Washington, Sep 2 (IANS): In a major breakthrough, a team of researchers has developed a new sensor that can detect and count nano-particles, at sizes as small as ten nano-metres, one at a time.

Engineered materials about a billionth of a metre in size, nanoparticles can benefit human health, as in some innovative early cancer treatments, but they can also interfere with it through viruses, air pollution, traffic emissions, cosmetics, sunscreen and electronics.

The sensor could potentially detect much smaller particles, viruses and small molecules, the researchers said.

They created the Raman micro-laser sensor in a silicon dioxide chip to find individual nano-particles without the need to "dope" the chip with chemicals called rare earth ions to provide optical gain for the micro-laser.

"Our new sensor differs from the earlier whispering gallery sensors in that it relies on Raman gain, which is inherent in silica," said Sahin Kaya Ozdemir, a research scientist at Washington University in St. Louis.

Raman gain is optical gain (amplification) arising from stimulated Raman scattering.

The study appeared in the journal Proceedings of the National Academy of Sciences.