“…Therefore, the question of how to harvest energy from the surrounding environment to power these devices, instead of simply using batteries, has attracted widespread attention [ 3 , 4 , 5 , 6 ]. There are many forms of energy in the natural environment, such as solar energy, wind energy, vibration energy and thermal energy [ 7 , 8 , 9 , 10 ], and the commonly used energy harvesting mechanisms include photoelectric, piezoelectric [ 11 , 12 ], electromagnetic [ 13 , 14 , 15 ], electrostatic [ 16 ] and triboelectric effects [ 17 , 18 ]. In particular, there are abundant vibration energy sources in the natural environment, most of which are low-frequency vibration [ 19 ].…”