PhD Student
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PhD Topic : Manufacture of microsystems for colorimetric detection of toxic gases
Toxic gases are increasingly present in our environment as a result of combustion phenomena, materials or liquid compounds during manufacture or use, or fermentation processes. These gases are often present in significant quantities in enclosed domestic areas, industrial areas, agricultural areas and along major roads.
Above a certain threshold, they can pose a threat to exposed people and the environment. It is therefore necessary to qualify and quantify airborne toxic substances using sensors. Numerous detection methods exist, the most common being electrochemical or CMOS sensors, but this thesis project is in the field of colorimetric chemical sensors.
The objectives of this thesis are to improve the fabrication of a colorimetric detection microsystem, to evaluate its suitability for the detection of toxic substances in the gas phase, and to gain a better understanding of the phenomena that occur in these microsystems in a confined environment.
At the heart of the project was the development of miniaturized porous materials doped with molecules capable of inducing a color change through interaction with the target compound. These materials, obtained using microfluidic technology, were fabricated in the form of microsystems containing about a hundred colorimetric beads per cm². Our work has improved the robustness of the process by modifying parameters related to chemical reactivity and fluid circulation.
Exposures were performed to demonstrate the ability of the sensor obtained from these microsystems to detect toxic gases such as formaldehyde and ammonia. The microsystems were exposed to the toxic gases in different ways, and the resulting color changes were measured and analyzed.
Finally, by studying some of the key steps that occur in the microsystem, such as gelation, we have improved our understanding of the fabrication process and the limited reactions in the microsystem in relation to the sol-gel process, the microsystem, and detection.