IR emitting Dy3+ doped chalcogenide fibers for in situ CO2 monitoring in high pressure microsystems

This paper reports the carbon dioxide detection in silicon-Pyrex high pressure microfluidic devices mimicking geological conditions encountered in deep saline aquifers using an in situ infrared optical sensor. The middle infrared source inserted inside the microchannel is based on infrared emission from Dy3+ sulfide glass fibers. The broad emission of the Dy3+ doping in infrared fibers is used to directly probe the CO2 thanks to the perfect overlap between the rare earth emission centered at 4.4 μm and the CO2 absorption band located at 4.3 μm. CO2 and water were clearly distinguished when using segmented flow on chip at pressures ranging from 4.5 to 6 MPa. These results demonstrate the feasibility of the infrared optical detection of other gases displaying absorption bands in the middle infrared domain for further developments of gas sensors, which can find applications in geological media monitoring and microfluidics.Micro-laboratoires géologiques sur puce pour l'étude des processus clés du transport réactif multiphasique appliqués au stockage géologique du CO2