Nano-nose for asthma watch

Scientists are developing a wristwatch that will tell asthma sufferers when they are at risk of having an attack.

The watch would act as a type of mechanical nose, monitoring the levels of certain gasses which are known to irritate the airways such as ozone, unburnt hydrocarbons from petrol and the oxides of nitrogen.

It would give wearers a warning that would allow them to take preventative steps such as retreating indoors or making sure they had an inhaler to hand.

Researchers from Birmingham University, UK, plan to engineer the sensor using nanotechnology - an emerging form of engineering where the scale of things is measured in just a few millionths of a millimetre.

Small space

This should allow for many more functions to be shrunk into as small a space as possible.

"The idea of a nano-nose is that it would be microscopic in size and be sensitive to six gases in parallel," Professor Richard Palmer told the British Association's Festival of Science.

"You would be walking down the road and your wristwatch display could show you the spectrum of gases in the atmosphere - gases that you wouldn't know were there until you got your asthma attack."

The research has supporting funds from British Nuclear Fuels Limited.

Computer chip

The tiny sensor would work by measuring the electric current flowing through gas molecules trapped in a chip.

"A voltage is applied across the chip and then the gas flows in and changes the current. And as you scan the voltage, you get a spectrum that discloses the gases that are present."

Professor Palmer expects to have a working demonstrator within five years. And although some nanotechnology is hugely expensive, he believes the watches will be affordable.

"I think we can fabricate this sensor by an extension of the methods of modern mass production of computer chips," he said.