Ring of Laser Light Can Count Individual Viruses and Nanoparticles

Wednesday, June 29, 2011 - 11:01 in Physics & Chemistry

Counting Nanoparticles with Lasers J. ZHU, L. HE, S. K. OZDEMIR, AND L. YANG/WUSTL Researchers at Washington University in St. Louis have turned an acoustic phenomenon familiar to those who have visited the Statuary Hall in the U.S. Capitol Building or St. Paul's Cathedral in London into a high-resolution nanoparticle detector. Using a ring-shaped micro-laser, the sensor can detect and count individual viruses or synthetic and biological nanoparticles with single particle resolution. The sensor is what's known as a "whispering gallery resonator" and relies on the same principles as those acoustic spaces (like the aforementioned Capitol and cathedral galleries) where whispers on one side of the room can be heard directly on the other side thanks to the unique properties of the shape of the space. But unlike the acoustic spaces (which are usually in round, domed spaces) that have audible sweet spots, the new sensor has optical sweet spots. There's a...

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