Influence of gaseous species transport on the response of solid state gas sensors within enclosures

Lezzi, Adriano Maria; Beretta, Gian Paolo; Comini, Elisabetta; Faglia, Guido; Galli, G

doi:10.1016/s0925-4005(01)00805-x

Cited by 18 publications

(16 citation statements)

References 2 publications

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“…These response times were 5 to 25 times smaller than those in heated chambers [17]. This is attributed to two effects: (1) heated chambers are characterized by large volumes of almost stagnant fluid and peripheral position of the sensor and thus the response time is more a measurement of the transient concentration within the chamber rather than a characteristic feature of the device [19]. (2) Due to rapid inlet velocity of the impinging jet and resulting turbulence here, the analyte mass flux to the sensing film of the present device was considerably higher.…”

Section: Resultsmentioning

confidence: 99%

“…These promising results, however, were obtained in large heated chambers and simulated breath conditions. The application of such nanoparticles as acetone detectors in portable devices is not trivial [18] as reaching sufficiently high temperatures (300–450 °C) at reasonable power consumption requires a locally heated substrate that may result in inhomogeneous temperatures and concentration profiles within the sensing film [19]. Thus, the development of a portable device for breath acetone detection is still challenging [8] but quite attractive.…”

Section: Introductionmentioning

confidence: 99%

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Breath acetone monitoring by portable Si:WO3 gas sensors

Righettoni

Tricoli

Gass

et al. 2012

Analytica Chimica Acta

283

206

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Breath analysis has the potential for early stage detection and monitoring of illnesses to drastically reduce the corresponding medical diagnostic costs and improve the quality of life of patients suffering from chronic illnesses. In particular, the detection of acetone in the human breath is promising for non-invasive diagnosis and painless monitoring of diabetes (no finger pricking). Here, a portable acetone sensor consisting of flame-deposited and in situ annealed, Si-doped epsilon-WO 3 nanostructured films was developed. The chamber volume was miniaturized while reaction-limited and transport-limited gas flow rates were identified and sensing temperatures were optimized resulting in a low detection limit of acetone (~20 ppb) with short response (10-15 s) and recovery times (35-70 s). Furthermore, the sensor signal (response) was robust against variations of the exhaled breath flow rate facilitating application of these sensors at realistic relative humidities (80-90%) as in the human breath. The acetone content in the breath of test persons was monitored continuously and compared to that of state-of-the-art proton transfer reaction mass spectrometry (PTR-MS). Such portable devices can accurately track breath acetone concentration to become an alternative to more elaborate breath analysis techniques.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Breath acetone monitoring by portable Si:WO3 gas sensors

Righettoni

Tricoli

Gass

et al. 2012

Analytica Chimica Acta

283

206

View full text Add to dashboard Cite

show abstract

“…It implies that the effective concentration experienced by the sensor is different according to the total flow rate for the analyte injection with the same concentration. These phenomena may result from the difference in the effective concentration induced by the kinetic transport of the analyte-carrying flow, as previously reported [11]. Although the higher total flow rate is more ideal, the available flow rate is limited practically within the maximum magnitude of the used MFCs.…”

Section: Gas-sensing Characteristicsmentioning

confidence: 67%

“…Recently, simulation studies on flow dynamics were performed to examine the space distribution of analyte molecules within a measurement chamber and its time-dependent evolution [11][12][13]. From these transport phenomena analyses, the geometrical parameters such as chamber volume and shape were found to give a great influence on the gas-sensing characteristics because of the direct correlation of sensor response to the local analyte concentration on the sensor surface rather than to the average value within the chamber.…”

Section: Introductionmentioning

confidence: 99%

Gas sensor measurement system capable of sampling volatile organic compounds (VOCs) in wide concentration range

Kim

Yang

et al. 2007

Sensors and Actuators B: Chemical

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“…Chamber 3 shows better performance compared to chambers 1 and 2. Hence, inlet and outlet positions also influence the performance of the sensor chamber [15].…”

Section: Effect Of Position and Number Of Inlets/outlet On Flow Distrmentioning

confidence: 99%

Performance optimisation of a sensing chamber using fluid dynamics simulation for electronic nose applications

Dohare¹,

Bagchi²,

Bhondekar³

2020

Turk J Elec Eng & Comp Sci

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The sensor chamber plays a significant role in order to improve the performance of an electronic nose in terms of stability, repeatability, reproducibility, and sensitivity. Fluid dynamics simulations of six different configurations of 3D sensing chambers are presented to facilitate the efficient design of an electronic nose system comprising 64 sensor arrays. Numerical simulations were carried out to investigate the gas (zero air) flow behaviour inside these chambers under steady-state conditions for velocities ranging from 0.1 to 2 m/s using ANSYS software. Design optimisation was performed in terms of area coverage, velocity, and mass fraction. The results show that the area coverage and mass fraction distribution increase with flow velocity. The sensor chambers achieved more than 70% flow coverage over the sensors at a velocity beyond 0.7 m/s. In further chamber designs, four baffles were introduced at different positions in a two inlet and one outlet chamber model to enhance the performance of the chamber. The effect of baffle positions in the flow distribution was investigated through numerical simulations. Chamber designs with the introduction of baffles achieved a maximum mass fraction. Thus, the insertion of baffles improved the area coverage and mass fraction. In addition, to show the real-time applicability further simulations were performed in the optimised sensor chamber.

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Influence of gaseous species transport on the response of solid state gas sensors within enclosures

Cited by 18 publications

References 2 publications

Breath acetone monitoring by portable Si:WO3 gas sensors

Breath acetone monitoring by portable Si:WO3 gas sensors

Gas sensor measurement system capable of sampling volatile organic compounds (VOCs) in wide concentration range

Performance optimisation of a sensing chamber using fluid dynamics simulation for electronic nose applications

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