Microlasers that are able to detect minuscule individual nanoparticles may be able to be used to detect viruses.
Researchers from Washington University, St Louis, created the system, which is able to detect and individually count nanoparticles at sizes of 10 nanometers.
Nanoparticles can be between 1 and 100 nanometers in size – with a nanometer being the equivalent to one billionth of a meter.
They are now aiming to develop the technology to be able to detect particles that are smaller than nanoparticles, which includes viruses.
The technology will benefit a number of fields including electronics, acoustics and biomedical applications.
The team that worked on the microlasers created a Raman sensor in a silicon dioxide chip to find the individual particles.
Previously, to identify the nanoparticles they would have had have to include rare ions in the chip to provide optical gain for the laser.
Researcher Sahin Kaya Ozdemir, who worked on the project, said that when generating the Raman laser beam in the resonator it will split into two to and provide a reference for the other beam to sense the particle.
“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.
“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.”
“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 work, which was led by Lan Yang from the university, works in a similar way to that of the whispering gallery in London’s St Paul’s Cathedral.
In this space, which is the inside of the building’s iconic dome, one person can hear a message that is spoken to the wall by another person on the other side.
Unidirectional microlasers were first demonstrated in 2010 by scientists at Harvard University.
Featured image courtesy of Jeff Keyzer. Inline image one courtesy of J. Zhu, B. Peng, S.K. Ozdemir and L. Yang, image two courtesy of Harvard School of Engineering and Applied Sciences.