Engineers at the University of Alberta have discovered a new method of producing electricity for self-powered sensors and portable electronics.
A couple of months ago, we covered the story of a WSU doctoral student who forgot to turn the light off in the lab and the serendipitous discovery that ensued.
This time, however, another student from a different university, working on a sample, forgot to turn the power button on, only to notice an unexpected effect.
Triboelectricity: Electrification by Friction
Run a comb through your hair, then bring it close to small bits of paper, you’ll see that the pieces get attracted by the comb. This is what is called electrification.
Electrification is the transfer of electrons from one material to another by means of friction or contact, and depending on their natures, one becomes positively charged, the other negatively.
Triboelectricity, from the Greek “tribo” which means “to rub”, refers to the electrostatic phenomenon created by the friction of two materials of different nature.
Electrons on the surface of one of the two materials are transferred to each other and this charge remains after the end of friction.
Nanogenerators, tiny energy-harvesting devices, are suggested as a solution to provide continuous power to portable electronics, smart wearables, medical implants and other remote monitoring devices.
One of these types of nanogenerators are TENG’s (triboelectric nanogenerators), which are based on the phenomenon of triboelectrification and electrostatic induction.
“Accidentally” Breaking New Ground for Nanogenerators
Scientists have been working on different triboelectric nanogenerators in recent years, but the TENG’s they built shared one shortcoming: the devices only produce a low-density alternating (AC) current.
Now, Jun Liu, a Ph.D. student at the University of Alberta, accidentally found a way to produce a high-density DC current, which has never been achieved before.
Under the mentorship of Thomas Thundat, a professor of chemical engineering, Liu was using a special microscope for research unrelated to nanogenerators.
Before leaving the lab, Liu forgot to apply electricity to the sample he was working on but it somehow still emitted a current.
After ruling out some theories like an anomaly, a glitch, or interference, Liu eventually found that the friction between the material sample and the microscope’s probe was the cause.
What adds to the importance of this discovery is that the electricity generated flowed in a steady direct current.
“The discovery means that nanoscale generators have the potential to harvest power for electrical devices based on nanoscale movement and vibration: an engine, traffic on a roadway—even a heartbeat. It could lead to technology with applications in everything from sensors used to monitor the physical strength of structures such as bridges or pipelines, the performance of engines or wearable electronic devices.”
A paper on the findings was published in the journal Nature Nanotechnology.