August 16, 2005
Urine-powered battery for cell phones
The first urine-powered paper battery has been created in Singapore, reports New Scientist. The credit-card sized unit could be a useful power source for cheap healthcare test kits for diseases like diabetes, and could even be used in emergency situations to power a cellphone.
To activate the battery, a drop of urine is added and soaks through the sandwiched filter paper. The chemicals dissolve and react to produce electricity. The magnesium layer acts as the anode, losing its electrons. And the copper chloride acts as the cathode, mopping up the electrons.
The urine-powered battery was able to generate a voltage of about 1.5 volts – with a corresponding power of 1.5 micro-watts – using just 0.2 millilitres of urine, says Ki Bang Lee, at the Institute of Bioengineering and Nanotechnology in Singapore. And if a second droplet of urine was added 15 hours after the battery was first activated, the replenished urine could generate still more electricity.
The battery is currently suited for use with disposable devices – it is not yet ready to power laptops or iPods. "But if, for example, we place a small cellular phone or transmitter on a plastic card, the chip will work as a disposable biofluid-activated means of communication in an emergency," Lee added.
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