Flexible and multi-directional piezoelectric energy harvester for self-powered human motion sensor

Min Ook Kim, Soonjae Pyo, Yongkeun Oh, Yunsung Kang, Kyung Ho Cho, Jungwook Choi, Jongbaeg Kim

Research output: Contribution to journalArticlepeer-review

46 Citations (Scopus)


A flexible piezoelectric strain energy harvester that is responsive to multi-directional input forces produced by various human motions is proposed. The structure of the harvester, which includes a polydimethylsiloxane (PDMS) bump, facilitates the effective conversion of strain energy, produced by input forces applied in random directions, into electrical energy. The structural design of the PDMS bump and frame as well as the slits in the piezoelectric polyvinylidene fluoride (PVDF) film provide mechanical flexibility and enhance the strain induced in the PVDF film under input forces applied at various angles. The amount and direction of the strain induced in PVDF can be changed by the direction of the applied force; thus, the generated output power can be varied. The measured maximum output peak voltage is 1.75, 1.29, and 0.98 V when an input force of 4 N (2 Hz) is applied at angles of 0°, 45°, and 90°, and the corresponding maximum output power is 0.064, 0.026, and 0.02 μW, respectively. Moreover, the harvester stably generates output voltage over 1.4 104 cycles. Thus, the proposed harvester successfully identifies and converts strain energy produced by multi-directional input forces by various human motions into electrical energy. We demonstrate the potential utility of the proposed flexible energy harvester as a self-powered human motion sensor for wireless healthcare systems.

Original languageEnglish
Article number035001
JournalSmart Materials and Structures
Issue number3
Publication statusPublished - 2018 Jan 29

Bibliographical note

Funding Information:
This work was supported by the Basic Research Foundation of Defense Acquisition Program Administration and Agency for Defense Development

Publisher Copyright:
© 2018 IOP Publishing Ltd.

All Science Journal Classification (ASJC) codes

  • Signal Processing
  • Civil and Structural Engineering
  • Atomic and Molecular Physics, and Optics
  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanics of Materials
  • Electrical and Electronic Engineering


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