22-02-2019 | By Rob Coppinger
Triboelectrics is the generation of electricity from friction and it could become a new power source for electronic devices.
The friction could be as simple as a finger swiping across a smartphone’s glass screen, walking, the friction of shoe upon pavement, or friction between textile fibres, and they could all become sources of power. People experience the shock of this static electricity in their everyday lives as the charge they build up through friction is discharged. Research has determined that this electric charge is generated from friction between the surfaces of dissimilar materials which affects their atoms’ electrons. The affected atoms’ electrons change position and form a dipole, inducing an electric field.
A dipole is a pair of positive and negative charges of equal magnitude separated by a small distance. Deformations in the atomic lattice in each surface during friction contributes to the electric charge transfer. It is an asymmetry in the two materials’ respective dipoles and their induced polarisation and fields which is why one surface will always transfer its charge to the other. Magnesia and barium titanate have been used by researchers for the two dissimilar materials needed to examine this interaction, to better understand how surfaces respond when they come into contact.
“When we will understand how the whole mechanism works and the process works and we can figure out how to make a better pair, a triboelectric pair, what gives us the best harvesting efficient that we can use for our phone, shoes or the fibres, so we can weave it; we can engineer any [triboelectric] material we want,” says James Chen, an assistant professor in the University at Buffalo’s department of mechanical and aerospace engineering.
These images show how the surfaces of magnesia (top block) and barium titanate (bottom block) respond when they come into contact with each other. The resulting lattice deformations in each object contributes to the driving force behind the electric charge transfer during friction. Credit: James Chen, University at Buffalo.
The next step, according to Chen, is to use machine learning techniques, “to understand, to marry the experiments and the theory to create a [triboelectric] harvesting system. Hopefully we can get it done in a few years.”. His ideas were put through computer models and compared with the results of experiments elsewhere. His team’s research has involved a range of disciplines, from electrical engineering to solid and contact mechanics and materials science.
The Georgia Institute of Technology (Georgia Tech), in the United States’ state of Georgia, has conducted physical experiments and is developing triboelectric nanogenerators which can harvest static electricity. “We are trying to work something out together,” Chen says of the potential co-operation between Buffalo and Georgia Tech. “We are trying to push this technology forward, to understand this phenomena, so we can move this technology forward.”
Georgia Tech researchers have used triboelectric nanogenerator devices for charging molecules being analysed to increase the sensitivity of a chemical analysis technique. Chen’s work is supported by a $400,000 United States government National Science Foundation grant, funding which lasts until next year. Chen will present his findings at the American Physical Society’s meeting in Boston, Massachusetts.