While there's no denying that implantable medical devices such as pacemakers save peoples' lives, powering those implants is still a tricky business. The batteries in a standard pacemaker, for instance, are said to last for about eight years - after that, surgery is required to access the device. Implants such as heart pumps are often powered by batteries that can be recharged from outside the body, but these require a power cord that protrudes through the patient's skin, and that keeps them from being able to swim or bathe. Now, however, scientists at Germany's University of Freiburg are developing biological fuel cells, that could draw power for implants from the patient's own blood sugar.

The research team is being led by Dr. Sven Kerzenmacher, of Freiburg's Department of Microsystems Engineering. They are looking into the use noble metal catalysts, such as platinum, to trigger a continuous electrochemical reaction between glucose in the blood and oxygen from the surrounding tissue fluid. The use of platinum (or a similar metal) would be ideal, as the material exhibits long-term stability, it can be sterilized, and electrodes made from it wouldn't be sensitive to unwanted chemical reactions, including hydrolysis and oxidation.

The Freiburg scientists are ultimately hoping that the surfaces of implants could be covered with a thin coating of the fuel cells, which would then power the devices indefinitely.