High performance nonlinear micro energy harvester integrated with (K, Na)NbO3/Si composite quad-cantilever

We developed a lead-free (K, Na)NbO
3
nonlinear micro energy harvester. The harvester was densely integrated with a quatrefoil-shaped proof mass and quad-cantilevers using bulk micromachining. The KNN/Si composite cantilever was integrated with two-separated metal (Pt/Ti)/ KNN/ metal (Pt/Ti) structure to effectively collect charge. Clamped-clamped beam design was also adopted for wide band operation. The harvester showed wide bandwidth of 253 Hz (fractional bandwidth: 12.9%) at acceleration of 6 m/s
²
. The power density of 1623 μW/cm
³
was achieved at the same acceleration. It is the highest value among the wide bandwidth piezoelectric energy harvesters.