Graded Micro-Resonators For Enhanced Sensing and Energy Harvesting In MEMS With Lead-Free Piezoelectric Materials

Leveraging recent advancements in graded metamaterial designs, this work develops a novel MEMS that integrates a graded metamaterial with a lead-free piezoelectric material to enhance energy harvesting. The metamaterial consists of a graded array of resonators, enabling the so-called rainbow effect for elastic wave propagation along a suspended waveguide. Both numerical simulations and experimental results show that the rainbow effect increases the wavefield amplitude, leading to an intensified interaction with the resonators. These resonators are equipped with lead-free piezoelectric material, specifically Aluminium Nitride (AIN), allowing the device to convert elastic energy into electrical energy with a significant performance boost compared to a single resonator without the metamaterial.