Width-Modulated Microfluidic Columns for Gas Separations

Shakeel, Hamza; Wang, Dong; Heflin, James R.; Agah, Masoud

doi:10.1109/jsen.2014.2326593

Cited by 16 publications

(8 citation statements)

References 29 publications

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“…Over the past couple of decades, significant progress has been made in column miniaturization using MEMS technology and in their stationary phase coating . The advantages of the MEMS columns include batch fabrication and lower cost, fast analysis time with less power consumption, and decreasing the dead volume through monolithic integration with other components of μGCs. − Using columns fabricated by a deep reactive ion etching technique, our group has developed multicapillary columns, width-modulated columns, semipacked columns, and recently, density-modulated semipacked columns. − Our group, as well as others, have shown that successful separation of multianalyte gas mixtures can be achieved using 0.5–3 m long columns. , While the early reports showed columns with the number of theoretical plates close <2000 plates/m, over the past few years, more columns have been demonstrated that can achieve efficiencies beyond 5000 plates/m. ,, A comprehensive review of MEMS columns and future trends can be found in several review articles. ,, One example of significant research includes the report of the University of Illinois with 16 500 theoretical plates for 3 m-long microfabricated columns coated with OV-5 connected to 0.5 m long fused-silica tubes. The performance of this column was evaluated for the detection of 16 organic volatile compounds mixture .…”

Section: Introductionmentioning

confidence: 99%

Parallel Ionic Liquid Semi-Packed Microfabricated Columns for Complex Gas Analysis

2020

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The paper presents a parallel micro gas chromatography approach using three ionic liquid semipacked columns. Switching from single column to multiple parallel columns with different selectivity enhances the power of compound identification without increasing the analysis time. The columns are fabricated using microelectromechanical systems (MEMS) technology containing an array of microfabricated pillars. The columns are 1 m-long and 240 μm-deep with four pillars per row. All columns were functionalized with ionic liquid stationary phases using a modified static coating technique and demonstrated the number of theoretical plates between 5000 and 8300 per meter. The chip performance was investigated with four different samples: (1) a mixture of C7–C30 saturated alkanes, (2) a multianalyte mixture consisting of 20 compounds ranging from 80 to 238 °C in boiling point, (3) a mixture of five organic chemicals with varying degrees of polarity, and (4) 46-compounds mixture containing all the chemicals in the first three samples. The individual columns separated 75%–100% of the first three samples but failed to distinguish all 46 compounds due to coeluting analytes; however, the parallel configuration provided more retention time information by which all the compounds in all samples were fully determined.

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Section: Introductionmentioning

confidence: 99%

Parallel Ionic Liquid Semi-Packed Microfabricated Columns for Complex Gas Analysis

2020

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“…As a very thin thickness of the stationary phase film is assumed, the contribution of band-broadening due to diffusion in the stationary phase can be neglected. Therefore, the 3rd term in Equation (1) can be ignored to simplify the calculation [58]. An n -hexane was used to determine the average carrier gas velocity for calculating the corresponding HETP value of the GC columns.…”

Section: Resultsmentioning

confidence: 99%

Development of Open-Tubular-Type Micro Gas Chromatography Column with Bump Structures

Lee

Lim

2019

Sensors

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Gas chromatography (GC) is the chemical analysis technique most widely used to separate and identify gas components, and it has been extensively applied in various gas analysis fields such as non-invasive medical diagnoses, indoor air quality monitoring, and outdoor environmental monitoring. Micro-electro-mechanical systems (MEMS)-based GC columns are essential for miniaturizing an integrated gas analysis system (Micro GC system). This study reports an open-tubular-type micro GC (μ-GC) column with internal bump structures (bump structure μ-GC column) that substantially increase the interaction between the gas mixture and a stationary phase. The developed bump structure μ-GC column, which was fabricated on a 2 cm × 2 cm μ-GC chip and coated with a non-polar stationary phase, is 1.5 m-long, 150 μm-wide, and 400 μm-deep. It has an internal microfluidic channel in which the bumps, which are 150 μm diameter half-circles, are alternatingly disposed to face each other on the surface of the microchannel. The fabricated bump structure μ-GC column yielded a height-equivalent-to-a-theoretical-plate (HETP) of 0.009 cm (11,110 plates/m) at an optimal carrier gas velocity of 17 cm/s. The mechanically robust bump structure μ-GC column proposed in this study achieved higher separation efficiency than a commercially available GC column and a typical μ-GC column with internal post structures classified as a semi-packed-type column. The experimental results demonstrate that the developed bump structure μ-GC column can separate a gas mixture completely, with excellent separation resolution for formaldehyde, benzene, toluene, ethylbenzene, and xylene mixture, under programmed operating temperatures.

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“…Among the shape of the column and implemented pillars or none, some researchers tried different layouts including width modulation [40], multi-capillary [41], and partially buried channel [42].…”

Section: Geometrymentioning

confidence: 99%

MEMS Devices for Miniaturized Gas Chromatography

Azzouz¹,

Bachari²

2018

MEMS Sensors - Design and Application

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In the era of the Internet of Things, the need for mobile devices able to analyze accurately real samples with sometimes very small volumes is a must. Gas chromatography (GC) is a common laboratory technique widely used for analyzing semi-volatile and volatile compounds. However, this technique is not suitable to be used outside labs. The development of micro-machined processes encouraged the development of miniaturized gas chromatographs. This chapter focuses on the recent development in the field of miniaturized gas chromatography and its component up to the present in various fields of analyses.

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Width-Modulated Microfluidic Columns for Gas Separations

Cited by 16 publications

References 29 publications

Parallel Ionic Liquid Semi-Packed Microfabricated Columns for Complex Gas Analysis

Parallel Ionic Liquid Semi-Packed Microfabricated Columns for Complex Gas Analysis

Development of Open-Tubular-Type Micro Gas Chromatography Column with Bump Structures

MEMS Devices for Miniaturized Gas Chromatography

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