Having your phone die on you when you're out is possibly one of the most frustrating first world problems of the digital era, but researchers at the University of Buffalo and the Institute of Semiconductors (IoP) at the Chinese Academy of Science (CAS) may have a solution.
The team has invented a gold-laced tab that can generate electricity from simple body movements, meaning that in the not-so-distant future, you could be charging your phone with a simple flick of the finger. The gadget, called a triboelectric nanogenerator (TENG), is described in detail in a paper published in the journal Nano Energy last month.
“No one likes being tethered to a power outlet or lugging around a portable charger," Qiaoqiang Gan, lead author and associate professor of electrical engineering in UB’s School of Engineering and Applied Sciences, explained in a statement. "The human body is an abundant source of energy. We thought: ‘Why not harness it to produce our own power?’”
Energy that is cheap, mobile, and sustainable? Check, check, and check.
The tab is made from two thin gold films separated by a strip of polydimethylsiloxane (PDMS), the same silicon-based substance used to make contact lenses and Silly Putty. One of the gold layers is stretched so that it crumples on release to form ridges reminiscent of a mountain range.
TENG uses the same physics as static electricity – during a process called the triboelectric effect, a material becomes electrically charged after coming into frictional contact with another material. In this case, bending a finger creates friction between the gold layers and the strip of PDMS, creating electricity.
“[The bending] causes electrons to flow back and forth between the gold layers. The more friction, the greater the amount of power is produced,” Yun Xu, a second lead author and professor of IoP at CAS, added.
This is not the first nanogenerator exploiting the triboelectric effect to have been invented, but it does seem to be the first to overcome two important hurdles – cost and ease of production. TENG, unlike previous attempts, is relatively inexpensive and easy to produce.
The tab is 1.5 centimeters long and 1 centimeter wide, but despite its diminutive size can deliver a max voltage of 124 volts, a maximum current of 10 microamps, and a maximum power density of 0.22 milliwatts per square centimeter. Right now, it is not enough to charge a smartphone, but it can produce enough energy to light 48 red LED lights at the same time.
Next up, the team hopes to create larger versions that can generate more energy, as well as portable batteries capable of storing the electricity produced by the tab.