A fully enclosed, 3D printed, hybridized nanogenerator with flexible flux concentrator for harvesting diverse human biomechanical energy

This work presents a fully-enclosed wrist-wearable hybridized electromagnetic-triboelectric nanogenerator (FEHN) for scavenging energy from low-frequency human wrist-motion (≤ 5 Hz). The FEHN utilizes a freely moving magnetic ball inside a circular tube to combine rolling electrostatic induction and electromagnetic induction. A flexible flux concentrator is used to enhance the electromagnetic output.

• Development of a fully-enclosed, wrist-wearable hybridized nanogenerator (FEHN).
• Effective energy harvesting from diverse and irregular low-frequency wrist motions.
• Introduction of a flexible flux concentrator to enhance electromagnetic performance.
• Fabrication using easy, quick, and cost-effective 3D-printing technology.

The device was fabricated using 3D printing. It consists of a hollow circular tube containing a freely moving magnetic ball. The system performance was evaluated by its ability to harvest energy from various wrist motions like swinging, waving, and shaking, and its capacity to power commercial electronics.

The FEHN achieves an average power density of 0.118 mW cm⁻³ and can power a commercial wristwatch continuously for more than 23 minutes from just 5 seconds of wrist motion. This demonstrates an effective approach for a sustainable power supply for wearable devices.