Abstract:
A microfluidic flow control device includes a fluidic chamber, a first and a second microfluidic channel, at least one sealing surface between the first and the second channels, and a floating element disposed within the chamber. The floating element is capable of intermittently engaging the sealing surface, and movement of the floating element affects fluid flow between the first channel and the second channel. The floating element may be moved by fluid pressure, gravity, or an applied force such as a magnetic field. Multiple flow control regions may be integrated into a flow control system.
Abstract:
Systems and methods for metering microfluidic volumes are provided. A discrete plug may be separated from a larger volume of first fluid by injecting a second fluid, such as a gas, into a channel containing the first fluid. The injection of the second fluid to isolate the desired amount of the first fluid may be controlled through timing of flows, visual indicators and/or automated control systems using optical or electrical sensors.
Abstract:
Microfluidic fraction collectors fractionating a sample stream into discrete sample volumes are provided. Fluid flow control mechanisms divert selected portions of a sample stream from an inlet channel into one or more branch channels. The fluid flow control mechanisms may be passive, relying on sample volume and fluidic impedance to establish the sample collection sequence. Alternatively, active fluid flow control mechanisms may be controlled, with or without feedback, to establish the sample collection sequence.
Abstract:
Microfluidic devices and methods for metering discrete plugs of fluid are provided. The microfluidic devices include a trunk channel and a branch channel having an impedance region. A fluid is supplied to the trunk channel and fills the branch channel to the impedance region. The fluid is then flushed from the trunk channel leaving the branch channel filled. Because the branch channel has a volume, a discrete plug of the fluid having a volume substantially equal to that of the branch channel is formed.
Abstract:
Microfluidic devices with multiple fluid process regions for subjecting similar samples to different process conditions in parallel are provided. One or more common fluid inputs may be provided to minimize the number of external fluid supply components. Solid materials such as chromatographic separation media or catalyst media is preferably provided in each fluid process region. Solid materials may be supplied to the devices in the form of slurry, with particles retained by porous elements or frits. Different fluid process regions may having different effective lengths, different solid material types or amounts, or may receive different ratios of common fluids supplied to the device. The flow resistances of dissimilar fluid process regions may be balanced passively with the addition of impedance elements in series with each fluid process region.
Abstract:
High throughput liquid chromatography systems include multiple separation columns and multiple flow-through detection regions in sensory communication with a common radiation source and a multi-channel detector. Preferred detector types include a multi-anode photomultiplier tube, a charge-coupled device detector, a diode array, and a photodiode array. In certain embodiments, separation columns are microfluidic and integrated into a unitary microfluidic device. The optical path through a detection region is preferably coaxial with the path of eluate flow along a flow axis through a detection region. On-board or off-board detection regions may be provided.
Abstract:
Microfluidic devices including detection channel geometries that facilitate alignment such detection channels with multiple external sensors are provided. The detection channels include fault tolerant detection channels segments that have a span proportional and parallel to any anticipated positional or dimensional variation of the detection channels with respect to the positions of the multiple external sensors. The detection channels have a substantially constant channel width to minimize pressure-driven channel distortion and dead volumes.
Abstract:
Pressure-driven microfluidic separation devices, such as may be used for performing high performance liquid chromatography, are provided. Multiple separation columns may be defined in a single device and packed with stationary phase material retained by porous frits. One or more splitters may be provided to distribute slurry and/or mobile phase among multiple separation columns. In one embodiment, separation devices are substantially planar and fabricated with multiple device layers. Systems and methods employing slurry for packing separation devices are also provided.
Abstract:
Microfluidic analytical devices and systems have at least one porous element disposed downstream of one or more optical detection regions in a pressure-based separation system. A porous element elevates the backpressure within an optical detection region, thus suppressing bubble formation and enhancing optical detection. Various types of porous elements include porous membranes, packed particulate material, and polymerized monoliths. Preferred devices may be fabricated with substantially planar device layers, including stencil layers, that are directly bonded without adhesives to form a substantially sealed microstructure suitable for performing pressure-based chromatographic separations at elevated operating pressures and with organic solvents.
Abstract:
Microfluidic devices capable of efficiently mixing two or more fluid are provided. Two or more microfluidic inlet channels defined in different sheets of material meet at an overlap region in fluid communication with an outlet channel. The channels are defined through the entire thickness of stencil sheets. The overlap region may include an aperture-defining spacer layer, and/or an impedance element, such as a porous membrane, adapted to distribute at least one fluid across the entire width of the outlet channel to promote reliable fluid mixing.