21 February 2002 Artificial nose employing microsphere sensors for detection of volatile organic compounds
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An artificial nose based on microsphere sensor arrays has been developed for the discrimination of numerous volatile organic compounds. Sensor elements consist of 3-5 micron diameter silica and polymer spheres that have a fluorescent, solvatochromic dye adsorbed to the microsphere surface. These sensors respond to changes in the local polarity of the environment by shifting their excitation and/or emission characteristics, thereby indicating the presence of different volatile compounds. High-density microsphere arrays are fabricated which contain thousands of individual sensor elements and multiple copies of each sensor type. By monitoring the sensors temporal fluorescence responses with a CCD camera, unique patterns are recorded that identify individual analytes or are characteristic of a complex mixture. By summing over the redundant sensor elements within an array, the signal-to-noise ratio can be enhanced. These types of sensor arrays have been used to detect and discriminate between different bacterial strains such as Escherichia coli based on characteristic odors from the live and dead bacteria.
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Shannon E. Stitzel, Shannon E. Stitzel, Keith J. Albert, Keith J. Albert, Sergei G. Ignatov, Sergei G. Ignatov, David R. Walt, David R. Walt, "Artificial nose employing microsphere sensors for detection of volatile organic compounds", Proc. SPIE 4575, Chemical and Biological Early Warning Monitoring for Water, Food, and Ground, (21 February 2002); doi: 10.1117/12.456916; https://doi.org/10.1117/12.456916

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