| abstract |
Articles and methods for controlling flow in fluidic systems, especially in microfluidic systems, are provided. In one aspect, a microfluidic system described herein includes a configuration such that the actuation of a single valve can allow the switching of fluids from a first fluid path (e.g., a first channel section) to a second fluid path (e.g., a second channel section). This may be achieved, for example, by incorporating a valve with a first channel section, which may have a lower hydrodynamic resistance than a second channel section prior to actuation of the valve. Actuation of the valve can cause only the hydrodynamic resistance of the first channel section to increase, thereby redirecting fluid flow into the second channel section (which now has a relatively lower hydrodynamic resistance). In some embodiments, the valve comprises a control channel for introducing a positive or reduced pressure, and is adapted to modulate fluid flow in an adjacent channel section by constricting or expanding the channel section. For example, the valve and/or the channel section may be formed in a flexible material and actuation of the valve may be achieved by applying a positive or reduced pressure to the valve to cause deformation of both the valve and the channel section. Another aspect of the invention includes articles and methods associated with manipulation of multiphase materials (e.g., dispersions). For instance, one or more valves may be combined with a flow focusing system so as to form droplets of different volumes and/or frequencies without the need to vary flow rates of the fluids when they are introduced into the fluidic system. |