Researchers have developed a metallic tab which, when connected to a human body, is capable of generating electricity from bending a finger and other simple movements. According to a research project led by the University at Buffalo, New York, and Institute of Semiconductors (IoP) at the Chinese Academy of Science (CAS), the tab -- a triboelectric nanogenerator -- can convert mechanical energy into electrical energy for electronic devices.
"The human body is an abundant source of energy. We thought: 'Why not harness it to produce our own power?'" said lead author Qiaoqiang Gan, associate professor at the University at Buffalo. The tab was detailed in the journal Nano Energy.
Triboelectric charging occurs when certain materials become electrically charged after coming into contact with a different material. Most everyday static electricity is triboelectric. The tab consists of two thin layers of gold, with polydimethylsiloxane (also called PDMS -- a silicon-based polymer used in contact lenses, Silly Putty and other products) sandwiched in between.
One layer of gold is stretched, causing it to crumple upon release and create what looks like a miniature mountain range. When that force is reapplied, for example, from a finger bending, the motion leads to friction between the gold layers and PDMS. "This causes electrons to flow back and forth between the gold layers. The more friction, the greater the amount of power is produced," said Yun Xu, professor at the IoP.
The study described a small tab (1.5 centimetres long, by one centimetre wide). It delivered a maximum voltage of 124 volts, a maximum current of 10 microamps and a maximum power density of 0.22 millwatts per square centimetre.
That is not enough to quickly charge a smartphone, but it lit 48 red LED lights simultaneously. The team is planning to use larger pieces of gold, which when stretched and folded together are expected to deliver even more electricity.
The researchers are also working on developing a portable battery to store energy produced by the tab. They envision the system serving as a power source for various wearable and self-powered electronic devices.