A Flexible and Stretchable Triboelectric Nanogenerator with Agarose/P(HEA-co-AA)-Al/NaCl Electrodes for Bio-Mechanical Energy Harvesting and Fall Detection.

Recent advancements in wearable electronics for fall detection have shown significant potential, yet challenges remain in developing reliable, energy-efficient systems capable of continuous monitoring in real-world conditions. In this work, a double-network (DN) conductive hydrogel, comprising NaCl-coordinated agarose and poly (2-hydroxyethyl acrylate-co-acrylic acid) (Agarose/P(HEA-co-AA)-Al/NaCl) (APA-hydrogel), was synthesized. The agarose forms a stable first network, while the second network is established by P(HEA-co-AA) through aluminum ion coordination. Immersion in NaCl solution leads to the formation of hydrated sodium ions ([Na(H₂O)n]⁺), which are anchored within the hydrogel matrix via hydrogen bonding and metal coordination. The resulting APA-hydrogel was applied as a triboelectric nanogenerator (APA-TENG), demonstrating excellent performance with an open-circuit voltage of 900 V, a short-circuit current of 73.42 μA, and a peak power output of 3.52 mW at a 3 MΩ load. APA-TENG shows strong potential for energy harvesting and powering low-power devices, as well as real-time sensing for motion and fall detection, making it highly suitable for wearable and assistive technologies powered by human activity.