Strain-induced electrification-based flexible nanogenerator for efficient harvesting from ultralow-frequency vibration energy at 0.5-0.01 Hz

The demand for self-powered devices, particularly in biomedical and wearable technology, emphasizes efficient powering from ultralow-frequency vibrations. While triboelectric nanogenerators have shown potential, they still face challenges in powering below 0.1 Hz and suffer from tribological issues. Herein, we introduce a novel nanogenerator capitalizing the strain-dependent characteristics of the work function of gold. Our device achieves efficient power generation at 0.01 Hz, with a current density of 2.3 mA m⁻², marking a significant breakthrough. At 0.5 Hz, it reaches 4.8 mA m⁻², demonstrating substantial improvement over prior performance. Moreover, by eliminating repetitive contact-separation processes found in triboelectric nanogenerators, our generator exhibits no performance degradation due to tribological damage after 1 000 000 cycles. Integrated into a watch strap, it powers LEDs and generates Morse code signals via finger grasping, offering an innovative method for distress communication when conventional power sources are unavailable. The wide material selectivity for strain-modifiable work functions suggests promising research avenues.