K. Haffey, E. Higgins, J. Werner, P. Nath
Los Alamos National Laboratory,
Keywords: microfluidics, single cell
Summary:Single cell analysis of genomics, transcriptomics, proteomics, and metabolomics requires a method to isolate, manipulate, and visualize nano-liter samples. Current microfluidic methods to capture single cells such as in microwells, hydrodynamic traps, or dielectrophoretic traps do not typically facilitate on-chip serial processing such as transfection, lysis, washing, and DNA/protein extraction on the isolated cell. Additionally, these methods have limited capabilities to deterministically release the sample for further off-chip processing and analysis. In this work, we present a novel microfluidic platform that can facilitate in situ processing and analysis of a nano-liter sample by trapping, delivering reagents, and mixing in a seamless, continuous operation. This platform is composed of microfluidic traps placed along a central channel as shown in (Fig 1). The traps are comprised of a thin semipermeable membrane separating a pneumatic control channel and a fluid channel. Actuation of the membrane can draw sample from, as well as, return the sample into the microchannel (Fig 2 (a)). The semipermeable membrane allows air caught within the trap to escape. Plugs of aqueous solutions separated by air are created in the central channel such that nanoliter samples can be withdrawn into the traps by the actuation of the membrane. Plugs with different solutions are created in a series such that rapid mixing can take place in the trapped sample as the plugs move pass a trap. This enables automation of serial operations on the nano-liter sample. Mixing time and sample preservation can be optimized for a specific application by altering parameters such as size of traps, plug size, and flow rates. The device is fabricated using a laser based micro-patterning and lamination method. Commercially available 250 micron thick silicone films were integrated as the stretchable, semipermeable membranes. Initial proof of principle is demonstrated using food coloring dye and 60 nano-liter volume traps (Fig 2(b)). We envision diverse applications for single-cell isolation, manipulation and analysis in a single, simple platform.