Spatial engineering of textile threads for all-textile embroidered triboelectric nanogenerators

Abstract

Triboelectric nanogenerators (TENGs) are envisioned to become a leader in wearable energy-harvesting and self-powered sensing applications with textile-based TENGs playing a major role due to their comfort. However, textile TENGs face challenges including lower electrical outputs, low charge stability, and sporadic outputs, mainly due to lack of fibre/yarn-level TENG optimization strategies. These devices are predominantly constructed using fabric-level triboelectric modifications, at which stage, scope for their optimization is limited. Therefore, significant attention is needed to design and optimize fibre/yarn-level TENGs that can function as wearable sensors with excellent electrical, wearable, and mechanical performance. Herein, we introduce spatial engineering and optimisation techniques at fibre/yarn level of a textile using an embroidery technique to construct high-performance wearable TENG devices. For the first time, this work provides a comprehensive theoretical and experimental study on how fundamental embroidery parameters—such as stitch spacing, stitch length, and stitch direction—can be systematically varied to optimize TENG outputs, demonstrating significant increase in their performance. These TENGs were then used as self-powered active sensors for monitoring elbow movement on human subjects. Compared to gold-standard optoelectronic sensors and commercial inertial measurement units, these sensors provided excellent accuracy and repeatability, highlighting a landmark study in this research field.