Sensors organic vapors

Laguna, M., Bariain, C., Garrido, J., Mafias, l.R. and Romeo, 1. (2001) Optical fiber sensor for volatile organic vapors. Patent WO-047936. 

Taguchi-type semiconductor sensors doped with various catalysts were used to form the array. Combustion of organic vapors takes place at the surface of the sensors and this reaction is influenced by the type and amount of various catalysts. Traditionally, these sensors are operated under steady-state conditions of the vapor flowing past the array. The steady-state sensor intensity reflects the amount of combustion. In this study, the sensors are used in a... 

B. M. Cordero, and M. Forina, Electronic Nose Based on Metal Oxide Semiconductor Sensors as a Fast Alternative for the Detection of Adulteration of Virgin Olive Oils, Anal. Chim. Acta 2002,459, 219 C. L. Honeyboume, Organic Vapor Sensors for Food Quality Assessment, J. Chem. Ed. 2000, 77, 338 E. Zubritsky, E-Noses Keep an Eye on the Future. Anal. Chem. 2000, 72. 

Table 8.1 Response of commercial SnC>2 sensor to organic vapors in air...

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. 

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... 

Shang et al. 2009 (61) MWCNT Purified Microemulsion polymerization CNT Loading levels 1 tol5wt% MWCNT-PMMA composites prepared by microemulsion polymerization at 8 wt% loading showed high sensor responses to different organic vapors such as acetone, toluene, THF, choloroform, acetonitrile, benzene They suggested the use of these composites for gas sensor applications ... 

The detection performance of the molecular sieve coated sensor is examined from the measurement of frequency variation while different concentrations of organic vapor contained air are contacted to the sensor sur e. While organic vapor contained air flows continuously with constant flow rate of 0.4 IVmin., the variation of frequency is monitored and the outcome is converted to the organic concentration. In order to examine the process of adsorption and desorption of the organic vapor on the molecular sieve coated on the sensor surface, fresh air and organic substance contained air are alternately provided. 

Figure 5 shows the relation between methanol concentration and frequency shift with 5 A molecular sieve coated sensor. Hus indicates the measured frequency shift gives the concentration of organic vapor. 

Honeybourne, C. L., Organic vapor sensors for food quality assessment, J. Chem. Educ. 2000, 77, 338-344... 

Svetiidc, V. Schmidt, A. J. Miller, L. L., Conductometric sensors based on the hypersensitive response of plasticized polyaniline films to organic vapors, Chem. Mater. 1998,10,3305-3307... 

Nakagawa, M. Okabayashi, T. Fujimoto, T. Utsunomiya, K Yamamoto, I. Wada, T. Yamashita, Y. Yamashita, N., A new method for recognizing organic vapor by spectroscopic image on cataluminescence-based gas sensor, Sens. Actuators B 1998, 51, 159-162... 

Gong, H. Wang, Y. J. Teo, S. C. Huang, L., Interaction between thin-film tin oxide gas sensor and five organic vapors, Sens. Actuators B 1999, 54, 232-235... 

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