Evaluating the dynamic retention capacities of microfabricated vapor preconcentrators as a function of flow rate

Sukaew, Thitiporn; Zellers, Edward T.

doi:10.1016/j.snb.2013.03.105

Cited by 15 publications

(16 citation statements)

References 42 publications

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“…Our explanation relies on the desorption temperature values herein used, somewhat hindered by the microfluidic connections capable to withstand maximum temperature of 180ºC. In fact, these values are clearly lower than those commonly reported in the literature for hexane desorption on MFI type zeolites around 300ºC [38]; or even those used on microconcentrators coated with activated carbons, around 225ºC [16][17][18][19]. It could be concluded that the operational performance could be notably improved by using high-temperature microfluidic connections.…”

Section: Standard Characterization Of the Microconcentratorsmentioning

confidence: 79%

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Zeolite based microconcentrators for volatile organic compounds sensing at trace-level: fabrication and performance

Almazan

Pellejero

Morales

et al. 2016

J. Micromech. Microeng.

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A novel 6-step microfabrication process is proposed in this work to prepare microfluidic devices with integrated zeolite layers. In particular, microfabricated preconcentrators designed for volatile organic compounds (VOC) sensing applications are fully described. The main novelty of this work is the integration of the pure siliceous MFI type zeolite (silicalite-1) polycrystalline layer, i.e 4.0 ± 0.5 µm thick, as active phase, within the microfabrication process just before the anodic bonding step. Following this new procedure, Si microdevices with an excellent distribution of the adsorbent material, integrated resistive heaters and Pyrex caps have been obtained. Firstly, the microconcentrator performance has been assessed by means of the normal hexane breakthrough curves as a function of sampling and desorption flowrates, temperature and micropreconcentrator design. In a step further, the best preconcentrator device has been tested in combination with downstream Si based microcantilevers deployed as VOC detectors. Thus, a preliminar evaluation of the improvement on detection sensitivity by silicalite-1 based microconcentrators is presented.

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Section: Standard Characterization Of the Microconcentratorsmentioning

confidence: 79%

“…From the first portion of the breakthrough curve, i.e. up to C/C 0 =0.05 where the sorption active centers are in clear excess, mass transfer kinetic coefficient of 6184 min -1 has been calculated following the procedure detailed elsewhere [18].…”

Section: Standard Characterization Of the Microconcentratorsmentioning

confidence: 99%

Zeolite based microconcentrators for volatile organic compounds sensing at trace-level: fabrication and performance

Almazan

Pellejero

Morales

et al. 2016

J. Micromech. Microeng.

View full text Add to dashboard Cite

show abstract

“…Nevertheless, the common point of all these definitions is its dependence on several parameters such as the sharp and volume of preconcentrator, the adsorption and desorption flows, the pressure drop and the heating rate. Some authors [9,10,11] define the PF as the ratio between peaks area obtained with and without preconcentrator ("chromatography approach"). This approach supposes to have a peak even without preconcentrator, i.e.…”

Section: Definition Of Preconcentration Factor (Pf)mentioning

confidence: 99%

“…The fundamental theory of gas adsorption on solid is the first model implemented; it was proposed by Langmuir [9,12,13,14] in 1918 and is based on three key hypotheses:…”

Section: Langmuir Theorymentioning

confidence: 99%

Preconcentration Modeling for the Optimization of a Micro Gas Preconcentrator Applied to Environmental Monitoring

et al. 2015

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This paper presents the optimization of a micro gas preconcentrator (μ-GP) system applied to atmospheric pollution monitoring, with the help of a complete modeling of the preconcentration cycle. Two different approaches based on kinetic equations are used to illustrate the behavior of the micro gas preconcentrator for given experimental conditions. The need for high adsorption flow and heating rate and for low desorption flow and detection volume is demonstrated in this paper. Preliminary to this optimization, the preconcentration factor is discussed and a definition is proposed.

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“…Members of our group have reported on a number of μGC and μGC × μGC components and systems in recent years [37][38][39][40][41][42][43][44][45][46][47][48][49][50] . We have also developed automated prototype instruments containing μGC systems for measuring low-to sub-ppb concentrations of trichloroethylene (TCE) in vapor-intrusion impacted homes 51,52 , and markers of explosives for transportation security 53,54 .…”

Section: Introductionmentioning

confidence: 99%

Compact prototype microfabricated gas chromatographic analyzer for autonomous determinations of VOC mixtures at typical workplace concentrations

et al. 2018

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This report concerns a benchtop prototype instrument containing a gas chromatographic microanalytical system (μGC) designed for the selective determination of multiple airborne volatile organic compounds (VOCs) at concentrations in the vicinity of recommended occupational exposure limits. The core microsystem consists of a set of discrete Si-microfabricated devices: a dualcavity, adsorbent-packed micro-preconcentrator-focuser (μPCF) chip that quantitatively captures and thermally desorbs/injects VOCs with vapor pressures between~0.03 and 13 kPa; tandem micro-column (μcolumn) chips with cross-linked PDMS wall-coated stationary phases capable of temperature-programmed separations; and an integrated array of five μchemiresistors (μCR) coated with different thiolate-monolayer protected gold nanoparticle (MPN) interface films that quantifies and further differentiates among the analytes by virtue of the response patterns generated. Other key components include a pre-trap for low-volatility interferences, a split-flow injection valve, and an onboard He carrier-gas canister. The assembled unit measures 19 × 30 × 14 cm, weighs~3.5 kg, operates on AC power, and is laptop/LabVIEW controlled. Component-and system-level tests of performance demonstrated injection bandwidths o1 s, a μcolumn capacity of ≥ 8 μg injected mass, linear calibration curves, no humidity effects, excellent medium-term (that is, 1 week) reproducibility, autonomous operation for 8 h, detection limits below Threshold Limit Values (TLV) for 10 mL air samples collected in 1 min, and response patterns that enhanced vapor recognition. The determination of a 17-VOC mixture in the presence of seven interferences was performed in 4 min. Results augur well for adapting the microsystem to an all-MEMS wearable μGC currently under parallel development.

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Evaluating the dynamic retention capacities of microfabricated vapor preconcentrators as a function of flow rate

Cited by 15 publications

References 42 publications

Zeolite based microconcentrators for volatile organic compounds sensing at trace-level: fabrication and performance

Zeolite based microconcentrators for volatile organic compounds sensing at trace-level: fabrication and performance

Preconcentration Modeling for the Optimization of a Micro Gas Preconcentrator Applied to Environmental Monitoring

Compact prototype microfabricated gas chromatographic analyzer for autonomous determinations of VOC mixtures at typical workplace concentrations

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