High Performance Micromachined Planar Field-Asymmetric Ion Mobility Spectrometers for Chemical and Biological Compound D
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High Performance Micromachined Planar Field-Asymmetric Ion Mobility Spectrometers for Chemical and Biological Compound Detection Raanan A. Miller, Angela Zapata1, Erkinjon G. Nazarov2, Evgeny Krylov2, Gary A. Eiceman2 Sionex Corporation, Wellesley Hills, MA 1 Charles Stark Draper Laboratory, Cambridge, MA 2 New Mexico State University, Chemistry and Biochemistry Department, Las Cruces, NM ABSTRACT The micromachined Planar High Field Asymmetric Waveform Ion Mobility Spectrometer (PFAIMS) is a novel detector for chemical and biological sensing applications. This detector fills an unmet market need, providing spectrometer capabilities and extremely high sensitivity, at a cost comparable to stand-alone sensors. The PFAIMS is quantitative, and has detection limits down to the parts-per-trillion. The performance of the PFAIMS in a number of applications ranging from industrial to biomedical, where it is used as both a stand alone sensor, and as a gas chromatographic detector are demonstrated. These applications include the detection of xylene isomers and non-invasive medical diagnosis through breath analysis. INTRODUCTION In this work, a recently developed micro-electro-mechanical (MEMS) spectrometer, based on High Field Asymmetric Waveform Ion Mobility Spectrometry (FAIMS), is presented. This method was originally developed in the Soviet Union in the early 1990’s for chemical warfare applications [1]. The FAIMS method uses the non-linear mobility dependence of ions on high strength RF electric fields for ion filtering, in air at atmospheric pressure [2]. This novel method enables the rapid detection and identification of compounds that can not be resolved by other analytical techniques. The FAIMS method scales down well, allowing miniaturization of the analytical cell using MEMS fabrication, while preserving sensitivity and resolution [3]. The miniature Planar FAIMS spectrometer developed by our group offers a unique combination of high sensitivity (ppb-ppt), new analytical information, simple and rugged construction, small size, mass produciblity, and low cost. This combination of characteristics makes the PFAIMS spectrometer attractive as a quantitative detector that is sufficiently low cost to make it practical to use in a wide range of applications as a chemical sensor. In this paper, we report on the application of this novel MEMS Planar FAIMS to a number of different chemical and biological applications. OPERATION PRINCIPLE PFAIMS spectrometers act as tunable ion filters at atmospheric pressure. Figure 1 illustrates the operation of the PFAIMS. As a gas sample is introduced into the spectrometer it is ionized and the ions are transported through an ion filter towards a detector by a carrier gas. The ion filter is electronically tunable and the ion species U4.1.1 Downloaded from https://www.cambridge.org/core. University of Arizona, on 27 Jul 2018 at 06:47:27, subject to the Cambridge Core terms of use, available at https://www.cambridge.org/core/terms. https://doi.org/10.1557/PROC-729-U4.1
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