FEM simulation of AlN-based MEMS energy harvester

A device for harvesting the energy of mechanical vibrations and converting it to electricity by the piezoelectric effect is simulated. The main part of the harvester is a multilayer cantilever with a piezoelectric layer sandwiched between two metallic electrodes. The cantilever typically has a rectangular design, which is characterized by insignificant deformation of the free end. As a result, this region undergoes low mechanical stress and produces small amount of electric charge. A tapered shape of the cantilever increases the stress at the tip and, therefore, enhances the performance. In this work, we investigate the stress distribution and output characteristics of the energy harvester with the tapered cantilever. Reducing the width of the free end increases the stress in this area for 4.5 times compared to the conventional design, which raises the average stress by more than 60%. The tapered design increases the output power and voltage by more than 20%.