Bacteria-Powered Batteries

... with a little creativity, this idea might make for an interesting energy source for a pacemaker:

In 2008, Lebônê (the word means “light stick” in southern Africa’s Sotho language) field-tested its first prototype in Tanzania, the home country of team member Stephen Lwendo. Simple and cheap, the (microbial fuel cell) MFC came in a 5-gallon bucket. It consisted of a graphite-cloth anode, a chicken-wire cathode, manure-rich mud for fuel, a layer of sand to act as an ion barrier and salt water as an electrolyte—all attached to an electronic power-management board. In June 2009, team members traveled to Namibia to launch a pilot program featuring 100 MFCs made from small canvas bags that can be linked for increased voltage. The bags are filled with dirt and buried. When watered to keep the microbes munching, the buried cells can produce power for months.

... though I'm not sure about the manure-rich mud and sand angles.

-Wes