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Porous silicon-based optical microsensors for volatile organic analytes: effect of surface chemistry on stability and specificity.

Authors
Ruminski-AM; King-BH; Salonen-J; Snyder-JL; Sailor-MJ
Source
Adv Funct Mater 2010 Sep; 20(17):2874-2883
NIOSHTIC No.
20037168
Abstract
Sensing of the volatile organic compounds (VOCs) isopropyl alcohol (IPA) and heptane in air using sub-millimeter porous silicon-based sensor elements is demonstrated in the concentration range 50-800 ppm. The sensor elements are prepared as one-dimensional photonic crystals (rugate filters) by programmed electrochemical etch of p++ silicon, and analyte sensing is achieved by measurement of the wavelength shift of the photonic resonance. The sensors are studied as a function of surface chemistry: ozone oxidation, thermal oxidation, hydrosilylation (1-dodecene), electrochemical methylation, reaction with dicholorodimethylsilane and thermal carbonization with acetylene. The thermally oxidized and the dichlorodimethylsilane-modified materials show the greatest stability under atmospheric conditions. Optical microsensors are prepared by attachment of the porous Si layer to the distal end of optical fibers. The acetylated porous Si microsensor displays a greater response to heptane than to IPA, whereas the other chemical modifications display a greater response to IPA than to heptane. The thermal oxide sensor displays a strong response to water vapor, while the acetylated material shows a relatively weak response. The results suggest that a combination of optical fiber sensors with different surface chemistries can be used to classify VOC analytes. Application of the miniature sensors to the detection of VOC breakthrough in a full-scale activated carbon respirator cartridge simulator is demonstrated.
Keywords
Analytical-processes; Analytical-instruments; Analytical-chemistry; Sampling-equipment; Samplers; Volatiles; Organic-compounds; Organic-chemicals; Author Keywords: porous silicon; photonic crystals; remote sensors; chemical sensors; volatile organic compounds
Contact
Michael J. Sailor, Department of Chemistry and Biochemistry, The University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0358 (USA)
CODEN
AFMDC6
Publication Date
20100909
Document Type
Journal Article
Email Address
msailor@ucsd.edu
Fiscal Year
2010
NTIS Accession No.
NTIS Price
Issue of Publication
17
ISSN
1616-301X
NIOSH Division
NPPTL
Source Name
Advanced Functional Materials
State
PA; CA
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