A small water-based generator powers the security lights
A new stick-shaped water-based device can convert motion energy into electricity. The technology, which was reported in the review Advanced materials science and technology, could be used to power portable devices, such as security lights.
With the growing interest in the Internet of Things and small electronic devices, there is a strong demand for portable power sources. One of the ways to generate electricity is to harvest energy from the environment, such as thermal, solar or mechanical energy. To capture mechanical energy – the power an object derives from its position and movement – scientists have developed triboelectric nanogenerators, capable of generating electricity through friction.
“Triboelectric nanogenerators are one of the most efficient tools for harvesting mechanical energy due to their high electrical power, low cost, and ease of access,” says Professor Sangmin Lee of Chung University -ang 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 and can stick to objects. However, the friction between two materials inevitably causes damage, reducing the life of the device.
Using liquids can reduce friction, but liquid-based generators have considerably less electrical power than solids. There is also a trade-off between making the device large enough for liquid to move and generate electricity, while ensuring that it is compact enough to be portable.
To overcome these problems, researchers from Chung-ang University, in collaboration with colleagues from South Korea and the United States, have developed a lightweight, compact and water-based generator that can generate electricity when shaken.
The device has a simple stick-shaped design and consists of 10ml of water, a polymer cylinder and electrodes. The polymer material of the container is negatively charged. Water rises and falls when the device is shaken, acquiring a positive charge which is transferred to the electrodes to generate high electrical power.
“Due to its simple mechanism and design, this small and lightweight device could be used in daily life,” says Lee. “Electrical energy can be produced simply by pouring water into the generator and then shaking it.”
The researchers tested different designs, varying the size and ratio of the electrodes, the physical space between the electrodes, and the amount of water to determine the optimal combination. They found that the portable stick generator could generate high electrical power of up to 710 volts when given sufficient space for water movement and a high electrode area.
Researchers have shown that the generator can power 100 LED lights, meaning it could be used as a traffic safety glow stick that lights up when shaken. This study demonstrates the potential for using triboelectric nanogenerators for a wide range of everyday applications.