Harnessing sources of alternative energy has been a priority of the environmental tech world since back when the word “apps” still referred to fried mozzarella and potato skins. We’ve been incredibly resourceful, finding energy in things like dog’s fecal matter, tornadoes, and, of course, that burning ball of energy that rests in the center of our solar system. And now, we’re looking inside our own mouths.
Penn State researchers have created a small power generator that runs on human spit. There's a lot of organic stuff going on in our saliva, and this organic stuff can power microbial fuel cells. You can't get much energy this way: the fuel cells produce just one microwatt, but that’s enough to power simple on-chip applications. The fuel cell itself is a single chamber, using a graphene-coated carbon cloth anode. The energy comes from bacteria inside the cell breaking down organic spit material and releasing electrons.
This is a similar technique to what's been done with wastewater (which contains lots of organics). While saliva is only slightly less disgusting, really, it is more omnipresent for us humans. More importantly, it can be useful for biomedical electronics, such as an ovulation predictor based on the conductivity of saliva. Or, in a glucose monitor for diabetics. Of course, saliva isn’t the only liquid that can work. If it’s got organic matter in it, any liquid should work. But saliva is a little less gross than some of the other options.
Via Penn State