Identifying volatile organic compounds by determining their diffusion and surface adsorption parameters in microfluidic channels

Hossein‐Babaei, Faramarz; Zare, Ali Hooshyar; Ghafarinia, Vahid; Erfantalab, Sobhan

doi:10.1016/j.snb.2015.06.014

Cited by 17 publications

(14 citation statements)

References 29 publications

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“…In a follow-up work [ 44 ], two different devices were fabricated and tested by the same authors: device A, which comprises of a generic Tin Oxide (SnO 2 ) chemiresistive gas sensor connected to a bundle of cylindrical channels, with diameters of 50 μm and length of 5 cm; and device B, composed by a similar gas sensor connected to a single channel of much larger diameter (1000 μm) and shorter length (2 cm). The operation method is identical to the previous work reported by the authors [ 10 ], with the open ends of both channels connected to the analyte-filled chamber.…”

Section: Microfluidic Gas Sensing Devices Based On Electrical Tranmentioning

confidence: 99%

Microfluidics in Gas Sensing and Artificial Olfaction

Rebordão

Palma

Roque

2020

Sensors

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Rapid, real-time, and non-invasive identification of volatile organic compounds (VOCs) and gases is an increasingly relevant field, with applications in areas such as healthcare, agriculture, or industry. Ideal characteristics of VOC and gas sensing devices used for artificial olfaction include portability and affordability, low power consumption, fast response, high selectivity, and sensitivity. Microfluidics meets all these requirements and allows for in situ operation and small sample amounts, providing many advantages compared to conventional methods using sophisticated apparatus such as gas chromatography and mass spectrometry. This review covers the work accomplished so far regarding microfluidic devices for gas sensing and artificial olfaction. Systems utilizing electrical and optical transduction, as well as several system designs engineered throughout the years are summarized, and future perspectives in the field are discussed.

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Section: Microfluidic Gas Sensing Devices Based On Electrical Tranmentioning

confidence: 99%

Microfluidics in Gas Sensing and Artificial Olfaction

Rebordão

Palma

Roque

2020

Sensors

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“…The response of the gas sensor incorporated in the microcavity located at the channel end ( Fig. 1a ) is continuously recorded from t = -5 s to t = 200 s. The relationship between such temporal response profiles and the diffusion rates through the channel has been the subject of discussion in a number of publications from our laboratory 52 53 54 , but in the present work such responses are utilized only for comparing the permeabilities of the test and control microchannels to the target gas.…”

Section: Resultsmentioning

confidence: 99%

The selective flow of volatile organic compounds in conductive polymer-coated microchannels

Hossein‐Babaei

Zare

2017

Sci Rep

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Many gaseous markers of critical biological, physicochemical, or industrial occurrences are masked by the cross-sensitivity of the sensors to the other active components present at higher concentrations. Here, we report the strongly selective diffusion and drift of contaminant molecules in air-filled conductive polymer-coated microfluidic channels for the first time. Monitoring the passage of different target molecules through microchannels coated with Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) revealed that contaminants such as hexane, benzene, and CO pass through the channel unaffected by the coating while methanol, ethanol, and partly acetone are blocked. The observations are explained with reference to the selective interactions between the conductive polymer surface and target gas molecules amplified by the large wall/volume ratio in microchannels. The accumulated quantitative data point at the hydrogen bonding as the mechanism of wall adsorption; dipole-dipole interactions are relatively insignificant. The presented model facilitates a better understanding of how the conductive polymer-based chemical sensors operate.

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“…The working principle of these devices is rooted on chromatographic columns, employed in macro- and microanalytical tools. Nonetheless, microfluidic channels normally have lengths several magnitudes shorter (<10 cm), do not require a carrier gas tank, and can operate at room temperature [ 255 ]. Molecular diffusion and surface physisorption of gas molecules are two physical properties with considerable span among species.…”

Section: Microanalytical Tools For Vocs Discriminationmentioning

confidence: 99%

“…According to literature, if a microfluidic channel with circular cross-section is considered, the concentration loss

due to the physisorption effect can be represented by the following expression [ 257 ]:

where

is the number of the surface adsorption sites available per unit volume of the channel,

is the effective channel depth, and

is generally defined as the physisorption constant, which is directly related to the nature of analytes. Combining the physisorption expression to the diffusion equation initially stated, the so-called diffusion-physisorption equation can be formulated, which gives the change in analytes concentration over time and along the microfluidic channel [ 255 , 257 ]:

…”

Section: Microanalytical Tools For Vocs Discriminationmentioning

confidence: 99%

“…For this reason, the selectivity and performance of microfluidic devices relies on the optimization of several factors, such as (i) channel’s geometry, (ii) coating of the channel walls, and (iii) environmental conditions (i.e., temperature and relative humidity) [ 254 ]. First of all, microfluidic devices normally incorporate straight channels of a few centimeters length, with either circular or square cross-sections [ 252 , 255 ]. Similar to chromatographic columns, design and geometrical properties of the channel are strategically selected to achieve the best selectivity, while ensuring acceptable response and recovery times [ 260 ].…”

Section: Microanalytical Tools For Vocs Discriminationmentioning

confidence: 99%

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Advancements in Microfabricated Gas Sensors and Microanalytical Tools for the Sensitive and Selective Detection of Odors

Ollé

Farré-Lladós

Casals‐Terré

2020

Sensors

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In recent years, advancements in micromachining techniques and nanomaterials have enabled the fabrication of highly sensitive devices for the detection of odorous species. Recent efforts done in the miniaturization of gas sensors have contributed to obtain increasingly compact and portable devices. Besides, the implementation of new nanomaterials in the active layer of these devices is helping to optimize their performance and increase their sensitivity close to humans’ olfactory system. Nonetheless, a common concern of general-purpose gas sensors is their lack of selectivity towards multiple analytes. In recent years, advancements in microfabrication techniques and microfluidics have contributed to create new microanalytical tools, which represent a very good alternative to conventional analytical devices and sensor-array systems for the selective detection of odors. Hence, this paper presents a general overview of the recent advancements in microfabricated gas sensors and microanalytical devices for the sensitive and selective detection of volatile organic compounds (VOCs). The working principle of these devices, design requirements, implementation techniques, and the key parameters to optimize their performance are evaluated in this paper. The authors of this work intend to show the potential of combining both solutions in the creation of highly compact, low-cost, and easy-to-deploy platforms for odor monitoring.

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Identifying volatile organic compounds by determining their diffusion and surface adsorption parameters in microfluidic channels

Cited by 17 publications

References 29 publications

Microfluidics in Gas Sensing and Artificial Olfaction

Microfluidics in Gas Sensing and Artificial Olfaction

The selective flow of volatile organic compounds in conductive polymer-coated microchannels

Advancements in Microfabricated Gas Sensors and Microanalytical Tools for the Sensitive and Selective Detection of Odors

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