An engineer at Purdue University in Indiana has designed a new kind of medical patch that is powered by yeast farts.

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The patch is designed to transfer drugs into the body by reacting with body heat. The power of the patch comes from carbon dioxide produced by ordinary baker's yeast. During tests, researchers inject water into the pump before placing the pump on someone's skin. The body heat was found to be sufficient in activating the yeast.

Using this method, the patch will be able to efficiently deliver medicine without the need of a power source. More details from Discovery:
The carbon dioxide eventually inflates the yeast-and-sugar chamber of the pump bubble, putting pressure on the other chamber to pump out some of its drug. Ziaie and a doctoral student studying with him, Manuel Ochoa, built a half-inch (15 millimeters) prototype that pumps continually for more than two hours, they reported in August in the journal Lab on a Chip. Ziaie envisioned people just throwing away the patch after the reaction was over.

A yeast-powered pump may be less bulky than battery-powered pumps other researchers have made, Ziaie said. Yeast fungi also are able to live for a long time in a dried state, so patches using a yeast pump should last a long time.