Microfluidic gasketless interconnects sealed by superhydrophobic surfaces.

Existing methods for sealing chip-to-chip (or module-to-motherboard) microfluidic interconnects commonly use additional interconnect components (O-rings, gaskets, and tubing), and manual handling expertise for assembly. Novel gasketless superhydrophobic fluidic interconnects (GSFIs) sealed by transparent superhydrophobic surfaces, forming liquid bridges between the fluidic ports for fluidic passages were demonstrated. Two test platforms were designed, fabricated, and evaluated, a multi-port chip system (ten interconnects) and a modules-on-a-motherboard system (four interconnects). System assembly in less than 3 sec was done by embedded magnets and pin-in-V-groove structures. Flow tests with deionized (DI) water, ethanol/water mixture, and plasma confirmed no leakage through the gasketless interconnects up to a maximum flow rate of 100 µL/min for the multi-port chip system. The modules-on-a-motherboard system showed no leakage of water at a flow rate of 20 µL/min and a pressure drop of 3.71 psi. Characterization of the leakage pressure as a function of the surface tension of the sample liquid in the multi-port chip system revealed that lower surface tension of the liquid led to lower static water contact angles on the superhydrophobic-coated substrate and lower leakage pressures. The high-density, rapidly assembled, gasketless interconnect technology will open up new avenues for chip-to-chip fluid transport in complex microfluidic modular systems.

96-well polycarbonate-based microfluidic titer plate for high-throughput purification of DNA and RNA.

We report a simple and effective method for the high-throughput purification of a variety of nucleic acids (NAs) from whole cell lysates or whole blood using a photactivated polycarbonate solid-phase reversible immobilization (PPC-SPRI) microfluidic chip. High-throughput operation was achieved by placing 96 purification beds, each containing an array of 3800 20 microm diameter posts, on a single 3" x 5" polycarbonate (PC) wafer fabricated by hot embossing. All beds were interconnected through a common microfluidic network that permitted parallel access through the use of a vacuum and syringe pump for delivery of immobilization buffer (IB) and effluent. The PPC-SPRI purification was accomplished by condensation of NAs onto a UV-modified PC surface in the presence of the IB comprised of polyethylene glycol, NaCl, and ethanol with a composition dependent on the length of the NAs to be isolated and the identity of the sample matrix. The performance of the device was validated by quantification of the recovered material following PCR (for DNA) or RT-PCR (for RNA). The extraction bed load capacity of NAs was 206 +/- 93 ng for gDNA and 165 +/- 81 ng for TRNA from Escherichia coli. Plate-to-plate variability was found to be 35 +/- 10%. The purification process was fast (<30 min) and easy to automate, and the low cost of wafer fabrication makes it appropriate for single-use applications.