Efficient energy harvesting from broadband low-frequency vibrations via 3D-interdigital electrostatic generator

Abstract

Vibration energy harvesting offers a promising alternative to address the battery life limitations of sensor nodes. To efficiently harvest broadband low-frequency vibration energy, a 3-dimensional interdigital multi-layered vibration energy harvester (3D-MVEH) is proposed, where the full-scale output can be achieved with small displacement under vibration at micro amplitude. The design with small air gaps enhances the output power by realizing high charge density without air-breakdown and feasible to achieve full output, resulting in a theoretical 1.55 times higher electric energy density than the single-layered harvester with the same volume. The 3D-MVEH achieved a normalized power density (NPD) of 79.4 μWcm⁻³ g⁻² with 60 Hz bandwidth (20–80 Hz). Based on the broadband response and high power density, both transient impulse (e.g. shock) and random vibration can be effectively harvested. Especially, an autonomous wireless alarmer was constructed, which was triggered and powered by a coin dropping from over 20 cm. This work opens up new possibilities for vibration energy harvesting and self-powered wireless sensing, particularly for maintenance-free autonomous emergency alarms.