Human saliva to run tiny power generators!

Soon, you can check your sugar levels or ovulation changes with bacteria-generated fuel technology powered by your spit!

According to an international team of engineers, saliva-powered, micro-sized microbial fuel cells can produce minute amounts of energy sufficient to run on-chip applications.

Microbial fuel cells create energy when bacteria break down organic material producing a charge that is transferred to the anode.

"There is a lot of organic stuff in saliva," said Bruce E. Logan, a professor of environmental engineering at Pennsylvania State University.

"By producing nearly 1 microwatt in power, this saliva-powered microbial fuel already generates enough power to be directly used as an energy harvester in microelectronic applications," fellow researcher Justine E. Mink added.

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," Mink explained.

Biomedical devices using 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, the researchers added.

The anode is 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, said the study reported in the journal Nature Publishing Group's Asia Materials.