A Novel Non-Resonant Energy Harvester for Ultra-Low-Frequency Energy Harvesting from Human Walking

Harvesting energy from human walking offers a promising alternative to batteries for powering wearable devices. However, existing energy harvesters suffer from limited power output. So, a novel non-resonant energy harvester was proposed in this paper. The core mechanism of the harvester integrates three components: a helical twin-rod twist rod, a face gear with dumbbell-shaped holes, and a rotor featuring bevel teeth on its upper surface. This core mechanism can efficiently harvest low-frequency reciprocating motion and convert it into unidirectional rotational motion, thereby enabling highly efficient acquisition of low-frequency energy. It offers advantages such as high energy harvesting efficiency and a simple structure. Then an electromagnetic generator converts this rotational energy into electricity. A prototype of the proposed harvester was developed and tested on a vertical reciprocating motion platform. Experiments investigated the influence of parameters including human input energy and mechanical harvesting structure on output performance of the harvester. Application testing demonstrated that manual pressing at 1 Hz successfully illuminated 120 LEDs. When integrated into a shoe heel and tested with a 60 kg person stepping in place at 2 steps per second, the harvester achieved an RMS output voltage of 18.5 V, an output power of 263.27 mW, and a power density of 4.21 mW/cm3. Overall, this research presents a new approach for designing high-efficiency energy harvesters for human walking applications.