Utilisation des microcontroleurs et des capteurs pour la surveillance environnementale : Application à la détection des rayonnements ionisants et de certains polluants atmosphériques

Abstract

This thesis focuses on the design and development of portable and intelligent low-cost devices dedicated to the real-time monitoring of atmospheric pollutants and ionizing radiation. Two types of devices based on microcontroller cards, gas sensors or Geiger-Müller tube detectors have been realized, namely a survey meter and two devices for measuring toxic gases (one for atmospheric pollutants and the other for air quality assessment). The survey meter detects the ambient dose rate of ionizing radiation while the air quality devices measure particulate matter (PM2:5), toxic gases (O3, CO, SO2, NO2, CO2, smoke, liquefied petroleum gas, etc.) and atmospheric parameters such as temperature (T) and humidity (H). These devices incorporate electronic components such as the GPRS card and the XBee modules of ZigBee technology that allow the Internet of Things (IoT) functionality to be established with a remote computer or an operator via the mobile phone. A comparative analysis of the particles matter concentrations (PM2:5) obtained from the prototype for measuring atmospheric pollutants and a conventional method based on the "Gent Sampler" (reference method) is carried out by placing both devices at the same sampling site to collect data for two months. The linear regression of the data obtained made it possible to highlight a good agreement between the two methods with a correlation coefficient of 0:8897. In addition, a reliability coefficient of 1:00 obtained from this analysis confirms the effectiveness of the realized pollutant measurement device. Another comparative analysis of data from the survey meter developed and that of a reference method (the Gamma RAD5) was carried out. The two devices are used in the same place at different times using the GPS coordinates. This analysis gave an average value of 64:30nGy=h of the data from the realized survey meter, compared to 50:67nGy=h obtained by the RAD5 gamma spectrometer. Moreover, beyond the aforementioned precision, the realized devices are portable and have a low production cost (200 to 350 thousand FCFA per device), they operate in real time and consume less energy (1.7 to 6.68 Watt) compared to the reference devices used (1.5 and 352 Watt). They measure several pollutants and generate a large amount of data in a very short time (a few minutes). They are an alternative local solution to the commercial offer.