Scientists create urine-powered battery
that generates electricity from urine. This new battery could solve
the problem of finding a power source as small and as cheap to
fabricate as the disposable healthcare test-kit applications for
diseases such as diabetes.
The emergence of biochips that can test for a variety of diseases at once giving instant results has led to the creation of additional problems. Cost is crucial, with the ability to mass produce the chips on an industrial scale a determining factor in its success.
More importantly, a cheap and reliable power source that could be integrated with bioMEMS devices such as home-based health test kits providing a power source for the electronic circuit, has been an ongoing problem until now.
Led by Dr Ki Bang Lee, a research team at Singapore's Institute of Bioengineering and Nanotechnology (IBN) have developed a paper battery that is small, cheap to fabricate, and uses the fluid being tested (urine) as the power source for the device doing the testing.
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 (a little bit smaller than a credit card).
Lee described in his study how the battery was created and quantifies its performance. Using 0.2 ml of urine, they generated a voltage of around 1.5 V with a corresponding maximum power of 1.5 mW.
The team said that battery performances (such as voltage, power or duration) could be designed or adjusted by changing the geometry or materials used.
Dr. Lee 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 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.
The concentration of glucose in urine is a useful diagnostic tool for diabetics. The lead researcher, Dr 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.
For example, glucose concentration in blood can be used as a marker for the diagnosis of diabetes and it could be detected by means of glucose oxidase (GOD). Over the past few decades, researchers have developed several means of monitoring the urine glucose concentration, multianalyte sensors for the detection of hypoxanthine, xanthine and uric acid and an enzyme sensor for urea detection.
"Our urine-activated battery would be integrated into biochip systems for healthcare diagnostic applications," said Lee. He envisioned a world where people will easily be able to monitor their health at home, seeking medical attention only when necessary.
"These fully-integrated biochip systems have a huge market potential," added Lee.
This research is published in the Aug 15th edition of the Institute of Physics' Journal of Micromechanics and Microengineering.
