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Glucose molecules 'dancing' on sensor surface illuminated by light

Biochip that uses plasmonic interferometers

Engineers at Brown University have designed a biochip that uses plasmonic interferometers and can measure glucose concentrations in human saliva. In this graphic, each plasmonic interferometer -- thousands of them per-square-millimeter -- consists of a slit flanked by two grooves etched in a silver metal film. The schematic shows glucose molecules "dancing" on the sensor surface illuminated by light with different colors. Changes in light intensity transmitted through the slit of each plasmonic interferometer yield information about the concentration of glucose molecules in solution.

The technique takes advantage of a convergence of nanotechnology and surface plasmonics, which explores the interaction of electrons and photons (light). The engineers etched thousands of plasmonic interferometers onto a fingernail-sized biochip and measured the concentration of glucose molecules in water on the chip. Their results showed that the specially designed biochip could detect glucose levels similar to the levels found in human saliva. Glucose in human saliva is typically about 100 times less concentrated than in blood. The biochip could be used to measure a range of biological and environmental substances, and could eliminate the need for diabetics to draw blood to check their glucose levels.

The research was supported in part by the National Science Foundation (NSF). The fabrication work was performed at the Brown Microelectronics Facility, a member of the Materials Research Facilities Network, which is supported by NSF (grant DMR 05-20651), and at the IMNI/Electron Microscope Facility (the focused ion beam used to fabricate the plasmonic sensors was acquired through NSF grant DMR 08-21008).

To learn more, see the Brown news story Biochip measures glucose in saliva, not blood. (Date of Image: September 2011)

Credit: Domenico Pacifici, School of Engineering, Brown University
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