Nanogenerators (NGs) that produce electrical energy from mechanical movement could play an important role in powering portable devices. Typically, such NGs consist of a piezoelectric nanomaterial (e.g., ZnO) that is embedded in a polydimethylsiloxane (PDMS) matrix, forming film-like materials. Such materials are difficult to produce on a large scale and typically harvest energy only when moved along certain directions.

Ki-Seok An, Korea Research Institute of Chemical Technology, Daejon, Republic of Korea, and colleagues have developed a flexible fibre-like NG material that can generate electricity when moved along arbitrary directions. In the first step, a titanium fiber was subjected to anodic oxidation, which formed TiO₂ nanotube (NT) arrays on the fiber’s surface. The TiO₂ was then hydrothermally converted to the perovskite PbTiO₃ without loss of the NT array structure.

Two of the obtained fibers were assembled into a core-shell NG device by embedding them in PDMS. Such devices could generate 69.74 ± 10.97 mV when moved by an air current. According to the researchers, these findings are a step towards the use of NGs for energy harvesting from wind and for applications in portable devices or sensors.

• Toward Arbitrary-Direction Energy Harvesting through Flexible Piezoelectric Nanogenerators Using Perovskite PbTiO₃ Nanotube Arrays,
  Young Bum Lee, Jin Kyu Han, Suttinart Noothongkaew, Seong Ku Kim, Wooseok Song, Sung Myung, Sun Sook Lee, Jongsun Lim, Sang Don Bu, Ki-Seok An,
  Adv. Mater. 2016.
  DOI: 10.1002/adma.201604500