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Zeitschriftenartikel zum Thema „Gas microsensors“

Autor: Grafiati

Veröffentlicht am 25. Mai 2024

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1

Sandfeld, Tobias, Louise Vinther Grøn, Laura Munoz, Rikke Louise Meyer, Klaus Koren, and Jo Philips. "Considerations on the use of microsensors to profile dissolved H2 concentrations in microbial electrochemical reactors." PLOS ONE 19, no. 1 (2024): e0293734. http://dx.doi.org/10.1371/journal.pone.0293734.

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Measuring the distribution and dynamics of H2 in microbial electrochemical reactors is valuable to gain insights into the processes behind novel bioelectrochemical technologies, such as microbial electrosynthesis. Here, a microsensor method to measure and profile dissolved H2 concentrations in standard H-cell reactors is described. Graphite cathodes were oriented horizontally to enable the use of a motorized microprofiling system and a stereomicroscope was used to place the H2 microsensor precisely on the cathode surface. Profiling was performed towards the gas-liquid interface, while preserving the electric connections and flushing the headspace (to maintain anoxic conditions) and under strict temperature control (to overcome the temperature sensitivity of the microsensors). This method was tested by profiling six reactors, with and without inoculation of the acetogen Sporomusa ovata, at three different time points. H2 accumulated over time in the abiotic controls, while S. ovata maintained low H2 concentrations throughout the liquid phase (< 4 μM) during the whole experimental period. These results demonstrate that this setup generated insightful H2 profiles. However, various limitations of this microsensor method were identified, as headspace flushing lowered the dissolved H2 concentrations over time. Moreover, microsensors can likely not accurately measure H2 in the immediate vicinity of the solid cathode, because the solids cathode surface obstructs H2 diffusion into the microsensor. Finally, the reactors had to be discarded after microsensor profiling. Interested users should bear these considerations in mind when applying microsensors to characterize microbial electrochemical reactors.

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2

Jung, Dong Geon, Junyeop Lee, Jin Beom Kwon, Bohee Maeng, Hee Kyung An, and Daewoong Jung. "Low-Voltage-Driven SnO2-Based H2S Microsensor with Optimized Micro-Heater for Portable Gas Sensor Applications." Micromachines 13, no. 10 (2022): 1609. http://dx.doi.org/10.3390/mi13101609.

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To realize portable gas sensor applications, it is necessary to develop hydrogen sulfide (H2S) microsensors capable of operating at lower voltages with high response, good selectivity and stability, and fast response and recovery times. A gas sensor with a high operating voltage (>5 V) is not suitable for portable applications because it demands additional circuitry, such as a charge pump circuit (supply voltage of common circuits is approximately 1.8–5 V). Among H2S microsensor components, that is, the substrate, sensing area, electrode, and micro-heater, the proper design of the micro-heater is particularly important, owing to the role of thermal energy in ensuring the efficient detection of H2S. This study proposes and develops tin (IV)-oxide (SnO2)-based H2S microsensors with different geometrically designed embedded micro-heaters. The proposed micro-heaters affect the operating temperature of the H2S sensors, and the micro-heater with a rectangular mesh pattern exhibits superior heating performance at a relatively low operating voltage (3–4 V) compared to those with line (5–7 V) and rectangular patterns (3–5 V). Moreover, utilizing a micro-heater with a rectangular mesh pattern, the fabricated SnO2-based H2S microsensor was driven at a low operating voltage and offered good detection capability at a low H2S concentration (0–10 ppm), with a quick response (<51 s) and recovery time (<101 s).

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3

Siegal, M. P., W. G. Yelton, D. L. Overmyer, and P. P. Provencio. "Nanoporous Carbon Films for Gas Microsensors." Langmuir 20, no. 4 (2004): 1194–98. http://dx.doi.org/10.1021/la034460s.

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4

Vallejos, Stella, Zdenka Fohlerová, Milena Tomić, Isabel Gràcia, Eduard Figueras, and Carles Cané. "Room Temperature Ethanol Microsensors Based on Silanized Tungsten Oxide Nanowires." Proceedings 2, no. 13 (2018): 790. http://dx.doi.org/10.3390/proceedings2130790.

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Gas microsensors based on tungsten oxide (WO3-x) nanowires (NWs) silanized with APTES (3-aminopropyltriethoxysilane) are developed in this work. These surface modified microsensors are highly sensitive to ethanol at room temperature (RT) via photoactivation and show enhanced selectivity towards other volatile organic compounds (VOCs) including acetone and toluene.

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5

Siegal, M. P., and W. G. Yelton. "Nanoporous-Carbon Coatings for Gas-Phase Chemical Microsensors." Advances in Science and Technology 48 (October 2006): 161–68. http://dx.doi.org/10.4028/www.scientific.net/ast.48.161.

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Nanoporous-carbon (NPC) is compared directly to commonly-used polymers as a gassorbing coating material on surface acoustic wave (SAW) microsensor devices. The sensing capability of these materials is measured for volatile organic compounds (VOCs), toxic-industrial chemicals (TICs), and a chemical warfare agents (CWA) simulant. All of the coatings reversibly sorb and desorb the volatile VOC and TIC compounds, however, NPC outperforms the polymers over the range of analyte concentrations studied, especially at the lowest levels, by multiple ordersof- magnitude. Conversely, NPC has good retention properties for the semi-volatile CWA simulant tested, which while detrimental for use on a reversible SAW device, infers that NPC may be wellsuited as a preconcentrator coating for such analytes. NPC is a highly-disordered low-density carbon containing both nanopores and increased interplanar spacing between graphene sheet fragments, self-assembles using pulsed laser deposition, has no residual-stress at room temperature, is stable to 600 °C, and is chemically-inert in harsh environments. It has superior chemical and aging properties compared to the conventional polymer films used in microsensor devices.

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6

Penza, M., R. Rossi, M. Alvisi, et al. "Metalloporphyrin-Modified Carbon Nanotube Layers for Gas Microsensors." Sensor Letters 9, no. 2 (2011): 913–19. http://dx.doi.org/10.1166/sl.2011.1643.

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7

Bolotov, V. V., P. M. Korusenko, S. N. Nesov, et al. "Nanocomposite por-Si/SnOx layers formation for gas microsensors." Materials Science and Engineering: B 177, no. 1 (2012): 1–7. http://dx.doi.org/10.1016/j.mseb.2011.09.006.

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8

Swart, N., and A. Nathan. "Numerical study of heat transport in thermally isolated flow-rate microsensors." Canadian Journal of Physics 70, no. 10-11 (1992): 904–7. http://dx.doi.org/10.1139/p92-143.

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The temperature distributions in thermally isolated cantilever based flow-rate microsensors have been numerically calculated for different gas temperatures and gas velocities. In particular, we investigate the efficiency of heat transfer to the flowing gas and corresponding directions of heat flow in the system. The above analysis is based on a solution to the energy equation under appropriate boundary conditions. The equation was discretized using a control volume procedure, based on which an equivalent circuit was devised and subsequently simulated using a circuit simulator such as SPICE.

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9

Vittoriosi, Alice, Juergen J. Brandner, and Roland Dittmeyer. "Integrated temperature microsensors for the characterization of gas heat transfer." Journal of Physics: Conference Series 362 (May 23, 2012): 012021. http://dx.doi.org/10.1088/1742-6596/362/1/012021.

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10

Penza, M., R. Rossi, M. Alvisi, D. Suriano, and E. Serra. "Pt-modified carbon nanotube networked layers for enhanced gas microsensors." Thin Solid Films 520, no. 3 (2011): 959–65. http://dx.doi.org/10.1016/j.tsf.2011.04.178.

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11

Shoemaker, E. L., M. C. Vogt, F. J. Dudek, and T. Turner. "Gas microsensors using cyclic voltammetry with a cermet electrochemical cell." Sensors and Actuators B: Chemical 42, no. 1 (1997): 1–9. http://dx.doi.org/10.1016/s0925-4005(97)00178-0.

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12

Archanjo, Braulio S., Guilherme V. Silveira, Alem-Mar B. Goncalves, et al. "Fabrication of Gas Nanosensors and Microsensors via Local Anodic Oxidation." Langmuir 25, no. 1 (2009): 602–5. http://dx.doi.org/10.1021/la803105f.

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13

Urban, Sebastian, Vinayaganataraj Tamilselvi Sundaram, Jochen Kieninger, Gerald Urban, and Andreas Weltin. "Microsensor Electrodes for 3D Inline Process Monitoring in Multiphase Microreactors." Sensors 20, no. 17 (2020): 4876. http://dx.doi.org/10.3390/s20174876.

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We present an electrochemical microsensor for the monitoring of hydrogen peroxide direct synthesis in a membrane microreactor environment by measuring the hydrogen peroxide and oxygen concentrations. In prior work, for the first time, we performed in situ measurements with electrochemical microsensors in a microreactor setup. However, the sensors used were only able to measure at the bottom of the microchannel. Therefore, only a limited assessment of the gas distribution and concentration change over the reaction channel dimensions was possible because the dissolved gases entered the reactor through a membrane at the top of the channel. In this work, we developed a new fabrication process to allow the sensor wires, with electrodes at the tip, to protrude from the sensor housing into the reactor channel. This enables measurements not only at the channel bottom, but also along the vertical axis within the channel, between the channel wall and membrane. The new sensor design was integrated into a multiphase microreactor and calibrated for oxygen and hydrogen peroxide measurements. The importance of measurements in three dimensions was demonstrated by the detection of strongly increased gas concentrations towards the membrane, in contrast to measurements at the channel bottom. These findings allow a better understanding of the analyte distribution and diffusion processes in the microreactor channel as the basis for process control of the synthesis reaction.

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14

Grate, J. W., and D. A. Nelson. "Sorptive polymeric materials and photopatterned films for gas phase chemical microsensors." Proceedings of the IEEE 91, no. 6 (2003): 881–89. http://dx.doi.org/10.1109/jproc.2003.813575.

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15

Sabolsky, E. M., E. Ciftyurek, C. Wildfire, et al. "(Invited) Nano-Derived Microsensors for Monitoring Gas Species in Harsh-Environments." ECS Transactions 61, no. 2 (2014): 375–85. http://dx.doi.org/10.1149/06102.0375ecst.

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16

Kilpatrick, J. M., W. N. MacPherson, J. S. Barton, et al. "Measurement of unsteady gas temperature with optical fibre Fabry-Perot microsensors." Measurement Science and Technology 13, no. 5 (2002): 706–12. http://dx.doi.org/10.1088/0957-0233/13/5/308.

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17

Chen, Kun-Long, Yuan-Pin Tsai, and Nanming Chen. "Application of power current microsensors to current measurements in gas-insulated switchgears." Journal of the Chinese Institute of Engineers 35, no. 8 (2012): 1039–49. http://dx.doi.org/10.1080/02533839.2012.708553.

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18

Chao, S. "A simple laboratory procedure for packaging and testing part-fabricated gas microsensors." Measurement Science and Technology 7, no. 5 (1996): 737–41. http://dx.doi.org/10.1088/0957-0233/7/5/002.

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19

Vallejos, S., I. Gràcia, E. Figueras, N. Pizurova, J. Hubálek, and C. Cané. "ZnO-based Gas Microsensors Sensitive to CO at Room Temperature by Photoactivation." Procedia Engineering 168 (2016): 415–18. http://dx.doi.org/10.1016/j.proeng.2016.11.198.

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20

Kühne, S., M. Graf, A. Tricoli, F. Mayer, S. E. Pratsinis, and A. Hierlemann. "Wafer-level flame-spray-pyrolysis deposition of gas-sensitive layers on microsensors." Journal of Micromechanics and Microengineering 18, no. 3 (2008): 035040. http://dx.doi.org/10.1088/0960-1317/18/3/035040.

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21

Hyodo, Takeo, Kazunori Nagae, Taro Ueda, Takahiko Sasahara, and Yasuhiro Shimizu. "Sensing Behavior of Adsorption/Combustion-type Gas Microsensors to Various Alcoholic Vapors." Sensors and Materials 35, no. 11 (2023): 3851. http://dx.doi.org/10.18494/sam4403.

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22

Puyol, Rafael, Sylvain Pétré, Yann Danlée, Thomas Walewyns, Laurent A. Francis, and Denis Flandre. "Design Considerations of Ultra-Low-Power Polymer Gas Microsensors Based on Noise Analysis." Proceedings 56, no. 1 (2020): 19. http://dx.doi.org/10.3390/proceedings2020056019.

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Current sensing solutions must combine an ultra-low energy consumption trend with high reliability. The challenge lies on a fine setting of the detection threshold with the assurance of a sufficient sensitivity. In this article, the uncertainty introduced on gas sensing applications by the inherent sensor noise is studied. A 1/f model of the electronic noise in polypyrrole-based ammonia (NH3) sensors is presented and used to estimate the intrinsic signal-to-noise ratio (SNR), giving an effective precision of 10.7 bits, i.e., down to 31.4 ppb in terms of NH3 concentration. No significant improvement in SNR is achieved by increasing the bias voltage and hence the power consumption.

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23

Bolotov, V. V., P. M. Korusenko, S. N. Nesov, et al. "Fabrication of por-Si/SnO x nanocomposite layers for gas microsensors and nanosensors." Semiconductors 45, no. 5 (2011): 693–98. http://dx.doi.org/10.1134/s1063782611050071.

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24

Hagleitner, C., D. Lange, A. Hierlemann, O. Brand, and H. Baltes. "CMOS single-chip gas detection system comprising capacitive, calorimetric and mass-sensitive microsensors." IEEE Journal of Solid-State Circuits 37, no. 12 (2002): 1867–78. http://dx.doi.org/10.1109/jssc.2002.804359.

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25

Hotový, Ivan, Ivan Kostič, Štefan HAščík, Vlastimil ŘEháček, Jozef Liday, and Helmut Sitter. "Development and Fabrication of TiO2 Tip Arrays for Gas Sensing." Journal of Electrical Engineering 62, no. 6 (2011): 363–66. http://dx.doi.org/10.2478/v10187-011-0058-3.

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Development and Fabrication of TiO2Tip Arrays for Gas SensingTitanium oxide thin films were deposited at room temperature by reactive magnetron sputtering in a mixture of oxygen and argon on oxidized silicon substrates. The optimal etching characteristics of TiO2films by reactive ion etching (RIE) and RIE with inductively coupled plasma source (ICP) were investigated. Patterning of TiO2tip arrays by electron beam lithography and dry etching were developed. Different spot sizes 200 and 500 nm in diameter and with spacing 500 and 1000 nm were investigated with regards to the minimal size and the pyramidal shape. Experimental results have shown that the exposure dose optimization wa a significant parameter for controlling the tip size and its shape. We successfully fabricated the pyramidal TiO2tip arrays over an 1 × 1 mm2area. The TiO2tip array can be expected to have an important application in gas microsensors.

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26

Tomić, Milena, Milena Šetka, Ondřej Chmela, et al. "Cerium Oxide-Tungsten Oxide Core-Shell Nanowire-Based Microsensors Sensitive to Acetone." Biosensors 8, no. 4 (2018): 116. http://dx.doi.org/10.3390/bios8040116.

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Gas sensitive cerium oxide-tungsten oxide core-shell nanowires are synthesized and integrated directly into micromachined platforms via aerosol assisted chemical vapor deposition. Tests to various volatile organic compounds (acetone, ethanol, and toluene) involved in early disease diagnosis demonstrate enhanced sensitivity to acetone for the core-shell structures in contrast to the non-modified materials (i.e., only tungsten oxide or cerium oxide). This is attributed to the high density of oxygen vacancy defects at the shell, as well as the formation of heterojunctions at the core-shell interface, which provide the modified nanowires with ‘extra’ chemical and electronic sensitization as compared to the non-modified materials.

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27

Khononzon, G., and O. Rutenberg. "Microsensors and actuators based on single-crystal silicon in miniature gas chromatographs and analysers." Journal of Micromechanics and Microengineering 2, no. 4 (1992): 266–68. http://dx.doi.org/10.1088/0960-1317/2/4/009.

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28

Xue, Mianqi, Yang Zhang, Yanlian Yang, and Tingbing Cao. "Processing Matters: In situ Fabrication of Conducting Polymer Microsensors Enables Ultralow-Limit Gas Detection." Advanced Materials 20, no. 11 (2008): 2145–50. http://dx.doi.org/10.1002/adma.200702864.

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29

Xie, Zhuang, Liting Duan, Yuqian Jiang, Mianqi Xue, Meining Zhang, and Tingbing Cao. "Thinner is Better: An Ultrathin Conducting Oligoaniline Film for Gas Microsensors with Ultralow Detection Limits." Macromolecular Rapid Communications 30, no. 18 (2009): 1589–93. http://dx.doi.org/10.1002/marc.200900240.

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30

Semmache, B., S. Kallel, H. El Omari, M. Lemiti, and A. Laugier. "Dépôt chimique en phase vapeur et à basse pression de couches minces à base de silicium dans un réacteur à lampes halogène." Canadian Journal of Physics 77, no. 9 (2000): 737–43. http://dx.doi.org/10.1139/p99-035.

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Low-pressure chemical vapor deposition (LPCVD) in halogen lamp-heated reactor (RTLPCVD: rapid thermal LPCVD) is a promising technique for silicon-based thin films deposition. Indeed, overall process time and gas consumption reduction in RTP reactors allows to project new device fabrication technologies (microsensors, solar cells) in order to reach a higher environmental safety with respect to classical technologies.Various gases available on our RTP installation (SiH4, NH3, N2O, O2, PH3, B2H6) enable several silicon-based thin films RTLPCVD deposition: intrinsic polycrystalline silicon (poly-Si) films or in situ doped poly-Si, silicon nitride (Si-N) and oxynitride (Si-O-N). In this paper, we discuss our results on deposition kinetics and physical properties of these thin films. It appeared that RTLPCVD silicon-based thin films with interesting structural, electrical, and optical properties can be synthesized in our lamp-heated reactor with a tight control of process parameters such as temperature, pressure, and gas flow ratios.

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31

Villaverde, S., R. Mirpuri, Z. Lewandowski, and W. L. Jones. "Study of toluene degradation kinetics in a flat plate vapor phase bioreactor using oxygen microsensors." Water Science and Technology 36, no. 1 (1997): 77–84. http://dx.doi.org/10.2166/wst.1997.0017.

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The paper describes the toluene degradation process in a flat plate vapor phase bioreactor (VPBR) by a Pseudomonas putida 54G biofilm. Oxygen microelectrodes were used to measure oxygen concentration profiles through the gas, liquid, and biofilm phases. The linear shape of the dissolved oxygen concentration profile in the outer 87% of the biofilm thickness suggested an absence of reaction in this layer. Oxygen consumption in the remaining basal 13 % (0.3 mm) followed zero order kinetics with a rate constant of 102.2 g m−3 h−1, for toluene gas concentration of 1.5 g m−3. The increase in respiratory activity near the substratum was confirmed by microscopic study of cryogenic biofilm sections, and the lack of activity in the surface film was interpreted as a consequence of injury exerted by the toxic substrate. The accumulation of dead cells on the top of the biofilm contributed a resistance to the transport of substrates to deeper layers of the biofilm suggesting a protective role of the outer layer against the harmful effect of the toxic. These results highlight a new conceptual biofilm model in which both microbial growth and inactivation are controlled by substrate transport, leading to a structure that itself controls substrate availability.

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32

Rohe, Lena, Bernd Apelt, Hans-Jörg Vogel, Reinhard Well, Gi-Mick Wu, and Steffen Schlüter. "Denitrification in soil as a function of oxygen availability at the microscale." Biogeosciences 18, no. 3 (2021): 1185–201. http://dx.doi.org/10.5194/bg-18-1185-2021.

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Abstract. The prediction of nitrous oxide (N2O) and of dinitrogen (N2) emissions formed by biotic denitrification in soil is notoriously difficult due to challenges in capturing co-occurring processes at microscopic scales. N2O production and reduction depend on the spatial extent of anoxic conditions in soil, which in turn are a function of oxygen (O2) supply through diffusion and O2 demand by respiration in the presence of an alternative electron acceptor (e.g. nitrate). This study aimed to explore controlling factors of complete denitrification in terms of N2O and (N2O + N2) fluxes in repacked soils by taking micro-environmental conditions directly into account. This was achieved by measuring microscale oxygen saturation and estimating the anaerobic soil volume fraction (ansvf) based on internal air distribution measured with X-ray computed tomography (X-ray CT). O2 supply and demand were explored systemically in a full factorial design with soil organic matter (SOM; 1.2 % and 4.5 %), aggregate size (2–4 and 4–8 mm), and water saturation (70 %, 83 %, and 95 % water-holding capacity, WHC) as factors. CO2 and N2O emissions were monitored with gas chromatography. The 15N gas flux method was used to estimate the N2O reduction to N2. N gas emissions could only be predicted well when explanatory variables for O2 demand and O2 supply were considered jointly. Combining CO2 emission and ansvf as proxies for O2 demand and supply resulted in 83 % explained variability in (N2O + N2) emissions and together with the denitrification product ratio [N2O / (N2O + N2)] (pr) 81 % in N2O emissions. O2 concentration measured by microsensors was a poor predictor due to the variability in O2 over small distances combined with the small measurement volume of the microsensors. The substitution of predictors by independent, readily available proxies for O2 demand (SOM) and O2 supply (diffusivity) reduced the predictive power considerably (60 % and 66 % for N2O and (N2O+N2) fluxes, respectively). The new approach of using X-ray CT imaging analysis to directly quantify soil structure in terms of ansvf in combination with N2O and (N2O + N2) flux measurements opens up new perspectives to estimate complete denitrification in soil. This will also contribute to improving N2O flux models and can help to develop mitigation strategies for N2O fluxes and improve N use efficiency.

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33

Miyachi, Yoshia, Hajime Furuichi, Toshiyuki Sanada, and Yuki Mizushima. "Multipoint gas–liquid phase detection method based on a thin-film optical waveguide." Review of Scientific Instruments 93, no. 6 (2022): 065107. http://dx.doi.org/10.1063/5.0075435.

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Gas–liquid phase detection is an important technique applied in a wide range of industries. In this study, we developed a phase detection method using a film-based optical waveguide. The optical waveguide is a thin and flexible film with multi-light paths that uses multi-microsensors for gas–liquid phase detection. The intensity of the reflected light generated by different refractive indices between gas and liquid aids in distinguishing the phase. Additionally, the sensing principle is identical to that of the typical optical fiber probing technique. In this study, we investigated the detection process considering the impact of a single droplet on waveguide sensors. Furthermore, we analyzed a droplet evaporation phenomenon and a thin-film liquid flow accompanied by a high-speed airflow on the sensors. Based on the obtained results, we determined that the proposed method can effectively measure the simultaneous local multipoint and high temporal resolution phase detection on a smooth surface. Therefore, we believe that our original sensor can diagnose such a dispersed two-phase flow near the wall inside of machines or curved tubes where the high-speed visualization is hard to be applied.

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34

Catandi, Giovana D., Yusra M. Obeidat, Corey D. Broeckling, Thomas W. Chen, Adam J. Chicco, and Elaine M. Carnevale. "Equine maternal aging affects oocyte lipid content, metabolic function and developmental potential." Reproduction 161, no. 4 (2021): 399–409. http://dx.doi.org/10.1530/rep-20-0494.

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Advanced maternal age is associated with a decline in fertility and oocyte quality. We used novel metabolic microsensors to assess effects of mare age on single oocyte and embryo metabolic function, which has not yet been similarly investigated in mammalian species. We hypothesized that equine maternal aging affects the metabolic function of oocytes and in vitro-produced early embryos, oocyte mitochondrial DNA (mtDNA) copy number, and relative abundance of metabolites involved in energy metabolism in oocytes and cumulus cells. Samples were collected from preovulatory follicles from young (≤14 years) and old (≥20 years) mares. Relative abundance of metabolites in metaphase II oocytes (MII) and their respective cumulus cells, detected by liquid and gas chromatography coupled to mass spectrometry, revealed that free fatty acids were less abundant in oocytes and more abundant in cumulus cells from old vs young mares. Quantification of aerobic and anaerobic metabolism, respectively measured as oxygen consumption rate (OCR) and extracellular acidification rate (ECAR) in a microchamber containing oxygen and pH microsensors, demonstrated reduced metabolic function and capacity in oocytes and day-2 embryos originating from oocytes of old when compared to young mares. In mature oocytes, mtDNA was quantified by real-time PCR and was not different between the age groups and not indicative of mitochondrial function. Significantly more sperm-injected oocytes from young than old mares resulted in blastocysts. Our results demonstrate a decline in oocyte and embryo metabolic activity that potentially contributes to the impaired developmental competence and fertility in aged females.

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35

Lauque, P. "Sputtered thin films of CuBr as electrochemical microsensors for NH3 gas: structure, sensitivity and aging effects." Solid State Ionics 136-137, no. 1-2 (2000): 603–6. http://dx.doi.org/10.1016/s0167-2738(00)00343-x.

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36

ZOHAR, YITSHAK, SYLVANUS YUK KWAN LEE, WING YIN LEE, LINAN JIANG, and PIN TONG. "Subsonic gas flow in a straight and uniform microchannel." Journal of Fluid Mechanics 472 (November 30, 2002): 125–51. http://dx.doi.org/10.1017/s0022112002002203.

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A nonlinear equation based on the hydrodynamic equations is solved analytically using perturbation expansions to calculate the flow field of a steady isothermal, compressible and laminar gas flow in either a circular or a planar microchannel. The solution takes into account slip-flow effects explicitly by utilizing the classical velocity-slip boundary condition, assuming the gas properties are known. Consistent expansions provide not only the cross-stream but also the streamwise evolution of the various flow parameters of interest, such as pressure, density and Mach number. The slip-flow effect enters the solution explicitly as a zero-order correction comparable to, though smaller than, the compressible effect. The theoretical calculations are verified in an experimental study of pressure-driven gas flow in a long microchannel of sub-micron height. Standard micromachining techniques were utilized to fabricate the microchannel, with integral pressure microsensors based on the piezoresistivity principle of operation. The integrated microsystem allows accurate measurements of mass flow rates and pressure distributions along the microchannel. Nitrogen, helium and argon were used as the working fluids forced through the microchannel. The experimental results support the theoretical calculations in finding that acceleration and non-parabolic velocity profile effects were found to be negligible. A detailed error analysis is also carried out in an attempt to expose the challenges in conducting accurate measurements in microsystems.

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Gunasekaran, Vignesh, Soffian Yjjou, Eve Hennequin, et al. "A New Miniaturized Gas Sensor Based on Zener Diode Network Covered by Metal Oxide." Micromachines 12, no. 11 (2021): 1355. http://dx.doi.org/10.3390/mi12111355.

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The development of “portable, low cost and low consumption” gas microsensors is one of the strong needs for embedded portable devices in many fields such as public domain. In this paper, a new approach is presented on making, on the same chip, a network of head-to-tail facing PN junctions in order to miniaturize the sensor network and considerably reduce the required power for heating each cell independently. This paper is about recognizing a device that integrates both sensing and self-heating. This first study aims to evaluate the possibilities of this type of diode network for use as a gas sensor. The first part concerns the description of the technological process that is based on a doped polysilicon wafer in which a thin layer of metal oxide (a gallium-doped zinc oxide in our case) is deposited by RF sputtering. An electrical model will be proposed to explain the operation and advantage of this approach. We will show the two types of tests that have been carried out (static and dynamic) as well as the first encouraging results of these electrical characterizations under variable atmospheres.

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Shaalan, N. M., T. Yamazaki, and T. Kikuta. "Effect of micro-electrode geometry on NO2 gas-sensing characteristics of one-dimensional tin dioxide nanostructure microsensors." Sensors and Actuators B: Chemical 156, no. 2 (2011): 784–90. http://dx.doi.org/10.1016/j.snb.2011.02.039.

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39

Archanjo, Bráulio S., Pablo F. Siles, Camilla K. B. Q. M. Oliveira, Daniel L. Baptista, and Bernardo R. A. Neves. "Characterization of Metal Oxide-Based Gas Nanosensors and Microsensors Fabricated via Local Anodic Oxidation Using Atomic Force Microscopy." Advances in Materials Science and Engineering 2013 (2013): 1–13. http://dx.doi.org/10.1155/2013/898565.

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This work reports on nanoscale and microscale metal oxide gas sensors, consisting of metal-semiconductor-metal barriers designed via scanning probe microscopy. Two distinct metal oxides, molybdenum and titanium oxides, were tested at different temperatures using CO2and H2as test gases. Sensitivities down to ppm levels are demonstrated, and the influence of dry and humid working atmospheres on these metal oxide conductivities was studied. Furthermore, the activation energy was evaluated and analyzed within working sensor temperature range. Finally, full morphological, chemical, and structural analyses of the oxides composites are provided allowing their identification as MoO3and Ti.

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Tamaki, Jun, Jun Niimi, Shunsuke Ogura, and Satoshi Konishi. "Effect of micro-gap electrode on sensing properties to dilute chlorine gas of indium oxide thin film microsensors." Sensors and Actuators B: Chemical 117, no. 2 (2006): 353–58. http://dx.doi.org/10.1016/j.snb.2005.11.005.

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41

Seleznev, V. A., V. Ya Prinz, V. M. Aniskin, and A. A. Maslov. "Generation and registration of disturbances in a gas flow. 1. Formation of arrays of tubular microheaters and microsensors." Journal of Applied Mechanics and Technical Physics 50, no. 2 (2009): 291–96. http://dx.doi.org/10.1007/s10808-009-0039-5.

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42

Shiplyuk, A. N., V. M. Aniskin, V. A. Seleznev, V. Ya Prinz, A. A. Maslov, and R. S. Matvienko. "Generation and registration of disturbances in a gas flow. 2. Experiments with arrays of tubular microheaters and microsensors." Journal of Applied Mechanics and Technical Physics 50, no. 3 (2009): 454–58. http://dx.doi.org/10.1007/s10808-009-0060-8.

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43

Wilén, B. M., D. Gapes, L. L. Blackall, and J. Keller. "Structure and microbial composition of nitrifying microbial aggregates and their relation to internal mass transfer effects." Water Science and Technology 50, no. 10 (2004): 213–20. http://dx.doi.org/10.2166/wst.2004.0647.

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This paper presents an analysis of the structure and microbial composition of nitrifying aggregates, formed as either flocs or granules, in sequencing batch reactors (SBR) operated with a high ammonium load. The structure and microbial community of the aggregates was determined by fluorescence in situ hybridisation (FISH). The aggregate structure and size was related to mass transfer limitations observed by measurements of OURs measured by either a titrimetric and off-gas analysis sensor (TOGA) or by microsensors. The FISH analysis showed that the spatial arrangement of the microbial consortia correlated well with the oxygen gradients inside the aggregates. In the larger aggregates, the ammoniumand nitrite-oxidising bacteria were mainly concentrated to the outer 100–200 μm, whereas in the floc system, the bacteria were distributed throughout the entire aggregate. This indicates that the internal mass transfer resistance is considerably larger when the aggregate size increases which is directly supported by TOGA measurements.

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Dominguez, J. E., L. Fu, and X. Q. Pan. "TEM Study of the Effect of the Sapphire Substrate Surface Orientation on the Microstructure of Tin Dioxide Films." Microscopy and Microanalysis 7, S2 (2001): 1220–21. http://dx.doi.org/10.1017/s1431927600032177.

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Tin dioxide (SnO2) has been extensively studied and used as gas sensors to detect toxic gases such as CO, NOxand flammable gases like H2.[l] Recently, considerable researches have focused on thin film sensors due to their high performance as well as their integration compatibility with semiconductor technology for making microsensors and sensor arrays. [2] The performance of thin film sensors is remarkably influenced by the way they were fabricated.[3] Among various deposition techniques, pulsed laser deposition (PLD) has shown great prominence in the deposition of a wide variety of oxide thin film materials such as high Tc superconductors, semiconductors and dielectrics. in this work we present our experimental results on tin dioxide films deposited using pulsed laser ablation on sapphire (α -Al2O3) substrates with different surface orientations.Tin oxide films with a thickness of 100 nm were deposited on the (1012) and (0001) sapphire by pulsed laser ablation of ceramic SnO2 targets.

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Geiling, Thomas, Tilo Welker, Christiane Ehrling, and Jens Müller. "Design, Fabrication, and Operation of a Nitrogen Monoxide Measurement Device Based on LTCC." Journal of Microelectronics and Electronic Packaging 9, no. 4 (2012): 171–77. http://dx.doi.org/10.4071/imaps.343.

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We present a so-called micro total analytical system (μTAS) for the measurement of low nitrogen monoxide (NO) concentrations in gas flows. The measurement principle is based on the chemiluminescent reaction of NO with ozone (O3). The presented system scales down this measurement principle into the realm of microfluidics and microsensors. Low temperature cofired ceramics (LTCC) have proven to be the ideal technology for the realization of a μTAS, as they offer high chemical and thermal stability as well as high degree of freedom of design. The system consists of four components: an ozone generator, an ozone concentration measurement via UV transmission, a chemiluminescent detection (CLD) chamber, and an exhaust gas treatment. The ozone generator is a microplasma device in which ozone is produced by a dielectric barrier discharge (DBD) mechanism. From the generator, the ozone is fed into a chamber with an optical port, where the concentration is determined by UV transmission measurements. Then it is brought into contact with the NO-containing analyte gas inside the reaction chamber, where the chemiluminescent reaction occurs. The reaction chamber is outfitted with an optical port as well, so that the emitted radiation can be detected and analyzed with a photodiode. The gas mixture leaving the reaction chamber is fed through a platinum catalyst, in order to decompose leftover ozone and prevent buildup of hazardous concentrations in the surroundings of the device. This paper presents the design of each component as well as the integrated system and gives detailed measurements of its operation.

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Rodríguez, Daniel, Juan Bonaparte, Norberto Boggio, and Alejandro Fasciszewski. "Desarrollo y fabricación de un microsensor de gas de baja potencia para la detección de amoniaco a bajas concentraciones." Tecnura 23, no. 61 (2019): 23–30. http://dx.doi.org/10.14483/22487638.15353.

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Contexto: En este trabajo se presenta el desarrollo y microfabricación de un sensor de gas cuyo funcionamiento se basa en las variaciones de su conductividad eléctrica en presencia de determinados gases. Para utilizar estos sensores en equipos portátiles, como monitores de gases, se requiere que la potencia utilizada para mantener la película sensible a la temperatura de funcionamiento sea muy baja. Los resultados de este desarrollo permiten contar además con una plataforma para la microfabricación de sensores de gas, sobre la que se pueda incorporar diversos tipos de películas sensoras. Metodología: El microsensor desarrollado está constituido por una película delgada de SnO2 depositada sobre un sustrato de silicio micromaquinado. El diseño propuesto se realizó mediante simulaciones de los comportamientos mecánico y térmico. El procedimiento incluyó operaciones de microfabricación. Posteriormente se realizó la caracterización eléctrica y se ensayó la sensibilidad frente a amoniaco gaseoso. Resultados: La microfabricación se llevó a cabo de forma satisfactoria (no se detallan todos los pasos en el presente trabajo), y se logró una alta tasa de sensores bien conformados por oblea. La caracterización del sensor frente a diferentes concentraciones de amoniaco gaseoso en aire dio como resultado una respuesta lineal para concentraciones entre 6 ppm a 50 ppm , donde este último es el límite permisible de exposición . Conclusiones: Se desarrolló un proceso para fabricar un microsensor de gas de SnO2 de bajo consumo (50 mW). Se llevó a cabo la fabricación de los microsensores de manera satisfactoria, partiendo de simulaciones previas. En relación a trabajos futuros, la plataforma micromaquinada desarrollada, con el calefactor incorporado, permitirá utilizar distintas películas sensoras.

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Stolle, Christian, Mariana Ribas-Ribas, Thomas H. Badewien, et al. "The MILAN Campaign: Studying Diel Light Effects on the Air–Sea Interface." Bulletin of the American Meteorological Society 101, no. 2 (2020): E146—E166. http://dx.doi.org/10.1175/bams-d-17-0329.1.

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Abstract The sea surface microlayer (SML) at the air–sea interface is &lt;1 mm thick, but it is physically, chemically, and biologically distinct from the underlying water and the atmosphere above. Wind-driven turbulence and solar radiation are important drivers of SML physical and biogeochemical properties. Given that the SML is involved in all air–sea exchanges of mass and energy, its response to solar radiation, especially in relation to how it regulates the air–sea exchange of climate-relevant gases and aerosols, is surprisingly poorly characterized. MILAN (Sea Surface Microlayer at Night) was an international, multidisciplinary campaign designed to specifically address this issue. In spring 2017, we deployed diverse sampling platforms (research vessels, radio-controlled catamaran, free-drifting buoy) to study full diel cycles in the coastal North Sea SML and in underlying water, and installed a land-based aerosol sampler. We also carried out concurrent ex situ experiments using several microsensors, a laboratory gas exchange tank, a solar simulator, and a sea spray simulation chamber. In this paper we outline the diversity of approaches employed and some initial results obtained during MILAN. Our observations of diel SML variability show, for example, an influence of (i) changing solar radiation on the quantity and quality of organic material and (ii) diel changes in wind intensity primarily forcing air–sea CO2 exchange. Thus, MILAN underlines the value and the need of multidiciplinary campaigns for integrating SML complexity into the context of air–sea interaction.

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Sazhin, Oleg. "Flow Microsensor of Thermal Type for Measurements of Gas Fluxes." Applied Mechanics and Materials 249-250 (December 2012): 118–25. http://dx.doi.org/10.4028/www.scientific.net/amm.249-250.118.

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An analytical model of the flow sensor of thermal type is developed. The results of the model application are used to develop a flow microsensor of thermal type with optimal functional characteristics. The technology of microsensor manufacturing is provided. The prototype of the microsensor suitable for use in the mass air flow meter is created. The basic characteristics of the microsensor are presented.

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Liang, Chen-Wei, and Chang-Hung Shen. "An integrated uncrewed aerial vehicle platform with sensing and sampling systems for the measurement of air pollutant concentrations." Atmospheric Measurement Techniques 17, no. 9 (2024): 2671–86. http://dx.doi.org/10.5194/amt-17-2671-2024.

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Abstract. In this study, an uncrewed aerial vehicle (UAV) platform with sensing and sampling systems was developed for three-dimensional (3D) measurements of air pollutant concentrations. The sensing system of this platform contains multiple microsensors and Internet of Things devices for determining the 3D distributions of four critical air pollutants and two meteorological parameters in real time. Moreover, the sampling system comprises remote-controllable gas sampling kits, each of which contains a 1 L Tedlar bag for the 3D measurement of volatile organic compound (VOC) concentrations according to the Toxic Organics-15 (TO-15) method of the US Environmental Protection Agency. The performance of the developed UAV platform was verified in experiments where it was used to detect air pollutant emissions from a large industrial zone in Taiwan that included a traditional industrial park, a precision machinery park, and a municipal waste incineration plant. Three locations were selected as field measurement sites according to the prevailing local wind direction. The vertical distributions of four critical air pollutants, the ambient temperature, and the relative humidity were determined from data gathered at the aforementioned sites in March and May 2023. A total of 56 and 72 chemical species were qualitatively and quantitatively analyzed in these two periods, respectively. The experimental results verified the feasibility of using the proposed UAV platform for accurately evaluating the air pollutant concentration distribution and transport in an industrial zone. The sampling system can be used as the sampling part of the TO-15 method, thus extending the method to measure the 3D distribution of VOCs in an area. The UAV platform can serve as a useful tool in the management of and decision-making process for air pollution in industrial areas.

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Vauchier, Claude, Daniel Charlot, Gilles Delapierre, and Antoinette Accorsi. "Thin-film gas catalytic microsensor." Sensors and Actuators B: Chemical 5, no. 1-4 (1991): 33–36. http://dx.doi.org/10.1016/0925-4005(91)80216-7.

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