For electricity, pour water and shake it.

Shaking the small, light device generates enough energy to power 100 LEDs.

A new stick-like, water-based device can convert movement energy into electricity. The research, published in the journal Science and Technology of Advanced Materials, could be used to power portable devices such as safety lights.

The growing popularity of the Internet of Things and small electronics has resulted in a high demand for portable energy sources. Harvesting energy from the environment, such as thermal, solar, or mechanical energy, is one method of producing power. To capture mechanical energy – the power derived from an object’s position and motion – scientists created triboelectric nanogenerators, which can generate 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 ease of access,” explains mechanical engineer Sangmin Lee of the Republic of Korea’s Chung-ang University.

When two dissimilar materials touch and then separate, triboelectric generators become electrically charged. When a balloon is rubbed against clothing, it becomes charged and can stick to things. Friction between two materials, on the other hand, inevitably causes damage, reducing device lifespan.

Although using liquids reduces friction, liquid-based generators produce significantly less electricity than solid-state generators. There is also a trade-off between making the device large enough for the liquid to move and generate electricity while remaining portable.

To address these issues, Lee and colleagues in South Korea and the United States created a lightweight, compact water-based generator that can generate electrical power when shaken.

The device is made up of 10ml of water, a polymer cylinder, and electrodes and has a simple stick-like design. The polymer material used to make the container is negatively charged. When the device is shaken, the water moves up and down, accumulating a positive charge that is transferred to the electrodes, resulting in a high electrical output.

“Because of its simple mechanism and design, this small, lightweight device could be used in daily life. “Electrical power can be generated simply by pouring water into the generator and shaking it,” Lee explains.

To find the best combination, the researchers tested various designs, varying the size of the electrodes, the physical space between them, and the amount of water. They discovered that when the portable stick had enough space for water movement and a large electrode area, it could generate a high electrical output of 710 volts.

The generator can power 100 LED lights, allowing it to be used as a traffic safety light baton that illuminates when shaken, according to the researchers. This research shows that triboelectric nanogenerators have the potential to be used in a variety of everyday applications. 

For electricity, pour water and shake it. - Science at Virtual Solutions (virtualsolv.com)