Organic vapors sensing

Goubaidoulline, L, Vidrich, G., and Johannsmann, D., Organic vapor sensing with ionic liquids entrapped in alumina nanopores on quartz crystal resonators. Anal. Chem., 77,615-619,2005. 

Organic Vapor-Sensing Characteristics of PEDOT-PSS/PVP and PVP Nanofibers... 

Fig.3 Schematic diagram of experimental-setup for volatile organic vapor sensing technique based electrical properties...

R., Gelperin, A., Katz, H. E. and Bao, Z. (2001) Organic oscillator and adaptive amplifier circuits for chemical vapor sensing./. Appl. Phys., 91, 10140. 

Soils with greater amounts of organic matter (agricultural or forest soils) or minerals (compared to desert sand) will sorb greater landmine signature chemicals,6 leaving less available for transfer to the air for vapor sensing. 

Liang, C., Yuan, C.Y, Warmack, R.J., Barnes, C.E., and Dai, S., Ionic liquids A new class of sensing materials for detection of organic vapors based on the use of a quartz crystal microbalance. Anal. Chem., 74,2172-2176, 2002. 

Abstract Cataluminescence (CTL) is chemiluminescence emitted in a course of catalytic oxidation. Since 1990, the present authors and coworkers have observed CTL during the catalytic oxidation of various organic vapors in air. This phenomenon has been applied to the CTL-based sensors for detecting combustible vapors. THE CTL response is fast, reproductible and proportional to the concentration of the combustible vapors of ppm orders in air. Based on two types of models of the CTL, the relationship between the CTL intensity and the rate of catalytic oxidation have been investigated analytically. In this article, the effects of catalyst temperature, gas flow-rate and gas concentration on the CTL intensity are demonstrated. Finally, various types of sensing system using the CTL-based sensor are proposed. The results of discrimination and determination of more than ten types of vapors of various concentrations are shown. 

Katz, and Z. Bao, Organic oscillator and adaptive amplifier circuits for chemical vapor sensing , Journal... 

Conductive polymers such as polypyrrole or polyaniline have been applied to sensing vapor and gases. These sensors change their conductivity when exposed to organic vapors because of the effects the vapors have on the availability of charge carriers. One way to obtain selectivity for these materials is... 

Teleki, A., Pratsinis, S. E., Kalyanasundaram, K. and Gouma, P. I. (2006). Sensing of organic vapors by flame-made Ti02 nanoparticles. Sens. Actuator B-Chem. 119(2), 683-690. 

Organic Vapor-sorbing sensing materials Vapor partition coefficients between air and sensing materials 44... 

When an organic vapor, such as methane, in low pressure (e.g., less than 1 torr) is subjected to an electromagnetic field, the electrical breakdown of the gas occurs, yielding a glow the color of which is characteristic to the gas. In the luminous gas phase, methane is activated and forms a polymeric deposition in the form of a coating on the surface of substrate placed in the glow. This process is termed plasma polymerization because the luminous gas phase or glow indicates the presence of plasma, and the process does not proceed without plasma. The strict definition of plasma is (at least partially) ionized gas, which maintains the electrical neutrality as a whole. The luminous gas phase in which plasma polymerization takes place, however, is not plasma in the strict sense. 

Mukhopadhyay et al. first used LB films of specially substituted phthalocyanine molecules to sense toluene vapor based on the changes in the electrical conductivity [9]. Phthalocyanine and porphyrin derivatives are p-type semiconductors. The interaction with n-electron systems can lead to a cofacial orientation of the nucleus, resulting in a one-dimensional semiconducting system. The exposure to the VOCs may change the cofacial molecular orientation and, as a consequence, the conductivity. However, the interaction between the VOCs and the sensitive molecules is not very strong, as these VOCs are not strong electron donors or electron acceptors. A very low conductivity of 10 to 10 S/cm was usually measured when the sensitive layers were exposed to the VOCs, which is difficult to be detected. Therefore, in most cases, the mass transduction and UV-vis absorption method were adopted to detect the presence of organic vapors. 

Kim, H., Kim, Y. and Lee K. Sensing characteristics of the organic vapors according to the reflectance spectrum in the porous silicon multilayer structure , (2011) Sensor. Actual A. 165,276-9. 

A. Quaranta, S. Carturan, M. Bonafini, G. Maggioni, M. Tonezzer, G. Mattel, C. de Julian Fernandez, G. Della Mea, and P. Mazzoldi. Optical sensing to organic vapors of fluorinated polyinfide nanocomposites containing silver nanoclusters. Sens. Actuators, B, 118(l-2) 418-424, October 2006. 

The sensing behaviors of PEDOT-PSS/PVP (Fig. 5.21) and PVP nanofibers on ethanol, methanol, THF, and acetone vapors are studied. The sensing was carried out for several q cles by repeated exposure of the nanofibers to saturated organic vapors and air alternately. Both PEDOT-PSS/PVP and PVP electrospun nanofiber sensors have exhibited good reversibility, reproducibility and response and recovery time. The response and recovery time of PEDOT-PSS/PVP nanofibers upon exposure to ethanol vapor are much faster than those of PVP nanofibers. 

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