Une nouvelle méthode d’introduction de phases stationnaires solides dans des micro colonnes de silicium a été proposée. L’utilisation de la pulvérisation cathodique comme méthode de dépôt de phase stationnaires comme la silice, l’alumine, le graphite ou la magnésie, répond à la fois aux critères de procédé d’insertion collectif et de technique industrialisable et intégrable dans une ligne de micro usinage du silicium en salle blanche conventionnelle.
Les propriétés chromatographiques de ces colonnes en termes de séparations rapides et efficaces d’hydrocarbures volatils, et d’adaptabilité à diverses exigences du terrain, en font une technologie prometteuse dans le cadre de la miniaturisation de la chromatographie en phase gazeuse pour des analyses rapides sur site, en temps réel, et éventuellement autonomes.
Bien que des études complémentaires concernant la précision de la méthode employée (fabrication, robustesse en mode cycles thermiques) doivent être menées, l’intérêt des communautés scientifiques et industrielles pour cette découverte a été démontré à plusieurs reprises par des publications et communications d’une part, et des brevets et leur application au XXXXXXXXXXX dans le but d’un déploiement industriel à court terme d’autre part.
A plus long terme, des études plus détaillées sur le sujet pourraient par exemple porter sur d’autres matériaux pulvérisables, ou sur la comparaison avec de la pulvérisation réactive; des développements pour d’autres applications, comme la surveillance de composés organiques volatils, devraient être envisagés.
Mots clés : micro chromatographie en phase gazeuse, pulvérisation cathodique, MEMS, hydrocarbures, alcanes, silice, alumine, graphite, magnésie, séparations rapides.
Acknowledgements
First and foremost, I wish to thank any reader of this report. Thank you for your time and consideration, I hope you had a pleasant and enriching reading.
My second thanks are dearly expressed to my PhD thesis director Jérôme Vial, who always behaved towards me not only with honesty, transparency and scientific rigor, but also with a positive, trustful, and enthusiastic state of mind. It was a most pleasant experience to work under his supervision. In a similar manner, grateful thanks are expressed to my co-director Didier Thiébaut, for similar reasons. Assistance provided by Zineb Matouk during her 6 months master internship was greatly appreciated, as well as her tireless and joyful motivation, including through harsh technical difficulties. Still within the ESPCI, sincere and special thanks are due to Imadeddine Azzouz and Fabien Brothier, for being two of my PhD fellows, to Patrick Sassiat, for technical advising and support, to Wassim Hadj Ali, for teaching me supervising practical works, to Joachim Fleury for representing the unfolding of the LSABM – GeoServices collaboration, and to the whole department staff, from the interns and service agents to the director, through PhD students and permanent members. Many things changed at Schlumberger MEMS TC between my arrival in March 2010 and my defense in February 2014, but obviously nothing was forgotten. My first thanks are sincerely expressed to my former supervisor Bertrand Bourlon: in spite of occasional disagreements, I learned a lot from him and I am most thankful to him for providing tangible industrial credit to the discovery by finding a direct and practical application of the discovery, and establishing a collaboration with GeoServices. From those early days, acknowledgements are as well due to Eric Donzier, Bernard Montaron, Joyce Wong and Pierre Guibal, without whom the project would not have been possible as well. From the latter days, I wish to acknowledge the assistance of Emna Zoghlami (6 month master intern) for providing significant results and perfecting my supervising skills, the technical help of Sébastien Prangère and Alain Hohn, and the availability, generosity, and wise advices of MEMS TC manager Patrice Ligneul. And last, but not least, I wish to mention the pleasure to share all these moments with my fellows, Kamran Danaie, Maxime Projetti, Thomas Raillot and Florian Risser, and with all the other people at MEMS TC.
My special thanks are naturally extended to the people involved in the project at GeoServices, firstly Jérôme Brévière (also invited examiner of this work) and Pawel Kasprzykowski, but also Reda Karoum, Patrick Banik, Vincent Châtelet, François Chevillard and Jean-Pierre Poyet, for their interest and commitment in the development of the application.
Other professional acknowledgements are deeply expressed to Frédéric Marty from the ESIEE for technical support in the early days, and to Bruno Gallas and Vincent Rouessac for very kindly accepting to operate measurements on sputter-deposited layers, and for helping understand a few key points regarding layer structure.
All the members of the thesis defense jury are mostly and gratefully thanked for their time, attention, and interest: Carlo Bicchi and Jérôme Randon (reporters), Jacques Fattacioli, Franck Launay, Michel Sablier and Jérôme Brévière (examiners), Jérôme Vial and Didier Thiébaut (directors).
My thanks are finally expressed to my friends and family, and to my dear Pauline Valois, who is coincidentally as well PhD student at Schlumberger and the ESPCI at the moment of this writing.
Abstract and keywords
A totally new solid stationary phase deposition technique for micro machined gas chromatography columns fabrication dedicated to oilfield applications was proposed: to overcome the limitations of liquid stationary phases (such as polymethylsiloxane) or occasionally reported solid stationary phases (carbon nanotubes, functionalized gold, conventional packing materials) in terms of very volatile compounds retention and/or clean room batch production, a new approach consisting of the collective direct deposition of the adsorbent in micro columns channels by sputtering was performed. The process was fully compatible with clean room fabrication flow and industry-ready, with very good (yet only partially demonstrated) precision results.
Silica, alumina, graphite and magnesia were proven able to separate volatile hydrocarbons. Various stationary phases (deposited materials and thicknesses, process pressure) and types of columns (structure, geometrical dimensions) were fabricated in the form of 2 cm x 2 cm x 1 mm silicon-Pyrex chips, and chromatographically evaluated, and their thermodynamic and kinetic properties were quantitatively reported. Retentions were qualitatively observed to increase from magnesia to graphite through alumina and silica and with phase ratio decrease, as expected; very satisfying efficiencies were obtained: more than 5700 plates for open sputter-deposited silica columns, and a plate height of 250 µm for semi-packed sputter- deposited alumina columns.
The possibility to use such columns for fast in-situ and autonomous monitoring of light hydrocarbons in oilfield environments was demonstrated by the implementation of a chip temperature-programming system and various versatility tests: a complete C1-C9 alkanes separation was performed in less than 15 s, and complex mixtures fast separations (isomers, unsaturated) were obtained as well; solutions to enable high temperature (100°C) methane- ethane separations were exhibited; use of nitrogen as carrier gas and high humidity levels were shown not to damage sputter-deposited silica columns performances.
A confidential application with GeoServices showed preliminary encouraging results and a development was planned for the year 2014.
Therefore, sputter-deposited stationary phase micro columns opened numerous perspectives for the developments of miniaturized gas chromatographic apparatuses.
Key words: micro gas chromatography, sputtering, MEMS, hydrocarbons, alkanes, silica, alumina, graphite, magnesia, fast separations.