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."
Microbial fuel cells create energy when bacteria break down organic material producing a charge that is transferred to the anode. Logan, who has studied microbial fuel cells for more than ten years, usually looks to wastewater as a source for both the organic material and the bacteria to create either electricity or hydrogen, but these tiny machines are a bit different.
"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 that pure 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.
A'ndrea Elyse Messer | EurekAlert!
Silicon solar cell of ISFH yields 25% efficiency with passivating POLO contacts
08.12.2016 | Institut für Solarenergieforschung GmbH
Robot on demand: Mobile machining of aircraft components with high precision
06.12.2016 | Fraunhofer IFAM
Physicists of the University of Würzburg have made an astonishing discovery in a specific type of topological insulators. The effect is due to the structure of the materials used. The researchers have now published their work in the journal Science.
Topological insulators are currently the hot topic in physics according to the newspaper Neue Zürcher Zeitung. Only a few weeks ago, their importance was...
In recent years, lasers with ultrashort pulses (USP) down to the femtosecond range have become established on an industrial scale. They could advance some applications with the much-lauded “cold ablation” – if that meant they would then achieve more throughput. A new generation of process engineering that will address this issue in particular will be discussed at the “4th UKP Workshop – Ultrafast Laser Technology” in April 2017.
Even back in the 1990s, scientists were comparing materials processing with nanosecond, picosecond and femtosesecond pulses. The result was surprising:...
Have you ever wondered how you see the world? Vision is about photons of light, which are packets of energy, interacting with the atoms or molecules in what...
A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.
Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...
In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.
“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...
16.11.2016 | Event News
01.11.2016 | Event News
14.10.2016 | Event News
09.12.2016 | Life Sciences
09.12.2016 | Ecology, The Environment and Conservation
09.12.2016 | Health and Medicine