Fabrication and performance of silicon-embedded permanent-magnet microgenerators

Florian Herrault, Bernard C. Yen, Chang Hyeon Ji, Zoltan S. Spakovszky, Jeffrey H. Lang, Mark G. Allen

Research output: Contribution to journalArticlepeer-review

20 Scopus citations


This paper focuses on the design, fabrication, and characterization of silicon-packaged permanent-magnet (PM) microgenerators. The use of silicon packaging favors fine control on shape and dimensions in batch fabrication and provides a path toward high rotational speeds (∼ 1 Mr/min), a requirement for ultimate compactness of microgenerators. The successful silicon packaging of these microgenerators consisted of three essential elements: 1) a winding scheme allowing both nonplanar fabrication and through-wafer interconnects; 2) laminations built into the silicon for enhanced electrical performance; and 3) a balancing scheme for the heavy PM rotor to ensure its maximum performance. The devices were fabricated using bonded silicon wafers, integrated magnetics, and an electroplated metal. The mechanical strength of the 12-mm-diameter silicon-packaged PM rotors was evaluated at high rotational speeds using an external spindle drive. Speeds up to 200000 r/min were achieved prior to a mechanical rotor failure. The generators were electrically characterized, and an output power in excess of 1 W across a resistive load of 0.32 Ω was measured at a maximum speed. A 225% power increase was also experimentally determined due to the addition of a laminated stator back iron.

Original languageEnglish
Article number5350699
Pages (from-to)4-13
Number of pages10
JournalJournal of Microelectromechanical Systems
Issue number1
StatePublished - Feb 2010

Bibliographical note

Funding Information:
Manuscript received June 11, 2009; revised October 13, 2009. First published December 8, 2009; current version published February 3, 2010. This work was supported in part by the Army Research Laboratory (DAAD19-01-2-0010) under the Collaborative Technology Alliance in Power and Energy program. Subject Editor R. R. A. Syms.


  • AC generators
  • Interconnects
  • Laminations
  • Microgenerator
  • Permanent magnets (PMs)
  • Silicon packaging


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