Electronic tongue for environmental monitoring

Resource, Jul 2002

United Kingdom researchers are developing a unique electronic tongue that can be dipped into rivers or industrial effluent streams to ensure that the water does not contain any harmful elements.

The researchers, based at Cardiff University's School of Engineering, have demonstrated that the tasting part of the system can be fabricated from very small components, making it potentially easy and inexpensive to mass-produce. The next step would be to link the tongue to a computerized brain to analyze the signals it generates.

The work is being carried out by Professor David Barrow's team, with funding from the Engineering and Physical Sciences Research Council in the United Kingdom.

The system is based on an analytical technique called chromatography, a technique for separating mixtures. Here, the chemical sample, contained in a liquid or a gas, is passed through or over a solid matrix which has a high surface area - for example a glass cylinder packed with silica beads. It is possible to attach a variety of chemical hooks on to the beads, so that as the sample passes down the column of beads different components will be grabbed by the hooks to differing extents. In this way the various components can be separated from the mixture and analyzed.

The Cardiff researchers' system works on broadly similar principles, but on a much smaller scale. If a silicon chip is treated with hydrofluoric acid in a controlled way, it becomes etched with millions of tiny pores and channels.

"It is in effect a tiny chromatographic extraction cartridge," says Barrow.

According to Barrow, the system could be put into a" river or factory process stream to monitor the mixtures flowing through it.

For more information, contact Barrow, barrow@cardiff .ac.uk.