Harvesting energy from the ambient environment has proved to be an efficient approach for realizing miniaturized devices for sensing. Cognizing the potential of harnessing energy from vibrations led to the emergence of the field of Vibration Energy Harvesting which can help extract the power of the order ranging from microwatts (µW) to milliwatts (mW). Specifically, the piezoelectric method of energy transduction has been widely explored in the literature owing to its high power densities. The narrow operating bandwidth of linear piezoelectric harvesters curtails their use in real-world applications. To overcome the above-mentioned issue, harvesters are designed to operate over a broadband of frequencies.

In this regard, the potential of exploiting the dynamics of coupled nonlinear harvesters in achieving broadband power generation is explored in the present work. Two main harvesting strategies/configurations based on coupled oscillators are investigated for the feasibility of harvesting energy over a broad spectrum namely the multi-modal nonlinear harvester and an array of nonlinear harvesters. Analytical and numerical studies carried out on the former configuration realized through an elastic beam show that in the event of internal resonance between the first two normal modes, the magnitude and bandwidth of harvested power can be enhanced substantially through the activation of modal energy transfer. This considerable increase in the harvesting efficiency from a two-oscillator-based harvester model prompted further studies on the model based on an array of coupled identical nonlinear oscillators. Exploratory analysis of an array of nonlinear harvesters under harmonic excitation showed that the harnessing capacity can be amplified multifold even under low levels of excitation for selective coupling strengths through the emergence of multiple primary and secondary resonances. In the presence of excitation noise, simulation results showed that the total harvested power is found to resonate at certain intensities of noise level and coupling strengths. Amplitude synchronization of harvesters was observed through spatio-temporal plots at the levels of noise at which power is maximized. Limited experiments were conducted to validate the theoretical results presented in this work. The outcomes of this first-hand analysis shall aid in the proposition of an efficient design for a broadband energy harvesting system.