From Drool to Fuel

By Anna Nidhiry | Staff Writer | SQ Online (2013-14)

Start collecting drool, because it might be a new source of power. Think this sounds silly? Well, think again. Researchers at Penn State University have created a microbial cell that may be able to extract power from organic material in saliva. The amount of electricity produced by saliva may not be enough to power a home or even your phone, but it has the potential to fuel chip-level microelectronic devices, which is a breakthrough itself.

Microbial fuel cells (MFC) essentially work via a biological mechanism similar to that used by bacteria to obtain energy. In essence, it uses methods of electron transfer to remove electrons from organic material and add electrons to an electron acceptor. Through this mechanism, electrons can be transferred across a wire from an anode to a cathode to generate electricity. According to Professor Bruce E. Logan at Penn State, the organic material in saliva can be broken down by MFC’s to produce a charge.

The amount of energy produced by saliva is approximately one microwatt (one-millionth of a watt), which can hardly be considered anything by itself. It takes 20 watts just to power a dim light bulb; however, in the field of microelectronics this is a development with many potential applications. At the chip-level it could be used to fuel biomedical devices such as a small portable ovulation predictor operating at sub-microwatt outputs. The conductivity of a woman’s saliva changes up to five days before her ovulation period. The device would measure the conductivity and extract power from the saliva to send a reading to her cellphone and alert her.

Other research at Penn State University is currently studying the application of MFC’s to produce electricity while simultaneously treating wastewater, essentially addressing two environmental issues at once. MFC’s reflect a giant leap in the sphere of renewable energy. If organic matter harvested from saliva can produce electricity, it opens doors to energy extraction from virtually any material containing organic substances, even biodegradable waste.

For more information on MFC’s run on saliva and wastewater treatment, visit Penn State’s press release and research page