A potassium electret energy harvester for 3D-stack assembly

We report an electrostatic energy harvester based on the potassium ion (K
⁺
) electret that could be stacked up into a 3D structure to multiply the output power. Vertical comb electrodes are implemented in a silicon-on-insulator (SOI) wafer with a relatively heavy mass in the handle layer to lower the resonance. A single substrate formation exhibited a 0.34 µW output at 310 Hz for a load resistance of 1 MΩ.