Systems and methods for droplet production and/or fluidic manipulation

A method, comprising:

• providing, in a pressure chamber, a microfluidic device comprising a plurality of droplet-making units, each of the droplet-making units comprising one or more channels, each of the droplet-making units being substantially planar, each of the droplet-making units in fluidic communication with a different source of droplet fluid, and with a common source of carrier fluid via two or more substantially parallel channels in fluidic communication with the plurality of droplet-making units, wherein all of the different sources of droplet fluid are open to a common environment within the pressure chamber;
• applying, via the common environment, the same pressure and/or pressure drop to all of the different sources of droplet fluid to cause droplet fluid to move from the different sources of droplet fluid into the microfluidic device by increasing the pressure of the surrounding environment, wherein applying the same pressure and/or pressure drop comprises introducing a pressurizing fluid comprising air to all of the different sources of droplet fluid;
• controlling the variability in flow resistance between the plurality of droplet-making units by flowing the droplet fluid through at least one channel within each droplet-making unit, the at least one channel having a length greater than two times the largest dimension of the droplet-making unit, such that the largest contribution of flow resistance between the plurality of droplet-making units is controlled by said length of the at least one channel;
• and
• producing, within the microfluidic device, a library of droplets, the library of droplets being contained within the carrier fluid from the source of carrier fluid;
• wherein the library of droplets comprises:
• a first plurality of droplets of the library containing a first species at a first concentration, and
• a second plurality of droplets of the library, the second plurality of droplets comprising the first species at a second concentration different from the first concentration, or comprising a second species different from the first species,
• wherein each produced droplet exits each droplet-making unit via one or more outlets into a collection channel, the collection channel in fluidic communication with the plurality of droplet-making units, wherein the one or more outlets has an increasing cross- sectional area;
• and
• flowing the library of droplets in the collection channel.

A method, comprising:

• providing, in a pressure chamber, a microfluidic device comprising a plurality of droplet-making units and a plurality of substantially parallel channels therein configured to distribute carrier fluid from a common source of carrier fluid to substantially each of the droplet-making units, each of the droplet-making units comprising one or more channels, wherein each of the droplet-making units is in fluidic communication with a different source of droplet fluid and the common source of carrier fluid and wherein each of the droplet- making units are substantially planar;
• applying the same pressure and/or pressure drop to all of the different sources of droplet fluid and the common source of carrier fluid to cause droplet fluid to move from the different sources of droplet fluid into the microfluidic device and to cause carrier fluid to move from the common source of carrier fluid into the microfluidic device, wherein applying the same pressure and/or pressure drop to all of the different sources of droplet fluid and the common source of carrier fluid comprises applying a common pressure from a pressure source;
• controlling the variability in flow resistance between the plurality of droplet-making units by flowing the droplet fluid through at least one channel within each droplet-making unit, the at least one channel having a length greater than two times the largest dimension of the droplet-making unit, such that the largest contribution of flow resistance between the plurality of droplet-making units is controlled by said length of the at least one channel;
• and
• producing, within the microfluidic device, a library of droplets, the library of droplets being contained within the carrier fluid from the common source of carrier fluid;
• wherein the library of droplets comprises:
• a first plurality of droplets of the library containing a first species at a first concentration, and
• a second plurality of droplets of the library, the second plurality of droplets comprising the first species at a second concentration different from the first concentration, or comprising a second species different from the first species,
• wherein each produced droplet exits each droplet-making unit via one or more outlets into a collection channel, the collection channel in fluidic communication with the plurality of droplet-making units, wherein the one or more outlets has an increasing cross- sectional area;
• and
• flowing the library of droplets in the collection channel.