Urine contains many ions (electrically charged atoms), which allows the electricity-producing chemical reaction to take place in the urine battery, said UC Berkeley's Kammen. Other bodily fluids, such as tears, blood, and semen, would work easily as well to activate the battery.
"Little bags of urine may generate chuckles," Kammen said. "But really urine is just a nice example [of] a whole variety of compounds that do this stuff." Even children's lunch-box fruit-juice packets are sufficient, he added.
While medical devices inspired the urine battery, it can activate any electric device with low power consumption, according to Lee, the battery's co-inventor.
"For example, we can integrate a small cell phone and our battery on a plastic card. This can be activated by body fluids, such as saliva, during an emergency," he said.
According to Kammen the technology could even be applied to laptop computers, mp3 players, televisions, and cars. Body-fluid-powered batteries "can do all kinds of things. The issue is how they scale up" to produce more power, he said.
One approach is to simply build larger batteries. Another method is to link lots of little battery cells side by side, which is how the batteries in laptop computers work, Kammen explained.
Kammen, who advocates government funding for alternative energy research, says the wide number of applications for cheap and efficient biofluid-powered batteries illustrates the value of research. "Investigation leads to innovation," he said.
Free E-Mail News Updates
Sign up for our Inside National Geographic newsletter. Every two weeks we'll send you our top stories and pictures (see sample).
SOURCES AND RELATED WEB SITES