Monitoring pollution in living colour

A normal PC and webcam are being used to monitor the build-up of environmentally important gases such as carbon monoxide and NOx, in a research project under way at

division of applied physics in

.

The technique, which is being developed by a team of Swedish and Italian scientists led by Anders Lundström, could also provide medical diagnoses in remote areas.

'Computer and web cameras are generally available and we would like to provide analytical capabilities to this platform,' Lundström said. 'The real demonstration of its potential came with our recent work using porphyrins to detect environmentally interesting pollutants.'

Lundström's team have been working on a way to use a webcam to transmit colorimetry information — the measure of colour, hue, purity and brightness — from test strips using porphyrins. These are a class of organic compounds, many of which include metal atoms, such as haemoglobin, which tend to be highly coloured, and can change colour when they bind to gas molecules.

The scientists mixed three different porphyrin pigments in a polymer and put drops on a glass slide attached to a computer monitor. This was set to display 50 different colours — each made up of different intensities of red, green and blue light — and a webcam recorded the absorption and fluorescent intensities of the three colours on the slide.

When gases such as CO or NOx are absorbed by porphyrins, the recorded colour measurements provide 'fingerprints' that can identify and quantify the different gases.

'The idea in the long run is to couple this to something like Google Earth,' Lundström said. 'We would then be able to get maps of environmental parameters, coupled to the geographical position of the computer-webcam platform.'

The dyes used in this technique could be any indicator that changes colour in the presence of an analyte — for example, diagnostic test strips commonly used for urine and blood samples.

'This could provide primary healthcare with simple colorimetry medical diagnosis,' Lundström said. 'This is now being done with solitary instruments, but in a year or two could be done with a computer-web camera combination [via the internet] instead. And once we have a secure enough analytical platform, it could even be used for home diagnosis.'