A sandwich-structured MEMS electret power generator for multi-directional vibration energy harvesting

This paper presents the design, modeling and characterization of a compact MEMS electret power generator for multi-directional vibration energy harvesting. The device is built on a symmetrical square-shape resonator that could harvest kinetic energy from multiple directions by using two orthogonal vibration degrees of freedom. Sandwich structure is adopted not only to enhance the output performance, but also to reduce both vertical pull-in and horizontal electrostatic damping force with two separate 180° out-of-phase capacitive circuit. The generator can be a potential candidate towards a practical multi-directional energy harvesting device for low-level ambient vibrational energy harvesting.