Electricity from urine

Aug 15 2005

According to physicists in Singapore, they have created the first paper battery that generates electricity from urine.

They maintain that this innovative battery will be the ideal power source for cheap, disposable healthcare test-kits for diseases such as diabetes.

All around the world scientists in research groups are attempting to design even smaller "biochips" that can test for a variety of diseases at once, and give instant results; and of course, be mass produced cheaply.

Until now no one has been able to solve the problem of finding a power source as small and as cheap to produce as the detection technology itself.

However now Dr Ki Bang Lee, and a research team at Singapore’s Institute of Bioengineering and Nanotechnology (IBN) have developed a paper battery that is small, cheap to make, and which ingeniously uses the bio-fluid being tested (e.g. urine) as the power source for the device doing the testing.

The chemical composition of urine is widely used as a way of testing for tell-tale signs of various diseases and also as an indicator of a person’s general state of health, and the concentration of glucose in urine is a useful diagnostic tool for diabetics.

Lead researcher, Dr Lee, has a vision of a world where people will easily be able to monitor their health at home, using disposable test-kits that don’t need lithium batteries or external power sources.

Dr. Lee says they are striving to develop cheap, disposable credit card-sized biochips for disease detection, and their battery can be easily integrated into such devices, supplying electricity upon contact with biofluids such as urine.

Apparently the battery unit is made from a layer of paper that is steeped in copper chloride (CuCl) and sandwiched between strips of magnesium and copper.

This "sandwich" is then held in place by being laminated, which involves passing the battery unit between a pair of transparent plastic films through a heating roller at 120ºC.

The final product has dimensions of 60 mm x 30 mm, and a thickness of just 1 mm, which is slightly smaller than a credit card.

Lee explains that the battery was created and quantifies its performance, and by using 0.2 ml of urine, they were able to generate a voltage of around 1.5 V with a corresponding maximum power of 1.5 mW.

They also found that the battery performances, such as voltage, power or duration, may be designed or adjusted by changing the geometry or materials used.

The research is published in the Journal of Micromechanics and Microengineering.