Hydrodynamic evaluation of gas testing chamber: Simulation, experiment

Annanouch, Fatima Ezahra; Bouchet, Gilles; Perrier, Pierre; Morati, Nicolas; Reynard-Carette, C.; Aguir, Khalifa; Martini-Laithier, Virginie; Bendahan, Marc

doi:10.1016/j.snb.2019.04.023

Cited by 25 publications

(25 citation statements)

References 29 publications

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“…This step helps us to improve our understanding of the sensor’s characteristics and to define its performances, including the concentration detection range, the optimal working temperature, and the influence of humidity on the sensor’s responses. Since the transdermal measurements will be carried out in a very small cell, as shown in Figure 3 b, we have designed and fabricated a testing chamber ( Figure 7 ) to remain near to the real measurement conditions, with the following technical characteristics: a small volume of 2.35 × 10 −3 L; negligible dead volumes; homogeneous gas concentration in the test chamber; and a low gas flow rate around the sensor (more details are in [ 25 ]).…”

Section: Resultsmentioning

confidence: 99%

“…It contains one membrane of 400 μm × 400 μm, in which interdigitated electrodes and two heaters in platinum were designed using clean room facilities and various microfabrication steps. The gap between the electrodes and their width is 4 μm, the resistance of each heater is 100 Ω, and the temperature coefficient is 3 × 10 −3 /K [ 25 , 26 ].…”

Section: Methodsmentioning

confidence: 99%

“…A small testing chamber with a total volume of 2.35 × 10 −3 L was designed with the aim to approach transdermal detection conditions (more details are in [ 25 ]). The target gas (ethanol) was delivered to the testing chamber ( Figure 2 ) via a gas generation–dilution system, making it possible to generate gases or gas mixtures in a controlled atmosphere.…”

Section: Methodsmentioning

confidence: 99%

“…More details regarding the effect of the chamber volume on the gas flow rate are provided in ref. [ 25 ]. The gas sensing measurements were achieved by monitoring, in real time, the electrical resistance of the sensor via a Keithley 2450 source meter.…”

Section: Methodsmentioning

confidence: 99%

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Embedded Transdermal Alcohol Detection via a Finger Using SnO2 Gas Sensors

Annanouch

Martini-Laithier

Fiorido

et al. 2021

Sensors

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In this paper, we report the fabrication and characterization of a portable transdermal alcohol sensing device via a human finger, using tin dioxide (SnO2) chemoresistive gas sensors. Compared to conventional detectors, this non-invasive technique allowed us the continuous monitoring of alcohol with low cost and simple fabrication process. The sensing layers used in this work were fabricated by using the reactive radio frequency (RF) magnetron sputtering technique. Their structure and morphology were investigated by means of X-ray spectroscopy (XRD) and scanning electron microscopy (SEM), respectively. The results indicated that the annealing time has an important impact on the sensor sensitivity. Before performing the transdermal measurements, the sensors were exposed to a wide range of ethanol concentrations and the results displayed good responses with high sensitivity, stability, and a rapid detection time. Moreover, against high relative humidity (50% and 70%), the sensors remained resistant by showing a slight change in their gas sensing performances. A volunteer (an adult researcher from our volunteer group) drank 50 mL of tequila in order to realize the transdermal alcohol monitoring. Fifteen minutes later, the volunteer’s skin started to evacuate alcohol and the sensor resistance began to decline. Simultaneously, breath alcohol measurements were attained using a DRAGER 6820 certified breathalyzer. The results demonstrated a clear correlation between the alcohol concentration in the blood, breath, and via perspiration, which validated the embedded transdermal alcohol device reported in this work.

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Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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Embedded Transdermal Alcohol Detection via a Finger Using SnO2 Gas Sensors

Annanouch

Martini-Laithier

Fiorido

et al. 2021

Sensors

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“…According to Smith et al [43], this humidity sensing effect in graphene/SiO 2 layers is attributed to the interaction of graphene layer and impurity bands in SiO 2 , with the H 2 O electrostatic dipole moment. In effect, a (9) t res = t 90 (10) t rec = t 10 − t max Fig.…”

Section: Device Testing Of Gfetmentioning

confidence: 99%

Influence of chamber design on the gas sensing performance of graphene field-effect-transistor

et al. 2020

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We report on the influence of chamber design on the gas sensing performance of a graphene field-effect-transistor (GFET). A conventional chamber (V = 400 ml) and a cap chamber (V = 1 ml), were used to perform dynamic measurements on a GFET. To gain a-priori knowledge on the gas flow in the chambers, Naiver-Stokes and convection-diffusion equations were numerically-solved using COMSOL Multiphysics. We numerically and experimentally observed two main factors that can affect the GFET performance: (1) the gas flow direction through the chamber and (2) the chamber volume. At 5-min exposure time, at least 200% higher GFET sensitivity was calculated from the cap chamber, which is expected since the conventional chamber is 400 times larger. Interestingly, even when the conventional chamber is fully saturated (at 90-min exposure time), the GFET sensitivity in the cap chamber is still better by 28.57%. We attributed this behavior to the swirling vapor flow in the cap chamber brought about by the U-shaped path. This effect causes multiple interaction of H 2 O molecules with the GFET, resulting to higher computed sensitivity. However, at higher relative humidity, the GFET becomes populated, reducing the number of H 2 O molecules that can re-interact with the sensor. In terms of GFET transient characteristics, a 154% and 86.9% faster response and recovery, respectively, were observed in the cap-design. This was due to its smaller volume that minimized poorly purged region in the chamber. But if the chambers have the same volumes, we may infer a faster GFET response and recovery from the conventional chamber where the gas flow is unperturbed. These results could contribute in designing a time efficient and cost-effective gas sensing system.

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