Scientists in Singapore have invented a battery powered by urine.

"We are striving to develop cheap, disposable, credit card-sized biochips for disease detection. Our battery can easily be integrated into such devices, supplying electricity upon contact with biofluids such as urine," says Ki Bang Lee, PhD, MS, in a news release.

Lee is a principal research scientist at the Institute of Bioengineering and Nanotechnology, where the battery was developed. The battery is described in the Journal of Micromechanics and Microengineering.

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How It Works

The battery sandwiches copper, paper laced with copper chloride, and magnesium between two plastic layers. The "sandwich" is later laminated.

"When a droplet of human urine is added into the battery... the urine soaks through the paper between the magnesium and copper layers. The chemicals dissolve and react to produce the electricity," write Lee and colleagues.

In tests, the battery produced a maximum of 1.47 volts, dropping a bit with time but keeping a constant voltage of 1.04 volts for 90 minutes, write the scientists. The battery could be used in home-based health kits, they suggest.

Part of their paper describing the battery was presented in Kyoto, Japan, at the 4th International Workshop on Micro and Nanotechnology for Power Generation and Energy Conversion Applications.

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By Miranda Hitti, reviewed by Brunilda Nazario, MD

SOURCES: Lee, K. Journal of Micromechanics and Microengineering, September 2005; vol 15: pp S210-S214. News release, Institute of Bioengineering and Nanotechnology. News release, Institute of Physics.