor, demonstrating practical energy generation from human motion. The findings in this work represents an advancement toward developing flexible energy harvesting devices for wearable electronics and further sustainable energy technologies.