Manipulating droplet size

Abstract

The invention generally relates to methods and systems for manipulating droplet size. In certain aspects, the invention provides methods for manipulating droplet size that include forming droplets of aqueous fluid surrounded by an immiscible carrier fluid, and manipulating droplet size during the forming step by adjusting pressure exerted on the aqueous fluid or the carrier fluid.

1 - 17 . (canceled) 
     
     
         18 . A microfluidic apparatus comprising:
 a plurality of microfluidic circuits, each circuit comprising:
 a first fluid channel comprising a first resistance and a first fluid; 
 a second fluid channel, comprising a second resistance and a second fluid that is immiscible with the first fluid; 
 a junction where the first fluid channel and the second fluid channel meet such that a plurality of droplets are formed; and 
 an outlet channel that exits the junction and receives the droplets; 
   wherein the first and second resistances of the microfluidic circuits are configured such that variation in pressure exerted on the first fluid in each circuit results in a change in flow rate of the second fluid and a change in a dimension of the droplets.   
     
     
         19 . The microfluidic apparatus of  claim 18 , wherein the change in flow rate of the second fluid is an inverse change to the variation in pressure of the first fluid. 
     
     
         20 . The microfluidic apparatus of  claim 18 , wherein the droplets flow in the second fluid through the outlet channel. 
     
     
         21 . The microfluidic apparatus of  claim 18 , wherein the change in dimension of the droplets allows for control of coalescence of the droplets from a first microfluidic circuit with droplets from a second microfluidic circuit. 
     
     
         22 . The microfluidic apparatus of  claim 18 , wherein the junction comprises a nozzle. 
     
     
         23 . The microfluidic apparatus of  claim 18 , wherein the outlet channel from each of the microfluidic circuits connects to the same main channel. 
     
     
         24 . The microfluidic apparatus of  claim 23 , wherein the main channel connects to one or more analysis modules. 
     
     
         25 . The microfluidic apparatus of  claim 24 , wherein the analysis modules comprise a merging module, an amplification module, a detection module, and a sorting module. 
     
     
         26 . The microfluidic apparatus of  claim 18 , wherein the first fluids in the microfluidic circuits are different from each other. 
     
     
         27 . The microfluidic apparatus of  claim 18 , wherein the first fluids in the microfluidic circuits are the same. 
     
     
         28 . The microfluidic apparatus of  claim 18 , wherein the variation in pressure is exerted on the first fluid in all of the microfluidic circuits independently. 
     
     
         29 . A microfluidic apparatus comprising:
 a plurality of microfluidic circuits each configured to produce droplets; and   a regulator operably associated with each microfluidic circuit that controls pressure exerted on a first fluid that causes a change in flow rate of a second fluid, and adjusts a dimension of the droplets from each microfluidic circuit.   
     
     
         30 . The microfluidic apparatus of  claim 29 , wherein each microfluidic circuit comprises:
 a first fluid channel comprising a first resistance and the first fluid;   a second fluid channel comprising a second resistance and the second fluid that is immiscible with the first fluid;   a junction where the first fluid channel and the one or more second fluid channels meet such that a plurality of the droplets are formed; and   an outlet channel that exits the junction and receives the droplets;   
       wherein the first and second resistances of the microfluidic circuits are configured such that variation in pressure exerted on the first fluid in each circuit results in the change in flow rate of the second fluid and a change in the dimension of the droplets. 
     
     
         31 . The microfluidic apparatus of  claim 29 , wherein the pressure regulator associated with each circuit controls pressure exerted on the first fluid in each microfluidic circuit. 
     
     
         32 . The microfluidic apparatus of  claim 29 , wherein a second pressure regulator controls pressure exerted on the second fluid in all of the microfluidic circuits. 
     
     
         33 . The microfluidic apparatus of  claim 29 , further comprising a pressure source that provides pressure exerted on the first fluid in the microfluidic circuits. 
     
     
         34 . The microfluidic apparatus of  claim 33 , wherein the pressure source provides pressure exerted on the second fluid in the microfluidic circuits. 
     
     
         35 . The microfluidic apparatus of  claim 30 , wherein the junction comprises a nozzle. 
     
     
         36 . The microfluidic apparatus of  claim 30 , wherein the outlet channel from each of the microfluidic circuits connects to the same main channel. 
     
     
         37 . The microfluidic apparatus of  claim 36 , wherein the main channel connects to one or more analysis modules. 
     
     
         38 . The microfluidic apparatus of  claim 37 , wherein the analysis modules comprise a merging module, an amplification module, a detection module, and a sorting module.