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Proceedings Paper

MEMS capacitors with dual cavity for power harvesting
Author(s): N. S. Yuksek; J. Zhu; Z. C. Feng; M. Almasri
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Paper Abstract

The modeling, fabrication and testing of a two-cavity MEMS capacitor utilizing inertial forces from unwanted ambient vibrations has been performed. The device was designed with two air cavities and a thick movable metallic plate in order to increase the efficiency of the energy conversion from mechanical vibration. The moving plate was sandwiched between two fixed plates to construct a two cavity capacitor. The improved model verified the fact that that two-cavity model enhances the average output power by 2 to 5 times of a single cavity model. The device was designed with soft suspension beams and with a thick plate in order to achieve a natural frequency close to the ambient vibration frequencies. The FEM analysis showed that a thick electroplated nickel plate and beams can results in a natural frequency less than 1 kHz. The behavior of the plate under damping was also calculated using FEM analysis. The MEMS converters were fabricated using surface micromachining technology, nickel electroplating and photoresist sacrificial layer. The moving plate and suspension beams were grown on the photoresist sacrificial layer and nickel anchors. The structure was released by removing the photoresist sacrificial layers using photoresist strip remover. To form the top cavity, nickel bonding tabs with sufficient thickness were grown by electroplating on another substrate followed by indium electroplating with a thickness of 1 μm. The two substrates were then aligned and bonded together. A good control of the height of the two cavity MEMS capacitor is possible with the control of Ni deposition and sacrificial layer thicknesses.

Paper Details

Date Published: 24 May 2012
PDF: 8 pages
Proc. SPIE 8377, Energy Harvesting and Storage: Materials, Devices, and Applications III, 83770P (24 May 2012); doi: 10.1117/12.919543
Show Author Affiliations
N. S. Yuksek, Univ. of Missouri-Columbia (United States)
J. Zhu, Univ. of Missouri-Columbia (United States)
Z. C. Feng, Univ. of Missouri-Columbia (United States)
M. Almasri, Univ. of Missouri-Columbia (United States)

Published in SPIE Proceedings Vol. 8377:
Energy Harvesting and Storage: Materials, Devices, and Applications III
Nibir K. Dhar; Priyalal S. Wijewarnasuriya; Achyut K. Dutta, Editor(s)

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