The joint team from the University at Buffalo and Institute of Semiconductors (IoP) at Chinese Academy of Science (CAS) have developed the nanogenerator using two thin layers of gold, with polydimethylsiloxane (also called PDMS, a silicon-based polymer used in contact lenses, Silly Putty and other products) in between.
Key to the device is that one layer of gold is stretched, causing it to crumple upon release. When a 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 Dr Yun Xu, professor of IoP at CAS and co-author of a paper describing the technology.
The prototype generator is 15mm long by 10mm wide and delivers a maximum voltage of 124V. Other wearable power sources such as piezoelectric have a much lower voltages. This generator also has a maximum power density of 0.22 mW/cm2 which was enough to light 48 red LED lights simultaneously.
The structure is easily manufactured, and a team of UB undergraduates is developing generators with larger pieces of gold, which when stretched and folded together are expected to deliver more power.
Researchers are also working on developing a portable battery to store energy produced by the generator to serve as a power source for various wearable and self-powered electronic devices.