Sensor sniffs out toxic gases

A postage-stamp-sized sensor that can detect poisonous gases and toxins by changing colour is being developed by the National Institute of Environmental Health Sciences (NIEHS).

The wearable sensor is part of a Genes, Environment and Health Initiative (GEI) and once launched is expected to be used in applications that pose a chemical health risk in the workplace or through accidental exposure.

NIEHS director Linda Birnbaum, said: ‘The project fits into the overall goal of a component of the GEI Exposure Biology Program that the NIEHS has the lead on, which is to develop technologies to monitor and better understand how environmental exposures affect disease risk.’

The NIEHS’s work has been published in a paper by senior author Kenneth Suslick, and MT Schmidt Professor of Chemistry at Illinois University at Urbana-Champaign. In the paper they describe the device as an ‘optoelectronic nose’ for the detection of toxic industrial chemicals (TICs).

The device will work as a chemical equivalent to the radiation badges worn in some work places. Researchers claim that existing methods are based on sensors that respond to weak and non-specific chemical reactions while the new technology is able to respond to a larger range of chemicals.

‘We have a disposable 36-dye sensor array that changes colours when exposed to different chemicals. The pattern of the colour change is a unique molecular fingerprint for any toxic gas and also tells us its concentration,’ explained Suslick. ‘By comparing that pattern to a library of colour fingerprints, we can identify and quantify the TICs in a matter of seconds.’

So far the device has undergone trials involving 19 examples of toxic industrial chemicals including ammonia, chlorine, nitric acid and sulphur dioxide at concentrations known to be immediately dangerous to health. The arrays were exposed to the chemicals for two minutes. Most of the chemicals were identified from the array colour change in a number of seconds and almost 90 per cent of them were detected within two minutes.

‘One of the nice things about this technology is that it uses components that are readily available and relatively inexpensive,’ said David Balshaw, a programme administrator at the NIEHS. ‘Given the broad range of chemicals that can be detected and the high sensitivity of the array to those compounds, it appears that this device will be particularly useful in occupational settings.’

The team currently has a working prototype and plans to market the sensor within the next few years.