Optimizing the Substrate-to-Piezoelectric Thickness Ratio of Micro-Fabricated Aln-on-Si Vibration Energy Harvesting

Cantilever is a popular design choice for MEMS vibration energy harvesting due to its high responsiveness to ambient kinetic agitations. Design optimizations have been extensively covered in the literature within the two-dimensional topological space. As with any MEMS process, topological optimization is often easier and more cost effective to carry out than thickness or material stack optimization, as the fabrication process does not need to be altered for the former. This paper outlines a thickness ratio optimization between the substrate and piezoelectric layers. Over an order of magnitude improvement in power density was experimentally observed, and a peak power of
$384\ \mu \mathrm{W}$
within a 1 cm
²
die area was attained for 0.6 g and 558 Hz of excitation within 5 mbar vacuum condition.