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

• Published in: Journal of micromechanics and microengineering Vol. 16; no. 2; pp. 235 - 241
• Main Authors: Gracewski, S M, Funkenbusch, P D, Jia, Z, Ross, D S, Potter, M D
• Format: Journal Article
• Language: English
• Published: Bristol IOP Publishing 01.02.2006; Institute of Physics
• Subjects: Applied sciences; Electronics; Exact sciences and technology; Instruments, apparatus, components and techniques common to several branches of physics and astronomy; Mechanical engineering. Machine design; Mechanical instruments, equipment and techniques; Microelectronic fabrication (materials and surfaces technology); Micromechanical devices and systems; Physics; Precision engineering, watch making; Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices; Encapsulation; Natural frequency; Electric generator; Microelectronic fabrication; Proximity; Output power; Battery; Measurement sensor; Lumped parameter system; Energy recovery; Secondary cell; Modeling
• ISSN: 0960-1317; 1361-6439
• DOI: 10.1088/0960-1317/16/2/007

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 muW 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.