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Friction device converts hair frizz to electricity

Hair’s static-electric properties make it an ideal electrode material for triboelectric generators

by Mitch Jacoby
April 16, 2018 | A version of this story appeared in Volume 96, Issue 16

These images show the microstructure of a human-hair paste applied to an electrode and that electrode wired into a working triboelectric generator as it lights up a string of LEDs.
Credit: ACS Sustainable Chem. Eng.
An alkaline film of human hair applied to a transparent electrode (left) and wired into a triboelectric generator readily lights up a string of red LEDs.

The same properties that cause hair to become frizzy and flyaway on dry winter days make the material a low-cost choice for generating power (ACS Sustainable Chem. Eng. 2018, DOI: 10.1021/acssuschemeng.8b00136). So-called triboelectric generators convert friction to electricity by capturing energy released when paired surfaces that attract opposite charges move past one another. Recently, researchers have demonstrated that these renewable-energy devices can be incorporated into clothing, walkways, and other familiar objects and thereby power cell phones and other electronics through vibrations and ordinary human motion. A variety of common synthetic materials often serve as the negative side of these circuits. But few positive materials are known. A team led by Jang-Kun Song of Sungkyunkwan University demonstrated that hair readily fills that need. The researchers treated human hair with alkaline ethanol solution, then applied the resulting paste as a micrometer-thick film to indium tin oxide electrodes using various low-tech deposition methods. They paired those positive electrodes with negative counterparts coated with a polyimide film and measured the output produced by tapping on the devices. Proof-of-concept evaluations showed that tapping on the generators a few times produced enough power to brightly illuminate a string of light-emitting diodes, which require just a small fraction of the power needed to light up an ordinary household lightbulb. The devices showed little performance deterioration even after three months of open-air storage.


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