AVS 50th International Symposium
    Homeland Security Topical Conference Wednesday Sessions
       Session HS-WeP

Paper HS-WeP6
A Portable GC with a Nanosensor Array Detector

Wednesday, November 5, 2003, 11:00 am, Room Hall A-C

Session: Poster Session on Science & Technology for Homeland Security
Presenter: A.W. Snow, Naval Research Laboratory
Authors: A.W. Snow, Naval Research Laboratory
H. Wohltjen, Microsensor Systems, Inc.
N.L. Jarvis, U.S. Army Edgewood Chemical and Biological Center
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Development of portable rapid-screening analytical methods/instrumentation for the detection of chemicals identified by the Chemical Weapons Convention (CWC) as associated with the production and use of agents is an activity of interest to homeland security as well as to CWC inspection capabilities. The instrument described in this presentation consists of a temperature programmable gas chromatograph combined with a novel detector array based on gold nanocluster chemresistors.@footnote 1,2@ In this configuration peaks eluting from the GC are "fingerprinted" by the detector array using an on-board pattern recognition computer and an on-board library look-up. The thermoelectrically cooled array detector is very compact, works with any carrier gas, and uses minimal power. The array detector consists of four interdigital microelectrodes coated with different gold nanocluster materials. This device structure is called a "MIME" device (a pneumonic for Metal-Insulator-Metal Ensemble which reflects the electron transport through the organic monolayer shells encapsulating the metal cores of adjacent nanoclusters). Absorption of vapors into the insulating ligand shell surrounding the core produces a change in conductivity that is interpreted as a GC detector signal. The vapor sensitivity, selectivity and response time of each MIME device in the array are dependent on the composition, molecular structure and thickness of the ligand shell resulting in the array detector having a unique pattern for a particular analyte or interferent. Numerous candidate materials were evaluated for their effectiveness in the detection of organophosphorus compounds and other chemicals associated with the production of chemical weapons. @FootnoteText@ @footnote 1@ H. Wohltjen and A.W. Snow, "Colloidal Metal-Insulator-Metal Ensemble Chemiresistor Sensor", Anal. Chem. 1998, 70, 2856.@footnote 2@ A.W. Snow, H. Wohltjen, N.L. Jarvis, "MIME Chemical Vapor Microsensors", NRL Review, 2002, 45.