Discrete Free-Surface Millifluidics for Rapid Capture and Analysis of Airborne Molecules Using Surface-Enhanced Raman Spectroscopy

A lithography-free, low-cost, free-surface millifluidic device is reported using discrete liquid interfaces for capturing and detecting gas-phase analyte molecules at low partial pressures out of a gas flow of time-varying composition. The architecture, based on segmented flow, consists of alternati...

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Bibliographic Details
Published in:Analytical chemistry (Washington) 2014-01, Vol.86 (2), p.1061-1066
Main Authors: Piorek, Brian D, Andreou, Chrysafis, Moskovits, Martin, Meinhart, Carl D
Format: Article
Language:English
Subjects:
Adsorption
Air Pollutants - analysis
Chromatography
Devices
Environmental monitoring
Flocculation
Gas flow
Gases
Humans
Limit of Detection
Liquid phases
Liquids
Metal Nanoparticles - chemistry
Microfluidic Analytical Techniques
Molecules
Nanoparticles
Partial pressure
Raman spectroscopy
Silver
Silver - chemistry
Solutions
Spectrum analysis
Spectrum Analysis, Raman - methods
Sulfanilic Acids - analysis
Surface Properties
Time Factors
Volatilization
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Summary:A lithography-free, low-cost, free-surface millifluidic device is reported using discrete liquid interfaces for capturing and detecting gas-phase analyte molecules at low partial pressures out of a gas flow of time-varying composition. The architecture, based on segmented flow, consists of alternating regions of liquid and gas wherein the liquid regions contain surface-enhanced Raman spectroscopy (SERS)-active silver nanoparticles, while the gas regions contain trace quantities of vapor-phase analyte, thereby controlling and optimizing transport and mixing of the gas-phase analyte with the liquid phase. Once absorbed in the liquid phase, the entrained analyte molecules induce aggregation of the aqueous silver nanoparticles. The resulting aggregates consisting of nanoparticles and adsorbed analyte molecules produce intense SERS spectra that reliably identify the absorbed analyte in real time. The approach can be used to determine the time-variable trace chemical composition of a gas stream with applications in, for example, environmental monitoring and online industrial process monitoring, or as a SERS-based detector following gas chromatographic separation. The operation of the system is demonstrated using 4-aminobenzenethiol vapor at 750 ppb, and the detection response time is
ISSN:0003-2700
1520-6882
DOI:10.1021/ac402628t