A group of Korea Advanced Institute of Science and Technology (KAIST) researchers explored how the attractive physical features of zinc oxide (ZnO) materials could be more effectively used to tap into abundant mechanical energy sources to power micro devices.
The team discovered that inserting aluminum nitride insulating layers into ZnO-based energy harvesting devices led to a significant improvement of the devices’ performance.
“Mechanical energy exists everywhere, all the time, and in a variety of forms – including movement, sound and vibration. The conversion from mechanical energy to electrical energy is a reliable approach to obtain electricity for powering the sustainable, wireless and flexible devices – free of environmental limitations,” explained Giwan Yoon, a professor in the Department of Electrical Engineering at KAIST.
Piezoelectric materials such as ZnO, as well as several others, have the ability to convert mechanical energy to electrical energy, and vice versa.
Flexible ZnO-based micro energy harvesting devices, aka “nanogenerators,” can essentially be comprised of piezoelectric ZnO nanorod or nanowire arrays sandwiched between two electrodes formed on the flexible substrates. In brief, the working mechanisms involved can be explained as a transient flow of electrons driven by the piezoelectric potential.
The group’s findings are expected to provide an effective approach for realizing highly energy-efficient ZnO-based micro energy harvesting devices. “This is particularly useful for self-powered electronic systems that require both ubiquity and sustainability – portable communication devices, healthcare monitoring devices, environmental monitoring devices and implantable medical devices,” said Yoon.
