Semipacked columns with atomic layer-deposited alumina as a stationary phase

Shakeel, Hamza; Rice, Gary W.; Agah, Masoud

doi:10.1016/j.snb.2014.06.017

Cited by 39 publications

(28 citation statements)

References 31 publications

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“…To demonstrate the wafer-level coating for HDSPCs architecture, we fabricated 1m-long, 145 µm-wide, 155 µm-deep HDSPCs with 10.5 µm circular posts and 7.5µm postspacing using standard MEMS processes. The fabrication of these columns is similar to our recently published work [25] and performed on a 4 inch-wide and 500 µm-thick single side polished silicon wafer. Briefly, the RCA cleaned wafer is first primed using HMDS followed by heating at 110 °C for 4 minutes.…”

Section: Experimental a Column Fabricationmentioning

confidence: 99%

“…Moreover, the enhancement of separation capability of CNTs and graphene functionalized PDMS stationary phases is recently reported for both open-tubular and semi-packed columns [23]. Atomic layer deposition (ALD) based coating, recently developed by our group for SPCs (1m-long, 190 µm-wide with 20 µm-circular micropillars and 20 µm-post spacing), also enables the realization of a highly reproducible, conformal, easy to use, mechanically and thermally stable separation films [24,25]. This stationary phase deposition technique has been successfully employed by our group for a monolithically integrated separation and detection module [24] and a single chip GC system (injection, separation, and detection) [26].…”

Section: Introductionmentioning

confidence: 99%

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High density semipacked separation columns with optimized atomic layer deposited phases

Shakeel

Agah

2017

Sensors and Actuators B: Chemical

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This paper reports the development of a new class of high-performance microfabricated separation columns called high-density semi-packed columns (HDSPCs). These columns are realized by using a meter long and 145 µm-wide silicon microchannel design with embedded circular micropillars (15 µm diameters) and 5 µm post spacing (perpendicular to the gas flow). The HDSPCs are coated using our previously developed atomic layer deposition (ALD) based aluminium oxide and silane functionalized thin adsorben t film. Moreover, in this study we optimize both ALD deposition temperature (100 ° C, 150 °C, 250 ° C and 300 ° C) and film thickness (10 nm, 20 nm and 30 nm) using different chromatographic parameters (plate number, peak-to-peak resolution, and separation factor). Additionally, the thermodynamic characteristics of these silane functionalized/ALD films are also studied using Van't Hoff plots. These columns with optimized stationary phases are able to provide ≈8,000 effective plates/meter and

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Section: Experimental a Column Fabricationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

High density semipacked separation columns with optimized atomic layer deposited phases

Shakeel

Agah

2017

Sensors and Actuators B: Chemical

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“…In this article, we demonstrate the formation of alcohol based monolayers on silicon oxide surfaces in polar aprotic solvents. The modification of surfaces with organic monolayers has been of great importance in the fields of electronics, [1][2][3][4] microfluidics, [4][5][6][7][8][9] separation sciences, [10][11][12][13] electrochemical sensing, [14][15][16] and biological interfaces. [17][18][19][20][21][22][23] Precursors based on silanes and phosphonic acids 17,21,[24][25][26] have been widely utilized to form organic monolayers on silicon oxide surfaces.…”

Section: Introductionmentioning

confidence: 99%

Covalent Surface Modification of Silicon Oxides with Alcohols in Polar Aprotic Solvents

Lee

Gates

2017

Langmuir

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Alcohol-based monolayers were successfully formed on the surfaces of silicon oxides through reactions performed in polar aprotic solvents. Monolayers prepared from alcohol-based reagents have been previously introduced as an alternative approach to covalently modify the surfaces of silicon oxides. These reagents are readily available, widely distributed, and are minimally susceptible to side reactions with ambient moisture. A limitation of using alcohol-based compounds is that previous reactions required relatively high temperatures in neat solutions, which can degrade some alcohol compounds or could lead to other unwanted side reactions during the formation of the monolayers. To overcome these challenges, we investigate the condensation reaction of alcohols on silicon oxides carried out in polar aprotic solvents. In particular, propylene carbonate has been identified as a polar aprotic solvent that is relatively nontoxic, readily accessible, and can facilitate the formation of alcohol-based monolayers. We have successfully demonstrated this approach for tuning the surface chemistry of silicon oxide surfaces with a variety of alcohol containing compounds. The strategy introduced in this research can be utilized to create silicon oxide surfaces with hydrophobic, oleophobic, or charged functionalities.

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“…[1][2][3][4] The increasing demand for onsite monitoring of VOCs has led to the development of micro gas chromatography (μGC) systems providing the desirable features of smaller size and higher portability, lower power consumption, and minimal production and maintenance costs. μGCs are realized by employing the microelectromechanical systems (MEMS) technology which enables the miniaturization of key GC components, namely, preconcentrators, [5][6][7][8] separation columns, [9][10][11][12][13][14][15] and detectors. [16][17][18] Since its first conceptual demonstration by Terry et al, 19 the trend followed by the research community to realize a complete μGC has been the fabrication of individual μGC components and their hybrid integration.…”

Section: Introductionmentioning

confidence: 99%

“…The dimensions chosen for the μSC and μDPID in the module are based on our previous work. 11,31 A mixture of VOCs is introduced through the inlet port of the chip which travels through the semi-packed μSC with an inert carrier gas called the mobile phase. The inner surface of the μSC is covered with a finely controllable stationary phase which is a silane-treated alumina layer as established in our previous work.…”

Section: Introductionmentioning

confidence: 99%

GC-on-chip: integrated column and photoionization detector

2015

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This paper reports a unique GC-on-chip module comprising a monolithically integrated semi-packed micro separation column (μSC) and a highly sensitive micro helium discharge photoionization detector (μDPID). While semi-packed μSC with atomic layer deposited (ALD) alumina as a stationary phase provides high separation performance, the μDPID implemented for the first time in a silicon-glass architecture inherits the desirable features of being universal, non-destructive, low power consumption (1.4 mW), and responsive. The integrated chip is 1.5 cm × 3 cm in size and requires a two-mask fabrication process. Monolithic integration alleviates the need for transfer lines between the column and the detector which improves the performance of the individual components with overall reduced fabrication and implementation costs. The chip is capable of operating under the isothermal as well as temperature and flow programming conditions to achieve rapid chromatographic analysis. The chip performance was investigated with two samples: 1) a multi-analyte gas mixture consisting of eight compounds ranging from 98 °C to 174 °C in boiling point and 2) a mixture containing higher alkanes (C9-C12). Our experiments indicate that the chip is capable of providing rapid chromatographic separation and detection of these compounds (<1 min) through the optimization of flow and temperature programming conditions. The GC-on-chip demonstrated a minimum detection limit of ~10 pg which is on a par with the widely used destructive flame ionization detector (FID).

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Semipacked columns with atomic layer-deposited alumina as a stationary phase

Cited by 39 publications

References 31 publications

High density semipacked separation columns with optimized atomic layer deposited phases

High density semipacked separation columns with optimized atomic layer deposited phases

Covalent Surface Modification of Silicon Oxides with Alcohols in Polar Aprotic Solvents

GC-on-chip: integrated column and photoionization detector

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