Supersonically sprayed PVDF and ZnO flowers with built-in nanocuboids for wearable piezoelectric nanogenerators

Bhavana Joshi, Jaewoo Seol, Edmund Samuel, Woojin Lim, Chanwoo Park, Ali Aldalbahi, Mohamed El-Newehy, Sam S. Yoon

Research output: Contribution to journalArticlepeer-review

23 Citations (Scopus)


Healthcare implant devices that can internally generate a flow of electrical charge driven by mechanical stimuli are in demand. Such self-powered electromechanical devices are known as piezoelectric nanogenerators (PENGs). In this study, a piezo-ceramic element of hydrothermally synthesized ZnO flowers comprising built-in nanocuboids was supersonically sprayed with piezo-polymer polyvinylidene fluoride (PVDF) to fabricate ZnO-embedded PVDF films for flexible PENG devices. In the presence of ZnO, the catastrophic supersonic impact and shear flow transformed the nonpolar α-phase of PVDF into the polar β-phase. The combination of ZnO flowers with built-in nanocuboids and β-phase-rich PVDF can help enhance generated charges at interfacial sites under an applied force. The supersonically sprayed PVDF/ZnO composite exhibited a 32% increase in the β-phase compared to that exhibited by pure PVDF prior to supersonic coating. The effective piezoelectric coefficient values (d33*) of the pure PVDF and PVDF/ZnO composite films were 43 and 150 pm·V‐1, respectively; the corresponding open-circuit voltages were 1.2 and 25.5 V, respectively. These significant differences confirm the pivotal role of ZnO in increasing the β-phase within PVDF during supersonic spraying. The form of the externally applied force and frequency were varied to evaluate the electromechanical performance of PVDF/ZnO. The energy harvesting capability of the composite was demonstrated using 33 light-emitting diodes.

Original languageEnglish
Article number108447
JournalNano Energy
Publication statusPublished - 2023 Jul

Bibliographical note

Funding Information:
This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government NRF-2020R1A5A1018153 , NRF-2021R1A2C2010530 , and 2022M3J1A106422611 . The authors acknowledge King Saud University, Riyadh, Saudi Arabia, for funding this work through Researchers Supporting Project number ( RSP2023R30 ).

Publisher Copyright:
© 2023 Elsevier Ltd


  • Energy harvesting
  • Piezoelectric nanogenerator
  • Supersonic spraying
  • Wearable device

ASJC Scopus subject areas

  • Renewable Energy, Sustainability and the Environment
  • General Materials Science
  • Electrical and Electronic Engineering


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