Electromagnetic linear vibration energy harvester using sliding permanent magnet array and ferrofluid as a lubricant

Song Hee Chae, Suna Ju, Yunhee Choi, Ye Eun Chi, Chang Hyeon Ji

Research output: Contribution to journalArticlepeer-review

32 Scopus citations


We present an electromagnetic linear vibration energy harvester with an array of rectangular permanent magnets as a springless proof mass. Instead of supporting the magnet assembly with spring element, ferrofluid has been used as a lubricating material. When external vibration is applied laterally to the harvester, magnet assembly slides back and forth on the channel with reduced friction and wear due to ferrofluid, which significantly improves the long-term reliability of the device. Electric power is generated across an array of copper windings formed at the bottom of the aluminum housing. A proof-of-concept harvester has been fabricated and tested with a vibration exciter at various input frequencies and accelerations. For the device where 5 μL of ferrofluid was used for lubrication, maximum output power of 493 μWhas been generated, which was 4.37% higher than that without ferrofluid. Long-term reliability improvement due to ferrofluid lubrication has also been verified. For the device with ferrofluid, 1.02% decrease of output power has been observed, in contrast to 59.73% decrease of output power without ferrofluid after 93,600 cycles.

Original languageEnglish
Article number288
Issue number10
StatePublished - 22 Sep 2017

Bibliographical note

Publisher Copyright:
© 2017 by the authors.


  • Electromagnetic generator
  • Energy harvester
  • Ferrofluid
  • Low frequency vibration


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