Although it's generally not a good idea to swallow batteries, ingestible medical electronic devices often have batteries in them. A new type of battery could make such devices safer to use, as it's made entirely of edible ingredients.

The experimental edible battery was developed at the Istituto Italiano di Tecnologia (IIT-Italian Institute of Technology) by a team led by senior researcher Mario Caironi. It was inspired by the biochemical redox reactions which produce energy in the cells of humans and all other animals.

The battery's anode is composed of riboflavin (aka vitamin B2), while its cathode is made of quercetin. Both substances are found naturally in a variety of plants and other foods. Activated charcoal is additionally used to increase conductivity.

The electrolyte is water-based, and the separator (a permeable membrane between the anode and cathode, that prevents short circuits) is made of nori seaweed, which is commonly used in sushi. Finally, two food-grade gold foil contacts protrude out from a beeswax coating on the anode and cathode.

Once it's been charged, the 0.65-volt battery is capable of providing a 48-microampere current for 12 minutes or just a few microamps for over one hour. While that might not sound like much, it's reportedly sufficient to power small electronic devices such as low-power LEDs.

"Future potential uses range from edible circuits and sensors that can monitor health conditions to the powering of sensors for monitoring food storage conditions," said Caironi. "Moreover, given the level of safety of these batteries, they could be used in children toys, where there is a high risk of ingestion. Actually, we are already developing devices with greater capacity and reducing the overall size."

The research is described in a paper that was recently published in the journal Advanced Materials. Scientists at Carnegie Mellon University previously developed an edible battery of their own, which utilizes the melanin pigments which occur naturally in people's skin, hair and eyes.