Researchers have designed a triboelectric nano-generator that uses friction generated from body movements to produce electricity. It consists of two thin layers of gold, with polydimethylsiloxane (PDMS, a silicon-based polymer used in contact lenses) sandwiched in between. One of the gold layer is stretched causing it to crumple upon release. When a force is applied, say by movement of the finger, friction is generated between the gold layers and PDMS. This causes electrons to flow between the two gold layers, generating electricity.
A tiny wearable electricity generator
The nano-generator is only 1.5 centimetres long, by 1 centimetre wide. It delivered a maximum voltage of 124 volts, a maximum current of 10 micro-amperes and a maximum power density of 0.22 mill-watts per square centimetre. That’s not enough to quickly charge a smartphone; however it lit 48 red LED lights simultaneously.
The researchers believe that improving the efficiency and performance of the nano-generator will enable charging smart wearable devices in the near future. Because the tab is easily fabricated, the team plans to use larger pieces of gold, which when stretched and folded together are expected to deliver even more electricity. They also want to develop a portable battery that can store energy generated by this nano-generator.
This is not the first time that a nano-generator was used to generate triboelectricity from friction. Previously, generators were designed to produce electricity from rolling tyres. In this case friction was between the tyres and the surface on which it was rolling. Other researchers have proposed numerous nano-generators that utilise the triboelectric effect. However, most are difficult to manufacture (requiring complex lithography) or are not cost effective. The nano-generator designed in the current study addresses both of those concerns.