Taking a pee could recharge your batteries

Recharging your batteries could take on a whole new meaning if a new breakthrough in micro-engineering gains commercial acceptance.

Physicists in Singapore have succeeded in creating the first paper battery that generates electricity from urine.

Researchers say the new device would be perfect for cheap, disposable healthcare test-kits for diseases such as diabetes. The battery is small, cheap to make and which ingeniously uses the bio-fluid being tested as the power source for the device doing the testing.

Dr Ki Bang Lee, who led the research for Singapore’s Institute of Bioengineering and Nanotechnology, said: “We are striving to develop cheap, disposable credit card sized biochips for disease detection. Our battery can be easily integrated into such devices, supplying electricity upon contact with biofluids such as urine.”

The battery unit is made from a layer of paper that is steeped in copper chloride and sandwiched between strips of magnesium and copper. This “sandwich” is then held in place by being laminated.

The final product has dimensions of 60mm by 30mm and a thickness of just 1mm – a little smaller than a credit card. Just a drop of urine, 0.2ml, can generate 1.5 V with a corresponding maximum power of 1.5mW.

Researchers found that the battery performance may be designed or adjusted by changing the geometry or materials used. Writing in the Institute of Physics Journal of Micromechanics and Microengineering, Lee says that fully-integrated biochip systems have a huge market potential.

Although they are currently only suited for disposable devices, Lee says if a small cellular phone or transmitter were placed on a plastic card, the chip could act as a disposable bio-fluid activated communication tool in an emergency.

However, for now, Lee sees the batteries being integrated into biochip systems for healthcare diagnostic applications and he envisions a world where people will easily be able to monitor their health at home, seeking medical attention only when necessary.

David Hopkins

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