We demonstrate a practical and efficient hybrid triboelectric-piezoelectric energy harvesting structure that consists of a nanopatterned and/or metal-deposited polymer film and a piezoelectric elastomeric sponge. When a polymer (here, polycarbonate (PC)) and an elastomer (here, polydimethylsiloxane (PDMS)) make contact with and detach from each other, triboelectric energy can be harvested. In this case, the PC surface can be nanopatterned by continuous dynamic nanoinscribing and/or coated by a metal (here, Cu) layer for enhanced performance. When a piezoelectric material (here, lead zirconate titanate (PZT)) and sugar powder are mixed with PDMS, and the sugar is later dissolved, a porous piezoelectric elastomeric sponge (PES) can be fabricated. When a PC film and a PES make contact with and detach from each other, both triboelectric and piezoelectric energies can be simultaneously harvested. We systematically study the effect of PES and Cu thicknesses and dynamic nanoinscribed nanopattern on the energy harvesting performance of the hybrid triboelectric–piezoelectric nanogenerator (HTPENG). The performance of the HTPENG can be improved by using the PES of optimal thickness, and by applying the nanopattern and Cu layer. The HTPENG can be utilized in many systems where wireless self-powering is desired, such as wearable devices, flexible sensors, and skin electronics.

In this study, we demonstrated a triboelectric nanogenerator composed of a vertical column, and a cylindrical shell, for omnidirectional wind energy harvesting. With a simple structure using a metal wire, the height between the two triboelectric materials can be maintained, and the Al coated shell can also be electrically connected to the electrode. When the shell is deformed by wind, its Al layer and Polytetrafluoroethylene (PTFE) on the outside of the column can be triboelectrically charged. Thus, wind energy can be harvested through a triboelectric energy conversion mechanism. In particular, due to the high flexibility of the shell, the nanogenerator operates even at wind speeds as low as 1 m/s. Although the output voltage is asymmetrical depending on the wind direction due to the metal wire, it was experimentally confirmed that the device can harvest wind energy from all directions. The measured output RMS power was approximately 15 μW at a wind speed of 6 m/s.