16 August 2005

Shocking Results From Urine Tests

by Kate Melville

For researchers pioneering new diagnostic methods, the race is on to design ever smaller biochips that can test for a variety of diseases at once, give instant results, and most importantly, be mass produced cheaply. One of the stumbling blocks up until now has been finding an electrical power source as small and cheap to fabricate as the detection technology itself.

But now, debunking the notion that Scottish researchers would be the first to produce a wee battery, physicists in Singapore have succeeded in creating the first paper battery that generates electricity from urine. They believe the new battery will be the ideal power source for cheap, disposable testing kits for diseases such as diabetes. The researchers, led by Dr Ki Bang Lee, have had their work published in the Institute of Physics' Journal of Micromechanics and Microengineering.

The researchers, from Singapore's Institute of Bioengineering and Nanotechnology, said that the new battery is small and cheap to fabricate. "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," said Lee.

Urine is widely used for testing for tell-tale signs of various diseases and also as an indicator of a person's general state of health. Lee envisions 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.

The battery unit itself 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 laminated, which involves passing the battery unit between a pair of transparent plastic films through a heating roller at 120�C. The final product has dimensions a little smaller than a credit card. Using 0.2 ml of urine, the battery generated a voltage of around 1.5 V with a corresponding maximum power of 1.5 mW. They also found that voltage, power and duration may be designed or adjusted by changing the geometry or materials used.

Lee says that people will easily be able to test themselves at home, seeking medical attention only when necessary. "These fully-integrated biochip systems have a huge market potential," he concluded.

Source: Media release - Institute of Physics