Power of Pee Runs a Battery

Scientists have developed a way to turn pee into electricity. And there's plenty where that came from, they point out.

Cheap, disposable, and renewable, urine-powered batteries may be the perfect power source for disposable healthcare test kits called biochips, the researchers say.

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

The research is detailed in the Aug. 15 issue of the Institute of Physics' Journal of Micromechanics and Microengineering.

Scientists around the world are clamoring to design inexpensive biochips to quickly test for a variety of diseases. But no one has been able to make a similarly small and inexpensive power source.

Lee and his team of researchers at Singapore's Institute of Bioengineering and Nanotechnology have tackled this problem by using the very substance being tested - urine - to power the test.

To make the battery, Lee and his team soaked a piece of paper in copper chloride and then sandwiched it between strips of magnesium and copper. Then they laminated the credit card-sized unit between transparent plastic films.

When a drop of urine is added to the copper chloride paper, a chemical reaction takes place and produces electricity, which is harnessed by the battery. A few drops will generate about 1.5 volts, the same as a AA battery. The battery needs to be developed further to make it commercially viable.

"Our urine-activated battery would be integrated into biochip systems for healthcare diagnostic applications," Lee said.

Lee and his team also found that they could alter the battery's performance - voltage, power, or duration - by adjusting the design or materials.

The chemical composition of urine indicates a person's general health and is widely used in diagnostic tests. For instance, doctors measure the concentration of the sugar glucose to determine whether someone is diabetic.

Lee predicts that one day people will be able to monitor their own health at home using biochips powered by this type of battery.

"These fully-integrated biochip systems have a huge market potential," Lee said.

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