Researchers developed a new sensor that can detect and count nanoparticles as small as 10 nanometers, in the future it could detect even smaller particles, viruses, and molecules.
Nanoparticles are all around us and can benefit human health as early cancer treatments or interfere with it in viruses and pollution, Washington University in St. Louis reported.
The Raman microlaser sensor in a silicon dioxide chip has the ability to find nanoparticles without needing to "dope" the chip with rare-earth ions providing optical gain for the microlaser; this cuts costs and biocompatibility risks.
"This gives us the advantage of using the same dopant-free sensor at different sensing environments by tailoring the lasing frequency for the specific environment, for example, at the band where the environment has minimum absorption, and for the properties of the targeted nanoparticles by just changing the wavelength of the pump laser," said Sahin Kaya Ozdemir, PhD, a research scientist in the research team and the first author of the paper.
The team integrated the Raman lasing in a silica microcavity with the mode splitting technique to develop the more powerful sensor.
The technology could benefit the "electronics, acoustics, biomedical, plasmonics, security and metamaterials fields."
"Our new sensor differs from the earlier whispering gallery sensors in that it relies on Raman gain, which is inherent in silica, thereby eliminating the need for doping the microcavity with gain media, such as rare-earth ions or optical dyes, to boost detection capability," Ozdemir said. "This new sensor retains the biocompatibility of silica and could find widespread use for sensing in biological media."
"It doesn't matter what kind of wavelength is used, once you have the Raman laser circulating inside and there is a molecule sitting on the circle, when the beam sees the particle it will scatter in all kinds of directions," study leader Lan Yang said. "Initially you have a counterclockwise mode, then a clockwise mode, and by analyzing the characterization of the two split modes, we confirm the detection of nanoparticles."
The research appears in the Proceedings of the National Academy of Sciences online Early Edition Sept. 1, 2014.
