An enduring challenge for chip-scale gas chromatographs has been the integration of pumps and valves that are necessary to handle analyte samples. Microscale pumps have been studied for more than two decades, and successful pumping has been reported for gas phase fluids. A common approach has been to use membrane actuation. In recent years, it has been shown that motionless gas pumps that are based on thermal transpiration – specifically, Knudsen pumps (KPs) – are effective for both vacuum and high-flow applications when appropriately configured. Being motionless, KPs are silent and highly reliable. This presentation will describe how lithographic manufacturing methods may be used for high flow Knudsen pumps. It will also describe an example of how the architecture of micro gas chromatographs can be adapted to incorporate KPs. In this example a fully microfabricated system is used to evaluate a mixture of volatile organic compounds that includes benzene, toluene, and xylene. This research is performed in the context of the University of Michigan Center for Wireless Integrated MicroSensing and Systems (WIMS2). This multi-disciplinary Center currently includes about 35 faculty, and 100 PhD students and postdoctoral scholars. The Center brings together research in core technologies such as MEMS, micropower circuits, and RF technology, to facilitate microsystems for healthcare, environmental monitoring, and infrastructure monitoring.
Yogesh B. Gianchandani is a Professor at the University of Michigan, Ann Arbor, with a primary appointment in the Electrical Engineering and Computer Science Department and a courtesy appointment in the Mechanical Engineering Department. He also serves as the Director for the Center for Wireless Integrated MicroSensing and Systems (WIMS2). Dr. Gianchandani’s research interests include all aspects of design, fabrication, and packaging of micromachined sensors and actuators (http://www.eecs.umich.edu/~yogesh/). He has graduated over 30 Ph.D. students, and contributed to over 45 US patents and over 300 papers in journals and conferences. He was a Chief Co-Editor of Comprehensive Microsystems: Fundamentals, Technology, and Applications, published in 2008, and he serves on the editorial boards and program committees of a number of journals and conferences. From 2007 to 2009 he also served at the National Science Foundation, as the program director for Micro and Nano Systems within the Electrical, Communication, and Cyber Systems Division (ECCS). Dr. Gianchandani is a Fellow of IEEE.