Nanotechnology Now - Press Release: Improving the efficiency of nanogenerators that harvest static electricity

Abstract: Triboelectric energy is the scientific term for static electricity, or the energy that is created when two surfaces rub against each other. Electrons are exchanged between the two surfaces, charging one of the surfaces after they are separated. For example, if a balloon is rubbed against hair, it will cling to a wall. Or if clothes in the dryer rub together, you may see sparks as you pull them apart. Triboelectric generators are mechanical energy harvesters that can generate electricity from two surfaces rubbing against each other. These tiny power generators can be used to power wearable electronic devices, sensors, and other advanced technologies.

In a new paper, researchers theorize a new way to design triboelectric nanogenerators with a constant inherent capacitance. Currently, these nanogenerators use a time-dependent inherent capacitance, but research suggests that this change could increase their energy conversion efficiency.

The paper was published on October 26 in Nano Research.

�Triboelectric nanogenerators can provide a feasible way to convert mechanical energy into electricity,� said Youfan Hu, a professor at the School of Electronics at Peking University in China. �With improved efficiency and sensitivity, even very weak mechanical energy �hidden� in the environment can be caught and utilized.�

Capacitance is the ability of the nanogenerator�s capacitor to store electric charges. To prove that the constant inherent capacitance could work, researchers first developed a mathematical model to analyze the potential of the triboelectric nanogenerators with constant inherent capacitance. Then the researchers fabricated a version of the nanogenerator in order to test its efficiency and compare it to existing time-dependent inherent capacitance.

The capacitors were charged using three different styles of power conditioning circuits to test the performance of the two different triboelectric nanogenerators. They found that both triboelectric nanogenerators worked better on a full wave power circuit, but that the constant inherent capacitance triboelectric nanogenerators were able to store approximately two times the charge as the time-dependent inherent capacitance triboelectric nanogenerators. This gives the constant inherent capacitance triboelectric nanogenerators a big advantage. They also found that this form of nanogenerator could charge very quickly.

�The results of our study show that triboelectric nanogenerators with a constant capacitance design are more efficient for harvesting mechanical energy from the environment and delivering the load,� said Hu.

Finally, to prove how this type of triboelectric nanogenerator could be used in a real-world application, researchers create an anemometer based on their technology. An anemometer measures wind speed and direction. When the kinetic energy of the wind moved the cups on the anemometer, the triboelectric nanogenerator was able to turn that information into electric signal , which could be processed as the measurements of the wind speed. The anemometer was able to process the information in real-time and send it to the researchers.

This style of triboelectric nanogenerator is also easy to manufacture and easy to design, so looking ahead, researchers will be studying how to make the device even more practical so it can be applied to a wide range of devices. They will also study how to improve its efficiency even more. �The next step is to miniaturize the device and optimize the power management circuits. Ultimately, triboelectric nanogenerators will be able to serve in an integrated electronic system with a small footprint,� said Hu.

Other contributors include Lanyue Gan, Xijun Jiang, and Yuxuan Liu of the Hunan Institute of Advanced Sensing and Information Technology at Xiangtan University; Fan Xia of the Key Laboratory for the Physics and Chemistry of Nanodevices at Peking University; Panpan Zhang at the School of Mechanical Engineering at Shanghai Jiao Tong University; and Simiao Niu at the Department of Biomedical Engineering at Rutgers University.

The National Natural Science Foundation of China and the High-performance Computing Platform of Peking University supported this research.

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About Nano Research

Nano Research is a peer-reviewed, international and interdisciplinary research journal, publishes all aspects of nano science and technology, featured in rapid review and fast publishing, sponsored by Tsinghua University and the Chinese Chemical Society. It offers readers an attractive mix of authoritative and comprehensive reviews and original cutting-edge research papers. After 15 years of development, it has become one of the most influential academic journals in the nano field. In 2022 InCites Journal Citation Reports, Nano Research has an Impact Factor of 10.269 (9.136, 5 years), the total cites reached 29620, ranking first in China's international academic journals, and the number of highly cited papers reached 120, ranked among the top 2.8% of over 9000 academic journals.

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