Sensor set to leave the lab

Researchers at Pacific Northwest National Laboratories have shown that an extremely sensitive sensor technology designed for laboratory research could be employed in industrial applications.

Research scientists Nancy Foster-Mills, Tom Autrey and Jim Amonette are experimenting with photoacoustic sensors that provide non-destructive, real-time chemical monitoring of complex mixtures, including those that are difficult to analyse using more conventional techniques.

‘These sensors are 100 to 1,000 times more sensitive than conventional absorption spectroscopy technologies used to identify the presence and concentration of specific chemicals,’ said Foster-Mills, who helped build the Environmental Molecular Sciences Laboratory’s capability in photoacoustic sensors and spectroscopy.

In research funded through the Environmental Management Science Program, scientists used a photoacoustic sensor to determine the concentration of chromate in order to study how minerals in the soil take it up.

‘The technique that we’re using is not only more sensitive, it’s faster,’ said Foster-Mills. ‘It could provide analysis in seconds, where other technologies might take minutes or hours. Because it’s non-destructive, these sensors also are practical for studies of ongoing processes.’

Photoacoustical sensors work through a two step process. The first step is to shine light of the appropriate wavelength on a sample, which excites molecules in a mixture. As the molecules return to a relaxed state, they give off heat. The released heat energy, in turn, creates a pressure wave that travels through the sample. By detecting and measuring the pressure wave, researchers can determine how much of a chemical is in the sample.

Photoacoustic sensor technologies could potentially be used for routine analysis in industry most anywhere that nondestructive, in situ, real-time monitoring is needed and could be integrated into continuous monitoring devices.

‘With their better detection limits, photoacoustic sensors could be valuable in quality assurance, industrial processing, safety, and environmental monitoring,’ said Foster-Mills.

Researchers are working to make the technology less expensive and more portable. One approach is to use alternative light sources and eliminate the need for lasers, which can be costly and bulky.

Pacific Northwest is seeking industrial partners, including those who may be interested in co-operative Research and Development Agreements, to help develop photoacoustic sensor technology to meet their needs.