Effect of carbon black addition on electromechanical performance of flexible piezoelectric composite films

The exponential rate of advancement in flexible electronics and sensing technologies has enabled the detection of diverse vital signs and biomarkers with the use of exceptionally lightweight and flexible devices that affix to human skin. To support the continuous operation of these technologies and to enable them to track their multiple parameters, a flexible, self -powered energy supply unit with a high output is essential. In this work, we develop highly flexible and cost-effective three-phase carbon black (CB)-potassium sodium niobate (KNN)-epoxy resin composite films for sensing and energy -harvesting applications. The mechanical and piezoelectric properties of the films were studied by varying the CB and KNN contents. The potential of the proposed films for sensing and energy -harvesting on complex surfaces was demonstrated using a finger -bending test, during which a tenfold increase in the output voltage was observed for films containing 1 vol% CB. Our study provides a feasible solution for the development of high-performance piezoelectric sensing and energy -harvesting devices in soft wearable electronics.