New applications of tin oxide gas sensors - I. Molecular identification bycyclic variation of the working temperature and numerical analysis of the signals
H. Kohler et al., New applications of tin oxide gas sensors - I. Molecular identification bycyclic variation of the working temperature and numerical analysis of the signals, SENS ACTU-B, 61(1-3), 1999, pp. 163-169
The molecular identification capabilities of commercial tin oxide semicondu
ctor gas sensor elements (TGS 823, Figaro, Japan) are considerably enhanced
by a special operation procedure. Only one gas sensor, operated in a 4-min
cycle between 70 degrees C and 300 degrees C is used to determine the type
of substance and its concentration. This is achieved by the numerical anal
ysis of conductivity-time profiles recorded periodically and simultaneously
during cyclic variation of the working temperature. A concept of a compara
tively economic procedure for calibration and analysis was developed and is
discussed in the light of the special properties of the sensor elements. S
ensor test results employing the sensor element in an immersion probe behin
d a gas permeable membrane for identification and quantitative determinatio
n of volatile organic solvents in water are presented exemplary for the fiv
e-component system ethanol, toluene, benzene, acetone and ethylacetate. (C)
1999 Elsevier Science S.A. All rights reserved.