Microfluidics

Our activities in microfluidics address the design, fabrication, and use of simple microfluidic networks for the simultaneous delivery of functionally distinct molecules onto targeted regions of a surface. In our most recent developments, we employ PDMS as a substrate for immunoassays and localize the assays using a wettable microfluidic chip, Figure 1a.

We use capillary pressure as the driving force to move liquids in the various parts of the microfluidic chip, Figure 1b. By tailoring the geometry and wettability of the various parts of the chip, we define distinct functional elements such as filling ports, access channels, vias, retention valves, reaction chambers and capillary pumps. These chips are therefore autonomous capillary systems. Two videos show, respectively, series of liquids loaded successively into one of the four loading pads of a 3D microfluidic chip and some colored liquids flowing in the reaction chamber. In these videos as well as in Figure 1c, the sealing between the Si microfluidic chip and a hydrophobic PDMS surface defines the areas of PDMS where the assay is localized.

Solutions passing through the independent microchannels and reaction chambers bring one or all of the reactants necessary for the deposition of proteins onto the PDMS surface (Figure 2a) or to effect fluorescence surface immunoassays (Figure 2b). With this approach, submicroliter volumes of solutions containing capture antibodies, analyte molecules and detection antibodies suffice to make, within minutes, a highly miniaturized assay to screen for multiple analytes in parallel. We are continuously refining our microfluidic technology to make it ever simpler and more powerful.