Vibration energy harvester with double frequency-up conversion mechanism for self-powered sensing system in smart city

Abstract

This paper has proposed a vibration energy harvester (VEH) with double frequency-up conversion (FUC) mechanism which can be applied to harvest energy from vibrations at ultra-low frequency. The device can initially up-convert the external vibrations with sub-Hertz into tens of Hertz, and further convert to hundreds of Hertz by the second FUC mechanism, which gives a high conversion ratio of 8400. A comprehensive dynamic model has been proposed and verified both from the theoretical analysis and COMSOL simulation to analyze the frequency conversion process and output voltage. When excited by a frequency of 0.2 Hz, an average output power of 75 μW could be obtained with a compact size. Benefiting from the non-contact design, the device could be applied in some sealed scenarios for smart city construction. Herein, a wireless humid-temperature sensor node in the pipeline was successfully powered by harvesting energy from humans walking with the proposed VEH, showing promising application prospects.