A variable-capacitance energy harvester with miniaturized inductor targeting implantable devices

Seyed Hossein Daneshvar, Mohammad Maymandi-Nejad, Mehmet Rasit Yuce, Jean Michel Redoute

Research output: Contribution to journalArticleResearchpeer-review

3 Citations (Scopus)


Many variable-capacitance energy harvesters employ a large inductor to improve their power efficiency by reducing conduction losses, which is sub-optimal in applications requiring a small form-factor, such as in implants. This paper describes a variable-capacitance harvester that performs optimally using miniaturized inductors. The impact of scaling the inductor on the generated energy of conventional semi-synchronous and fully-synchronous charge-constraint topologies is investigated analytically as well as experimentally. It is shown that the proposed harvester outperforms the semi-synchronous and fully-synchronous charge-constraint harvesters while using very small inductance values. Using two reservoir capacitors to generate energy without requiring large inductors, as well as utilizing a different switching scheme are the main factors contributing to this advantage. Since harvesting energy from slow moving mechanical sources, such as body movements, constitutes a major challenge, all three harvesters are implemented and tested with an actuating frequency as low as 0.5 Hz and for inductance values between 1 uH to 1 mH. The experimental results for sample designs corroborate the analytical expressions and show that to generate optimal harvested energy of the proposed harvester, the semi-synchronous harvester requires a 15.6 times larger inductor.

Original languageEnglish
Pages (from-to)475-484
Number of pages10
JournalIEEE Transactions on Industrial Electronics
Issue number1
Publication statusPublished - Jan 2022


  • Capacitance
  • Capacitors
  • electrostatic generators
  • Energy harvesting
  • implantable devices
  • Implants
  • Inductors
  • Investment
  • micro-generators
  • Reservoirs
  • Switches
  • variable capacitors

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