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Développement de systèmes multicapteurs et multivariables pour la mesure en continu de polluants atmosphériques

Abstract : The purpose of this work was to measure the concentrations of atmospheric pollutants using sensors based on a metal semiconductor, tin dioxide. These sensors were tested with two reducing gases which are carbon monoxide (0-20 ppm), a mixture of hydrocarbons (0-10 ppm) and two oxidizing gases which is ozone (0-500 ppb) and nitrogen dioxide (0-500 ppb). One of the major disadvantages of this type of sensor is their lack of selectivity. Thus the association of several different sensors in multisensors system can be a solution.
We have developed an automated test bench able to generate the suitable gas concentrations with a controlled humidity. It is then possible to carry out the acquisition of four devices (mono or multisensors) with cycles of temperature.
We followed the evolution with their age of the performances of various sensors worked out by serigraphy. At the end of these experiments, we showed the interest of the use of some of these sensors for the evaluation of two major components of pollution: ozone and hydrocarbons. We could not prove that the capacitive effects and the effects of electrode were useful parameters for our application. Nevertheless, the measurement with increasing temperature give additional information.
Thus, two multisensors systems were carried out. One associates three independent sensors and the other consists of three layers deposited on the same heating substrate. These three layers are initially identical (tin dioxide) but two are covered with a thin film, platinum for one and silica for the other. Moreover, one system made up of three commercial sensors used with a constant temperature was also tested. For each studied system, we built behavior models using a Neural Network algorithm. Whereas the models carried out using synthetic gas mixtures appeared unusable for measurements in real pollution, it was shown that a model calibrated directly with air bled in urban environment appears effective for the measurement of hydrocarbon and the ozone concentrations. The portability of these models between various identical multisensors was proven, but their lifespan was limited to ten days.
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Submitted on : Tuesday, September 20, 2005 - 3:26:17 PM
Last modification on : Wednesday, June 24, 2020 - 4:18:31 PM
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  • HAL Id : tel-00010218, version 1

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Marc Kamionka. Développement de systèmes multicapteurs et multivariables pour la mesure en continu de polluants atmosphériques. Matériaux. Ecole Nationale Supérieure des Mines de Saint-Etienne, 2005. Français. ⟨tel-00010218⟩

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