Page 44 - EngineerIT March 2022

INDUSTRY, TECHNOLOGY, PRODUCTS AND INNOVATION

Portable generator – Shaken but not stirred

new stick-like, water-based device can convert energy
from movement into electricity. The technology, which
w
A as reported in the journal Science and Technology of
Advanced Materials, could be used to power portable devices, such
as safety lights.
With the growing interest in the internet of things and small
electronics, there is high demand for portable energy sources. One
way to produce power is to harvest energy from the environment,
such as thermal, solar or mechanical energy. To capture mechanical
energy – the power an object gets from its position and motion –
scientists have developed triboelectric nanogenerators, which can
produce electricity through friction.
“Triboelectric nanogenerators are one of the most effective
tools for harvesting mechanical energy because of their high
electrical output, low cost and easy accessibility,” says Professor
Sangmin Lee of Chung-ang University in the Republic of Korea.
Triboelectric generators are electrically charged when two
dissimilar materials touch and then separate. For example, when
a balloon is rubbed on clothing, the balloon becomes charged transferred to the electrodes to generate a high electrical output.
and can stick to things. However, friction between two materials “Because of its simple mechanism and design, this small and
inevitably causes damage, reducing device lifespan. lightweight device could be used in everyday life. Electrical power
Using liquids can reduce friction, but liquid-based generators can be produced simply by pouring water into the generator then
have a considerably lower electrical output than solid ones. There giving it a shake,” explains Lee.
is also a trade-off between making the device large enough for the The researchers tested different designs, changing the size and
liquid to move and generate electricity, while also ensuring it is ratio of the electrodes, the physical space between the electrodes
compact enough to be portable. and the amount of water in order to determine the optimal
To overcome these problems, researchers at Chung-ang combination. They found that the portable stick generator could
University, together with colleagues in South Korea and the US, generate a high electrical output reaching 710 volts when it had
developed a lightweight, compact, water-based generator that can adequate space for water movement and a high electrode area.
produce electrical power when shaken. The researchers showed that the generator can power 100 LED
The device has a simple stick-like design and consists of 10ml lights, meaning it could be used as a traffic safety light baton that
of water, a polymer cylinder and electrodes. The container’s illuminates when shaken. This study demonstrates the potential
polymer material is negatively charged. The water moves up and for triboelectric nanogenerators to be used for a wide range of
down when the device is shaken, acquiring a positive charge that is everyday applications.

Send technical and news articles to

engineerit@nowmedia.co.za

EngineerIT | March 2022 | 42