Australasian Science: Australia's authority on science since 1938

A Quantum Leap in Nanosensor Efficiency

New research has revealed how to improve nanomaterial efficiency, with potential applications in sensors that can detect minute quantities of chemicals in air and water.

In a study published in Nature Communications, University of Melbourne researchers found that pairs of closely spaced gold nanoparticles can act as optical antennas that concentrate the light shining on them into tiny gaps between the nanoparticles. The light levels in these gaps can now be detected by laser spectroscopy.

The team found the precise geometry of nanoparticle pairs that maximises the concentration of light in this gap. This geometry determines the efficiency of a potential sensor.

“Up until now there were two competing theories surrounding what gap was required between particles to best concentrate the light, but we now have the technology to test it,” said Prof Ken Crozier.

Lead author Dr Wenqi Zhu, who performed the work under Crozier’s supervision as a PhD student at Harvard University, said: “We found that as the gap width decreased, the signal increased until the gap width reached the atomic scale, after which the signal began to decrease – giving us the gap width that optimises the signal from the molecules.”