2D Woven Core‑Shell Fiber Triboelectric Nanogenerator Harvests Body Motion into 6 V, 575 nA, Powering LEDs and Capacitors

Abstract

Wearable electronics demand compact, autonomous power sources that can tap ambient kinetic energy. Here we present a two‑dimensional woven triboelectric nanogenerator (2DW‑WTNG) built from core‑shell fibers that convert human motion into electricity. The device delivers 6.35 V peak voltage and 575 nA peak current, corresponding to a power density of 2.33 mW m⁻² at a 50 MΩ load. Remarkably, it generates charge from displacements as small as 0.4 mm and operates continuously for 12 h without performance loss.

Introduction

Portable, wearable, and implantable devices have proliferated, yet conventional batteries fall short in capacity, lifespan, and environmental impact. Harnessing the mechanical energy inherent in daily human activity offers a sustainable alternative. Triboelectric nanogenerators (TENGs) convert contact‑induced charge separation and electrostatic induction into usable electricity. While numerous TENG designs exist, many rely on fragile substrates that compromise durability. Our 2DW‑WTNG eliminates this limitation by integrating core‑shell conductive fibers directly into a woven fabric, enabling robust, scalable production.

Methods

Fabrication of Core‑Shell Composite Fibers

We combined sewing nylon threads (110 µm) with enameled copper wires (60 µm) and sewing polyester threads (200 µm) with steel wires (60 µm) using a rotating support that mimics hand‑twisting. This process yields 380 µm‑diameter nylon/copper and 385 µm‑diameter polyester/steel fibers, each featuring a metal core surrounded by a polymer sheath. The copper core is insulated to prevent short‑circuiting, while the steel core provides structural strength.

Weaving the 2DW‑WTNG

Four groups of nylon/copper fibers and four groups of polyester/steel fibers were knitted orthogonally to form a 15 mm × 15 mm active area with 7 mm grating width. The resulting fabric resembles conventional textile, making it compatible with industrial looms for mass production.

Electrical Characterization

The device was actuated by a linear motor, driving the upper layer against the lower layer in a reciprocating sliding motion. Output current and voltage were recorded under varying sliding speeds, displacements, and relative orientations.

Results and Discussion

The sliding contact between nylon (triboelectrically positive) and polyester (triboelectrically negative) generates alternating charge transfer, driving electrons between the two electrode layers. Peak outputs of 575 nA and 6.3 V were achieved at 8 mm displacement and 0.15 m s⁻¹ speed. Power density peaked at 2.33 mW m⁻² when connected to a 50 MΩ resistor.

Increasing sliding speed enhanced peak values: at 0.125 m s⁻¹, the current rose to 415 nA and voltage to 6.6 V. Smaller displacements down to 0.4 mm still produced measurable outputs (2.3 nA, 0.05 V), demonstrating sensitivity to minimal human motion.

The device maintained performance across various in‑plane orientations, delivering 134 nA and 2.23 V at a 50° relative angle, confirming its adaptability to arbitrary body movements.

When connected to a bridge rectifier, the 2DW‑WTNG immediately powered a red LED and charged a 0.47 µF capacitor to 1.84 V within 1 min, storing 3.84 mC m⁻². Continuous operation for 12 h showed negligible degradation, underscoring its mechanical resilience.

Conclusions

The 2DW‑WTNG demonstrates a scalable, durable platform for harvesting human motion energy. Its core‑shell fiber architecture and woven design deliver high voltage, sufficient current for low‑power electronics, and robust operation under varied motion directions. This technology paves the way for truly autonomous wearable devices.