Engineers at Pennsylvania State University have engineered a tiny generator fueled by saliva in hopes of creating sensors for glucose monitoring in diabetics.

Microbial fuel cells create energy when bacteria break down organic material. This breakdown produces a charge that is transferred to a node. Professor Bruce E. Logan of Penn State has been studying these microbial fuel cells for more than 10 years.

Normally researchers look at waste water for a source of organic material and bacteria that is used to create electricity or hydrogen. However, these generators are different. They can produce 1 microwatt of energy through saliva.

Biomedical devices that use microbial fuel cells are portable and would have an energy source available anywhere. Although saliva does not have the natural bacteria needed for these fuel cells, manufacturers would need to inoculate them with the bacteria in order for them to function correctly.

Any liquid material with sufficient organic material would be able to power these fuel cells, not just saliva.

Researchers hope to use these new devices in different ways, such as using a woman’s saliva in order to predict her ovulation. This tiny generator would test the conductivity of her saliva, which changes five days before ovulation.