Single- and Multi-Transducer Arrays Employing Nanoparticle Interface Layers as Vapor Detectors for a Microfabricated Gas Chromatograph.

[摘要] This body of research focuses on improving microsensor arrays used as detectors in Si-microfabricated gas chromatographs (µGC) for the determination of volatile organic compounds (VOCs).By means of such improvements, µGC technology should find wider application in homeland security, disease diagnosis, and environmental monitoring.The microsensors considered here all employ thiolate-monolayer-protected gold nanoparticles (MPN) as vapor sorptive interface layers.The central hypothesis is that by altering the MPN ligand, core size, and/or the underlying transducer, the diversity of responses to VOCs provided by microsensor arrays with MPN interfaces can be improved.The first study evaluated a single transducer (ST) array of MPN-coated chemiresistors (CR) as a µGC detector for three semi-volatile markers of the explosive 2,4,6-trinitrotoluene in the presence of alkane interferences of similar volatility.The effects of flow rate and temperature on chromatographic resolution, sensitivity, and limits of detection (LOD) were assessed.Under optimized conditions, a complete analysis required < 2 minutes, targets were separated from interferences, unique response patterns were obtained, and LODs were ≤ 4 ng.In the second study, data from four MPN-coated CRs and four similarly coated thickness shear mode resonators (TSMR) were combined to compare ST and multi-transducer (MT) arrays with respect to response diversity for a set of five VOCs and their binary mixtures.Extended disjoint principal regression (EDPCR) analysis was coupled with Monte Carlo simulations to assess the performance of all possible combinations of CRs and TSMRs in terms of the recognition rate (RR).The best 4-MT arrays generally outperformed the best 4-ST arrays, but array composition was critical.In the third study, the plasmonic behavior of the MPN films was exploited by assessing the changes in the absorbance spectrum at three probing wavelengths.A set of seven MPN films of different ligand functionalities and Au core diameters between 4 and 40 nm was exposed to 6 individual vapors.Vapor discrimination was achieved both with single MPN films and arrays of just 2 films (RR > 95%).These types of sensor arrays can enhance the vapor discrimination of sorption-based detectors utilized in µGC technology, making the analysis of complex VOC mixtures possible.

[发布机构] University of Michigan

[效力级别] Chemistry

[关键词] Nanoparticle-coated microsensor arrays used as detectors in microfabricated gas chromatographs;Chemistry;Science;Chemistry