Design and modeling of a micro-energy harvester using an embedded charge layer

The harvesting of energy from the environment represents a potentially attractive power source for some microdevices, especially in applications where external power connections or batteries are cumbersome or impractical. This paper describes a novel energy harvester based on the motion of a metallic beam/electrode in proximity to a fixed layer of embedded monopole electrical charge. The proposed device can be fabricated with traditional IC fabrication techniques and therefore could allow smaller packaged sensor designs. A lumped-parameter model is developed to explore the design space available for this device and is used to estimate the power densities that can be obtained with different design configurations. The output is strongly dependent on the assumed ambient conditions, but power densities of interest for lower power applications in the order of 1 µW cm −2 appear to be achievable. Beam stability against 'snap-down' is shown to be a key design constraint, limiting device geometry and, thus, natural frequency and power output.