Harnessing a principle known as triboelectrification, researchers have worked out the optimal way to generate an electrical charge in a relatively simple way. The breakthrough could provide a battery-free way to power wearables and other devices.
In the world of clean power generation, triboelectrification is a relatively unknown player. It's basically the same thing as static electricity – the generation of energy through friction when two surfaces rub up against each other, or are pulled apart. While the method will never replace wind, solar, geothermal and other green energy initiatives because of its inability to generate serious power, it could have a home in smaller applications such as medical devices and wearable tech.
In fact, triboelectrification has already been used to develop a sensor for detecting mercury in foods; a tree-mounted device that can detect carbon monoxide and temperature changes to monitor forest fire outbreaks; and a special yarn that can turn any fabric into a mini power plant. Researchers at the University of Alabama have even created an inexpensive triboelectric generator out of double-sided tape and plastic film.
Now, a team of researchers from Brussels, Australia, and Hong Kong has unlocked another secret to the effectiveness of the triboelectric effect. After experimenting with a range of materials, the scientists created nano-sized plastic beads made from melamine and formaldehyde. They then discovered that mixing the sizes of the beads was the key to the success of efficient triboelectric energy generation.
Specifically, they discovered that larger beads tended to acquire a negative charge while smaller ones tended to become positively charged. By designing a system known as a triboelectric nanogenerator (TENG) with the smaller beads on one side of a thin film and the larger ones on the other, they say it was able to output more electricity than would typically be possible by other triboelectric means. That includes methods that rely on rubbing two rough surfaces together to generate a charge. It should be noted that the current output measured during the experiments was only registered in nanoAmps, so let's not get too excited.
The fact that the beads aren't scraped against each other also means that they can last longer, with testing showing that they could survive 10,000 cycles. The researchers also say the beads can be produced without the use of solvents, making them cheaper to manufacture, and that they can be renewed with a simple coating of powder when they do wear out.
"Our research shows that small changes in material selection can lead to significant improvements in energy generation efficiency," said study lead author Ignaas Jimidar from Vrije Universiteit Brussels. "This opens up new possibilities for triboelectric nanogenerators in everyday life, without reliance on traditional energy sources."
The findings have been detailed in a paper published in the journal Small.
Source: Vrije Universiteit Brussels
