Ultra-sensitive sulphur detector

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A US researcher has received a grant to develop a sensor that will detect sulphur impurities in petrol and diesel down to the parts per billion levels.

A Kaan Kalkan, the assistant professor of mechanical and aerospace engineering at Oklahoma State University, received the two-year $89,480 (£59,578) grant from the Oklahoma Center for the Advancement of Science and Technology.

The US, Europe, Canada and Japan have regulated the sulphur level in diesel and gasoline from 500 to 15 parts per million. Such stringent regulation imposes obligations to monitor sulphur content at all points from manufacture through to distribution.

The active element of Kalkan’s sensor is a layer of silver nanoparticles. Kalkan employs a novel nanofabrication technique developed in his lab to synthesize the nanoparticles on a semiconductor thin film. The particles are separated by only a few nanometres, leading to strong electromagnetic interaction between them.

As a result, the particles exhibit a strong and well-resolved hybrid plasmon resonance. This resonance, which can easily be monitored by a hand-held spectrophotometer, is very sensitive to sulphur residues. As the sulphur residues attach to the nanoparticles, the resonance is significantly damped, even at part per billion levels.

Kalkan has already developed a prototype of the sensing device and will now work to commercialise it in a joint effort with Ametek Oil and Gas.

The presence of sulphur in fuels has several adverse effects, including corrosion in engines and acid rains, quick deterioration of expensive catalytic converters in vehicles resulting in air pollution, inefficient combustion in engines and particulate formation that also leads to yet more air pollution.