Researchers at Chalmers University of Technology have built a simple nanoantenna that directs red and blue colors in opposite directions, even though the antenna is smaller than the wavelength of light. The findings – published in the online journal Nature Communications this week – can lead to optical nanosensors being able to detect very low concentrations of gases or biomolecules.

The Chalmers researchers built an antenna with an asymmetric material composition, creating optical phase shifts. The antenna consists of two nanoparticles about 20 nanometers apart on a glass surface, one of silver and one of gold. Experiments show that the antenna scatters visible light so that red and blue colors are directed in opposite directions.

The Chalmers team controlled the light by using asymmetric material composition, such as silver and gold. The researchers have shown that the antennas can be fabricated densely over large areas using cheap colloidal lithography.

Nanoplasmonics can be applied in a variety of areas, says Mikael Käll, professor in the research group at Chalmers.

“One example is optical sensors, where you can use plasmons to build sensors which are so sensitive that they can detect much lower concentrations of toxins or signaling substances than is possible today. This may involve the detection of single molecules in a sample, for example, to diagnose diseases at an early stage, which facilitates quick initiation of treatment.”

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Also: Learn about the development of soldier-conformable antennas  using conducting polymers.


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