Enhanced energy transfer and conversion for high performance phononic crystal-assisted elastic wave energy harvesting

A critical challenge in energy harvesting has been insufficient sustainable power generation for practical applications, despite the benefits of self-powering and green-enabling technology. Metamaterials are artificial structures capable of controlling and manipulating functionalities beyond the limit of natural materials. Various metamaterial concepts including phononic crystals (PnCs) and locally resonant metamaterials have proved to manipulate mechanical waves and enable amplification of input mechanical wave energy, such as sound, vibration, and ultrasonic waves, thus enabling drastic enhancement of energy harvesting thus far. Along with the need for research on novel metamaterial designs for energy localization and focusing, fundamental understanding of the energy transfer and conversion at the interface between the piezoelectric energy harvesting (PEH) devices and the metamaterial host structure is also crucial to further enhancing the output power performance of metamaterial-based energy harvesting. Here, we report a substantially enhanced harvesting power amplification and output power in phononic crystal-assisted elastic wave energy harvesting by tailoring geometric and materials parameters of a PEH device for a given PnC structure. We envision that the underlying wave physics and materials science in this rational parametric design strategy will contribute to realizing self-powered sensor applications in industrial and environmental monitoring fields.