Static electricity is not fatal but it can carry a high voltage that goes up to tens of thousands of volts. Triboelectricity, an electric charge generated by friction, is produced when two solid surfaces come in contact with one another. However, scientists have noted that it is generated even when liquids come in contact with solids. The amount of electricity generated is much lower than that generated during solid-solid contact.
Professor Dongwhi Choi and his team from Kyung Hee University, South Korea, attempted to address this problem by developing a more stable technique of injecting electrical charges into a polymer material, which enhances the conventional energy generation. Their research paper was published under the title of “Monocharged Electret based Liquid-Solid Interacting Triboelectric Nanogenerator, for its Boosted Electrical Output Performance.’”
“Basically, it is a platform of collecting triboelectricity generated by moving drops of liquid on energy harvesting devices,” explained Choi. “Much research in the past demonstrated that introducing nanoscales on the device increases the triboelectricity generation. The problem was that nanoscales are not easy to create and that they make the device opaque. The liquid-solid contact makes a good application for transparent objects, which is an advantage that creating nanoscales can hardly contribute to.”
His team experimented with surface topography, hypothesizing that artificially injecting electrical charges instead of introducing nanoscales would increase energy generation. The outcome was an unprecedented amount of energy.
It’s one of the first researches in the world that registered success in demonstrating changes in energy levels when liquid and solid come in contact with each other. It implies that we are a step closer to self-powered sensors and flexible energy harvesters.
Sunmin Jang, a graduate student and member of this team, said: “Previously pure distilled water was considered to be the best medium for the liquid-solid contact triboelectrification, since impurities in the water hindered the process. In other words, the energy output level of tap water, rainwater, or seawater was deemed too low to be practical. Our research solved this problem, it seems that we can use any water commonly existing around us for energy harvesting.”
The platform is apt to be used as a sensor since solutions generate different amounts of electric current in relation to concentration. Conversely, the harvester produced by this team works as a sensor that detects a solution’s concentration.
Its transparency makes it an ideal choice for photovoltaic panels that harvest energy during rainfall. It will also help in creation of transparent and flexible devices.
“Inserting electric charges is not necessarily a novel idea, and the fabrication process is relatively simple. In a nutshell, it is highly practical,” said Choi. “Moreover, this conventional technique generates a great amount of energy when combined with typical polymers, promising great application opportunities.”