Low-frequency vibration energy harvesting: a comprehensive review of frequency up-conversion approaches

Abstract

Abstract Along with the rapid development of low-power electronics and the Internet of Things, vibration energy harvesting is attracting increasingly attention from both industry and academia. However, most reported energy harvesters are inefficient in real applications where excitation sources mostly are unpredictable and low frequency. To harness low-frequency vibration energy, the concept of frequency up-conversion is proposed and a variety of designs and analysis has been reported. This article presents a critical review on frequency up-conversion vibration energy harvesters (FUCHs) based on two classification principles: (a) interaction mechanisms as contact and noncontact types; and (b) excitations as type of inertial vibration and type of direct loading. Furthermore, we illustrate the applications of FUCHs designed for harvesting energy from the low-frequency human motions and propose the feasible future research directions of FUCHs.