Abstract: A method for fabricating a microfluidic device where first and second substantially flat platens are provided. Multiple substantially planar, substantially metal-free, adhesiveless polymer device layers, the device layers including a first cover layer, second cover layer, and at least one stencil layer defining a microfluidic channel penetrating through the entire thickness of the stencil layer also are provided. Each stencil layer is disposed between other device layers such that the channel is bounded laterally by a stencil layer, and bounded from above and below by surrounding device layers to define an upper channel surface and a lower channel surface. The device layers are stacked between the first platen and the second platen. The stacked device layers are controllably heated according to a heating profile adapted to form a substantially sealed adhesiveless microfluidic device wherein each upper channel surface remains distinct from its corresponding lower channel surface.

Abstract: Microfluidic devices for splitting an established fluidic flow through a microfluidic channel among multiple downstream microfluidic channels include a plurality of elevated flow resistance regions to promote precise and predictable splitting. Each elevated resistance region imparts a flow resistance that is substantially greater than the characteristic resistance to established flow of its associated downstream channel. Elevated flow resistance regions may include one or more porous materials and/or alterations to the channel geometry of at least a portion of a downstream channel.

Abstract: A microfluidic reactor for performing chemical and biological synthesis reactions, including chemical and biological syntheses of organic, polymer, inorganic, oligonucleotide, peptide, protein, bacteria, and enzymatic products is provided. Two fluids are input into the device, mixed in a mixing region and provided to a long, composite reaction channel. Fluids flowing through the reaction channel may be diverted at a diversion region into a sample channel. Fluids in the sample channel may be mixed at a second region, with additional reagents.

Abstract: Modular microfluidic systems includes a plurality of microfluidic modules, each capable of performing fluidic operations including, but not limited to, filtering, splitting, regulating pressure, mixing, metering, reacting, diverting, heating, cooling, and condensing are provided. The microfluidic modules are polymeric, stencil-based structures adapted to be coupled in sequence for performing biological or chemical synthesis, including, but not limited to, chemical and biological syntheses of organic, polymer, inorganic, oligonucleotide, peptide, protein, bacteria, and enzymatic products.

Abstract: A pressure-driven microfluidic device for separating chemical or biological species from a sample includes on-column injection, namely, a separation channel containing stationary phase material and a sample input disposed between a first end and a second end of the separation channel or column. One or many separation channels may be provided in a single microfluidic device, which may be fabricated with sandwiched stencil layers using various materials including polymers. Sealing means associated with a sample input, such as a mechanical seal adapted to selectively seal the sample input, are provide. Various sample injector configurations are provided. A separation system including a microfluidic device having on-column injection further includes a pressure source and a detector.

Abstract: Microfluidic devices for splitting an established fluidic flow through a microfluidic channel among multiple downstream microfluidic channels include a plurality of elevated flow resistance regions to promote precise and predictable splitting. Each elevated resistance region imparts a flow resistance that is substantially greater than the characteristic resistance to established flow of its associated downstream channel. Elevated flow resistance regions may include one or more porous materials and/or alterations to the channel geometry of at least a portion of a downstream channel.

Abstract: An improved method for optically measuring a characteristic of a patient's blood or tissue is provided which involves first passing an arterialization current (typically from about 1-10 mA AC or DC) through a relatively short tissue segment of a patient (up to about 12 inches) for a period of time sufficient to significantly increase blood flow, whereupon a transcutaneous optical measurement is made. The method is especially suited for pulse oximetry and permits more accurate readings owing to the increased amplitude of the detection signal. In another embodiment, a probe molecule composition may be initially applied to the patient's skin, and the arterialization current is used to rapidly and evenly diffuse the probe molecule into the tissue segment. An appropriate sensor can then be employed for detecting the probe molecule.