Metasurfaces for Enhanced Energy Harvesting in MEMS with Lead-Free Piezoelectric Material

Inspired by recent graded metamaterials designs, we create an innovative MEMS that combines a graded metamaterial with lead-free piezoelectric material for enhanced energy harvesting. The metamaterial is made of a graded array of resonators to achieve the so-called rainbow effect for the propagation of elastic waves along a suspended waveguide. Numerical models and experiments demonstrate that the rainbow effect increases the wavefield amplitude, inducing a boosted interaction with the resonators. The latter are equipped with lead-free piezoelectric material, namely Aluminium Nitride (AlN), and the device can transduce elastic energy into electric energy with a significant enhancement with respect to a single resonator without the metamaterial.