Chinese and U.S. researchers have developed a small metallic tab that, when attached to the body, is capable of generating electricity from bending a finger and other simple movements.
Searching for a power outlet may soon become a thing of the past. Instead, devices will receive electricity from the tab, triboelectric nanogenerator.
The researchers' study, published online recently in the journal Nano Energy, describes the tab as being 1.5 centimeters long, by 1 centimeter wide. It delivered a maximum voltage of 124 volts, a maximum current of 10 microamps and a maximum power density of 0.22 milliwatts per square centimeter. That is not enough to quickly charge a smartphone, however, it lit 48 red LED lights simultaneously.
Triboelectric charging occurs when certain materials become electrically charged after coming into contact with a different material. Most everyday static electricity is triboelectric, according to the collaborative research led by University at Buffalo (UB) and Institute of Semiconductors (IoP) at Chinese Academy of Sciences (CAS).
"No one likes being tethered to a power outlet or lugging around a portable charger. The human body is an abundant source of energy. We thought: 'Why not harness it to produce our own power?'" lead author Qiaoqiang Gan, associate professor of electrical engineering in UB's School of Engineering and Applied Sciences, was quoted as saying in a news release.
The tab that the research team is developing addresses both concerns of the difficulty of manufacture and cost-effectiveness.
It consists of two thin layers of gold, with polydimethylsiloxane (PDMS), a silicon-based polymer used in contact lenses, Silly Putty and other products, sandwiched in between.
Key to the device is that 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 another lead author, Yun Xu, professor of IoP at CAS.
The team also plans to use larger pieces of gold, which when stretched and folded together are expected to deliver even more electricity.
Next, researchers are working to develop a portable battery to store energy produced by the tab, according to the news release. They envision the system serving as a power source for various wearable and self-powered electronic devices.
