Scientists have discovered that spit can be used to power small electronic devices – although the future isn’t going to involve us having to spit on our gadgets when they’re low on power.
The tiny fuel cell collects energy and can power equally small devices, the creators from Penn State University, US, say.
Potential uses include being able to predict when women are going to ovulate, days before they start.
“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.
They don’t produce much energy but they can produce enough to run on-chip applications.
The scientists said that one use for the technology could be in a tiny ovulation predictor – which would be based on the conductivity of a woman’s saliva. The saliva in a woman’s mouth changes five days before ovulation.
The device would measure the conductivity of the saliva in the mouth while also using it as a power source and send the reading to a nearby mobile phone.
In theory the chip could be used to collect and report data on the health of those who use it. The researchers said the fuel cell can be powered with any liquid that has enough organic material, which opens the door for wider applications of the technology.
“There is a lot of organic stuff in saliva.”
The microbial fuel cells, which are made up of saliva input ports, an anode, cathode and a chamber, create energy when bacteria break down organic material. This produces a charge that is transferred to the anode in the device.
The researchers usually look to wastewater as a source for both the organic material and the bacteria to create either electricity or hydrogen. However theses latest cells work differently.
Bruce E. Logan from the University said: “There is a lot of organic stuff in saliva.”
He continued: “We have previously avoided using air cathodes in these systems to avoid oxygen contamination with closely spaced electrodes.”
“However, these micro cells operate at micron distances between the electrodes. We don’t fully understand why, but bottom line, they worked.”