Systems and methods for droplet production and/or fluidic manipulation

The present invention generally relates to systems and techniques for manipulating fluids and/or making droplets. In certain aspects, the present invention generally relates to droplet production. The droplets may be formed from fluids from different sources. In one set of embodiments, the present invention is directed to a microfluidic device comprising a plurality of droplet-making units, and/or other fluidic units, which may be substantially identical in some cases. Substantially each of the fluidic units may be in fluidic communication with a different source of a first fluid and a common source of a second fluid, in certain embodiments. In one aspect, substantially the same pressure may be applied to substantially all of the different sources of fluid, which may be used to cause fluid to move from the different sources into the microfluidic device. In some cases, the fluids may interact within the fluidic units, e.g., by reacting, or for the production of droplets within the microfluidic device. In some cases, the droplets may be used, for example, to form a library of droplets.