CityU New Droplet-Based Electricity Generator: A Drop of Water Lights Up 100 Small LED Bulbs
martyb writes:
CityU new droplet-based electricity generator: A drop of water lights up 100 small LED bulbs:
A research team led by scientists from City University of Hong Kong (CityU) has recently developed a new form of droplet-based electricity generator (DEG).
[...] The research was led by Professor Wang Zuankai from CityU's Department of Mechanical Engineering; Professor Zeng Xiaocheng from the University of Nebraska-Lincoln, US; and Professor Wang Zhonglin, Founding Director and Chief Scientist at the Beijing Institute of Nanoenergy and Nanosystems of Chinese Academy of Sciences.
[...] Professor Wang pointed out that there are two crucial factors for the invention. First, the team found that the continuous droplets impinging on PTFE[*], an electret material with a quasi-permanent electric charge, provides a new route for the accumulation and storage of high-density surface charges. They found that when water droplets continuously hit the surface of PTFE, the surface charge generated will accumulate and gradually reach saturation. This new discovery has helped to overcome the bottleneck of the low-charge density encountered in previous work.
[...] The device consists of an aluminium electrode and an indium tin oxide (ITO) electrode with a film of PTFE deposited on it. The PTFE/ITO electrode is responsible for the charge generation, storage, and induction. When a falling water droplet hits and spreads on the PTFE/ITO surface, it naturally "bridges" the aluminium electrode and the PTFE/ITO electrode, translating the original system into a closed-loop electric circuit.
With this special design, a high density of surface charge can be accumulated on the PTFE through continuous droplet impinging. Meanwhile, when the spreading water connects the two electrodes, all the stored charges on the PTFE can be fully released for the generation of electric current. As a result, both the instantaneous power density and energy conversion efficiency are much higher.
"Our research shows that a drop of 100 microlitres [1 microlitre = one-millionth litre] of water released from a height of 15 cm can generate a voltage of over 140V, and the power generated can light up 100 small LED lights," said Professor Wang.
[*] PTFE - Polytetrafluoroethylene, also known as Teflon(R)
The report contains a link to a small video showing the device at work.
Journal Reference:
Wanghuai Xu, et al. A droplet-based electricity generator with high instantaneous power density. Nature, 2020; (DOI: 10.1038/s41586-020-1985-6)
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