Microfluidics for Processing Surfaces and Miniaturizing Biological Assays


  • We are very grateful to Bruno Michel, Paul F. Seidler, and Walter Riess for their continuous support of this work. We also would like to thank André Bernard, Hans Biebuyck, Sandro Cesaro-Tadic, Isabelle Caelen, Alexander Papra, Alexander Bietsch, Heiko Wolf, Matthias Geissler, Jean-Philippe Renault, Marc Wolf, Martin Zimmermann, Patrick Hunziker, Steven Bentley, Jennifer Foley, Gregor Dernick, Christof Fattinger, Gerrit Buurman, and Harald Kropshofer for their valuable help with many aspects of our work. We also thank Ute Drechsler, Richard Stutz, and Michel Despont for their expertise in and support with the microfabrication of Si chips, and Govindarajan Natarajan and James Humenik for the development and fabrication of ceramic microfluidic chips and for making Figures 4D,E available to us. We thank Erich Ruetsche, Scott Partington, Matthew Denesuk, Albert Young, Nils Omland, Laurent Malaquin, and Tobias Kraus for helpful discussions, and Charlotte Bolliger for her help with the manuscript.


This review is an account of our efforts to develop a versatile and flexible microfluidic technology for surface-processing applications and miniaturizing biological assays. The review is presented in the context of current trends in microfluidic technology and addresses some of the major challenges for confining chemical and biochemical processes on surfaces: the sealing of a microchannel with a surface, the world-to-chip interface, the displacement of liquids in small conduits, the sequential delivery of multiple solutions, the accurate patterning of surfaces, the coincident detection of various analytes, and the detection of analytes in a small and dilute sample. Our solutions to these problems include the use of reversible sealing, capillary phenomena for powering and controlling liquid transport, and non-contact microfluidics for spotting and drawing (on surfaces) with flow conditions. These solutions offer many advantages over conventional techniques for handling minute amounts of liquids and may find applications in lithography, biopatterning (e.g., the patterning of biomolecules), diagnostics, drug discovery, and also cellular assays.