Scientists at the Okinawa Institute of Science and Technology Graduate University (OIST) have developed a light-based device that can act as a biosensor, detecting biological substances in materials; for example, harmful pathogens in food samples.
Current industry-standard biosensors have limited sensitivity and precision. They can only detect cumulative effects of groups of particles, rather than individual molecules. But the tool the team developed is 280 times more sensitive.
In collaboration with researchers from the University of Wisconsin, USA, researchers in OIST’S Light-Matter Interactions for Quantum Technologies Unit used this tool, a type of optical resonator, to create high-resolution, real-time images of individual nanoparticles.
Their findings are published in ACS Nano (“Toward Real-Time Monitoring and Control of Single Nanoparticle Properties with a Microbubble Resonator Spectrometer”).
For the last several years, the OIST scientists have been experimenting with microbubble resonators, a type of microresonator that consists of a hollow glass shell attached to a long, thin glass capillary. The researchers fill a microbubble resonator with water. Then, when they shine beams of light onto it, light waves circulate quickly through the water, allowing scientists to do study physical and chemical properties of particles on the resonator’s surface.
For the present study, the collaborating researchers from the University of Wisconsin coated the inside of the microbubble resonator’s glass sphere with gold nanorods.
The scientists shined a laser beam to heat the nanorods, then observed how the shape, orientation, and surface chemistry of the nanorods changed when they were exposed to certain chemicals and light fields.

Image Credit:  OIST

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