Using the principle of triboelectricity, researchers have found a relatively simple and optimal way to generate electric charge. The breakthrough could provide a way to power wearables and other devices without batteries.
In the field of clean energy power generation, triboelectricity is a relatively unknown field. It's basically the same thing as static electricity - energy is created through friction when two surfaces rub or pull apart. While this approach cannot generate large amounts of electricity and will therefore never replace wind, solar, geothermal and other green energy initiatives, it could find a place in smaller applications such as medical devices and wearable technology.
In fact, triboelectricity has been used to develop sensors for detecting mercury levels in food; tree-mounted devices for monitoring forest fires that can detect carbon monoxide and temperature changes; and special yarns that can turn any fabric into a micro-power plant. Researchers at the University of Alabama have even created an inexpensive triboelectric generator using double-sided tape and plastic film.
Now, a team of researchers from Brussels, Australia and Hong Kong has uncovered another secret to the effectiveness of the triboelectric effect. After experiments with a range of materials, the scientists created nanoscale plastic beads using melamine and formaldehyde. They then found that the size of the hybrid beads was key to the success of efficient triboelectric energy generation.
Specifically, they found that larger beads tended to have a negative charge, while smaller beads tended to have a positive charge. By designing a system called a triboelectric nanogenerator (TENG), with smaller beads on one side of the film and larger beads on the other, they say it can output more electricity than other triboelectric methods are typically capable of. This includes methods that rely on rubbing two rough surfaces to create an electric charge. It should be noted that the current output measured during the experiment was only in nanoamps, so we don't need to get too excited.
The beads don't rub against each other, which also means they last longer, with tests showing they can withstand 10,000 cycles. The researchers also say the beads can be produced without the use of solvents, making them cheaper to manufacture, and when they wear out they can be renewed with just a coat of powder.
"Our study shows that small changes in material selection can significantly improve energy production efficiency," said the study's lead author Ignaas Jimidar of the Université Libre de Bruxelles. "This opens up new possibilities for triboelectric nanogenerators to be used in daily life, without relying on traditional energy sources."
The findings have been detailed in a paper published in the journal Small.