Wideband auto-tunable vibration energy harvester using change in centre of gravity

Energy harvesters are preferred for enhancing the life of IoT nodes. In this paper, a vibration energy harvester with wideband auto-tunable resonant frequency for increased output is designed. With a variation in frequency of vibrating source, harvested energy reduces to zero value. To harvest the energy on regular basis from the vibrating source, tuning is required. This problem is resolved with the proposed design, which works on the principle of change in centre of gravity (CoG) of proof mass that leads to change the natural frequency of the device. The design is simulated and the static change in frequency with a change in CoG is analytically calculated. The simulated results are verified with fabricated device and similar outcome with boosted bandwidth is obtained. Frequency range is obtained between 22–35 Hz for fabricated device with \(\approx\) 6.0 V\(_{pp}\) voltage output for different positions of cylinders.