Researchers at the Indian Institute of Technology (IIT) Delhi, have designed and fabricated a device that can generate electricity from raindrops, water drops, water streams and even ocean waves. The device can do so by using a method called “triboelectric effect” and “electrostatic induction”. Called “Liquid-solid Interface Triboelectric Nanogenerator”, the electricity generated by the device can be stored in batteries for further use.
The device has a very simple structure consisting of specially designed nanocomposite polymers and contact electrodes, a news release from IIT Delhi explains. It can generate a few Milliwatt (mW) of power, which is sufficient to power small electronic devices such as watches, digital thermometers, radio frequency transmitters, healthcare sensors and pedometers. When compared to conventional methods, such as the use of the piezoelectric effect, this device can generate significantly more electricity, the release explains.
Professor Neeraj Khare, from the department of physics at IIT Delhi, and his group at the Nanoscale Research Facility (NRF), have been working on harvesting electrical energy from wasted mechanical vibrations using the triboelectric effect. The group has also filed an Indian patent on the various aspects of the use of ferroelectric polymer for harvesting mechanical energy including the current device, the release adds.
Khare says the “triboelectric effect” has been a known phenomenon for a long time. “In this effect, charges are generated when two surfaces are in friction. The best example we see are sparkling lights when we move blankets, jackets. It is only lately that it has been extensively investigated as a practical alternative for energy harvesting,” Khare explains in the release.
The findings of the research were recently published in the journal Advanced Materials Interfaces, where the team demonstrated that water drops rolling over the surface of the device generates electricity. The research was also supported by the Ministry of Electronics and Information Technology (MeitY) and the Department of Science and Technology (DST), under the NNetRA project.
The researchers successfully incorporated nanostructures into a polymer matrix, which enhanced the film's surface roughness, polarizability, and hydrophobicity, among other characteristics, as a result, the release explains. The flexible film is used to fabricate the device where raindrops just have to slide down and generate electricity as a result. The artificially created rough surface allows it to generate more charge and superhydrophobic properties of the solid surface help to roll the water drop without getting stuck to the surface.
The research team was also able to find that saline water drops generated more electricity. The researchers also showed that the device can even work with ocean waves, where the water is saline.