Polyethyleneimine (PEI)-Treated Multifunctional Textile Triboelectric Nanogenerator: A Scalable and Cost-Effective Solution for Self-Powered Electronics, Energy Harvesting and Physiological Movement Monitoring

Cotton, due to its abundance, low cost, and extensive use in textile manufacturing, is a promising material for textile triboelectric nanogenerators (T-TENGs); however, its position in the neutral region of the triboelectric series results in lower triboelectric performance. This study addressed this limitation by treating cotton with polyethyleneimine (PEI) via scalable pad-dry method. The PEI treatment enhanced tribo-positivity and provided its additional benefits, like antibacterial (83.33%) and antioxidant (74.2%) properties. In this work, we explored PEI-treated cotton fabric for T-TENG devices aimed at energy harvesting, self-powered electronics, and physiological movement monitoring. The 10% PEI-treated cotton T-TENG demonstrated a significant increase in electrical performance, with increments in output voltage and current by 3.4-fold (from ~30 V to ~103 V) and 3.27-fold (from ~3.36 µA to ~11 µA), respectively, under a contact pressure of 16 N (25.6 kPa) and a frequency of 8 Hz. Additionally, the device achieved a maximum power density of ~1600 mW/m² at 10 MΩ resistance. The device's practical applications were demonstrated through its ability to charge capacitors of various capacitance values, power a series of more than 70 LEDs and operate off-the-shelf electronics like wristwatch, digital timer, and humidity sensor. Additionally, the T-TENG functioned as a pressure sensor, in monitoring joint movements when attached to body joints (e.g., wrist, elbow, shoulder, knee), offering applications in athlete motion tracking. This study provided a new pathway for developing flexible, cost-effective, and biocompatible T-TENGs, advancing their potential for energy harvesting and self-powered sensing in wearable technologies.