Table 5.

Comparison of methods for broadband being pursued in the area of energy harvesting.

Type	Advantages	Disadvantages
Resonance-based tuning	More efficient to harvest more net energy at various frequencies Changing system effective stiffness is an effective way to tune frequencies. The effective stiffness tuning approach can be adapted for MEMS device. Preferable in piezoelectric and magnetic EH mechanisms.	Changing the effective mass or adjusting the geometries of EH are difficult to be performed in practice. The induced additional stiffness may require extra system and energy to realize tuning approaches. Damping maybe increased in some cases (such as in axial stiffness tuning) Limited frequency tuning range
Expanding bandwidth	Completely passive approach, no energy required for tuning Nonlinear EH improves the performance with a wider bandwidth Fast response of bistable EH	Limitation of design space for multiple discrete elements Power density decreases Complex energy storage design When one structure is in resonance, while the other (n − 1) structure will not be in resonance, limiting the device performance Complexity in design and implementation regarding the interdependence parameters for practical implementation