Tiny
power generator runs on spit
Saliva-powered
micro-sized microbial fuel cells can produce minute amounts of energy
sufficient to run on-chip applications, according to an international team of
engineers.
Bruce E. Logan, Evan Pugh Professor and Kappe Professor of Environmental
Engineering, Penn State, credited the idea to fellow researcher Justine E.
Mink. "The idea was Justine's because she was thinking about sensors for
such things as glucose monitoring for diabetics and she wondered if a mini
microbial fuel cell could be used," Logan said. "There is a lot of
organic stuff in saliva."
"By producing
nearly 1 microwatt in power, this saliva-powered, micro-sized MFC already
generates enough power to be directly used as an energy harvester in
microelectronic applications," the researchers report in a recent issue of
Nature Publishing Group's Asia
Materials.
The researchers believe
that the emergence of ultra-low-power chip-level biomedical electronics,
devices able to operate at sub-microwatt power outputs, is becoming a reality.
One possible application would be a tiny ovulation predictor based on the
conductivity of a woman's saliva, which changes five days before ovulation. The
device would measure the conductivity of the saliva and then use the saliva for
power to send the reading to a nearby cell phone.
Biomedical devices
using micro-sized microbial fuel cells would be portable and have their energy
source available anywhere. However, saliva does not have the type of bacteria
necessary for the fuel cells, and manufacturers would need to inoculate the
devices with bacteria from the natural environment.
In the past, the
smallest fuel cells have been two-chambered, but this micro version uses a
single chamber with a graphene- rather than platinum-coated carbon cloth anode
and an air cathode. Air cathodes have not been used before because if oxygen can
get to the bacteria, they can breath oxygen and do not produce electricity.
"We have
previously avoided using air cathodes in these systems to avoid oxygen
contamination with closely spaced electrodes," said Logan. "However,
these micro cells operate at micron distances between the electrodes. We don't
fully understand why, but bottom line, they worked."
The anode is actually
composed of carbon nanomaterial graphene. Other microbial fuel cells used
graphene oxide, but the researchers showed thatpure multi-layered graphene can
serve as a suitable anode material.
While the researchers
tested this mini microbial fuel cell using acetate and human saliva, it can use
any liquid with sufficient organic material.
Justine E. Mink, recent
Ph.D. recipient, King Abdullah University of Science and Technology, was first
author of this paper. Also working on this project were Muhammad M. Hussain,
assistant professor, and Ramy M. Qaisi, graduate student, KAUST.
KAUST supported this
work.
Story Source:
The above story is
based on materials provided by Penn State. The original article was
written by A'ndrea Elyse Messer. Note:
Materials may be edited for content and length.
Cite This Page:
Penn State. "Tiny power
generator runs on spit." Science
Daily, 3 April 2014.
<www.sciencedaily.com/releases/2014/04/140403105814.htm>.
