Digital analyte analysis

Abstract

The invention generally relates to detecting target molecules.

What is claimed is: 
     
         1 . A method of detecting a target molecule, the method comprising:
 providing a plurality of droplets, wherein one or more droplets comprise a target molecule;   flowing the plurality of droplets through a microfluidic channel, wherein the plurality of droplets are not single-file within a portion of the channel; and   flowing a plurality of droplets simultaneously past a detector, thereby detecting the target molecule in one or more of the droplets.   
     
     
         2 . The method of  claim 1 , wherein the target molecule is selected from the group consisting of: a nucleic acid, a protein, an antibody, an aptamer, a cell, and a microorganism. 
     
     
         3 . The method of  claim 1 , wherein prior to the providing step, the method comprises forming the plurality of droplets. 
     
     
         4 . The method of  claim 1 , wherein the plurality of droplets are aqueous droplets in an immiscible fluid. 
     
     
         5 . The method of  claim 4 , wherein the immiscible fluid is oil. 
     
     
         6 . The method of  claim 4 , wherein the oil comprises a surfactant. 
     
     
         7 . The method of  claim 6 , wherein the surfactant is a fluorosurfactant. 
     
     
         8 . The method of  claim 5 , wherein the oil is a fluorinated oil. 
     
     
         9 . The method of  claim 1 , wherein a plurality of the droplets comprise no more than a single target molecule. 
     
     
         10 . The method of  claim 1 , wherein one or more droplets are empty. 
     
     
         11 . A method for diagnosing a condition, the method comprising:
 providing a plurality of droplets, wherein a subset of droplets comprise nucleic acid from a sample;   amplifying nucleic acid within the droplets;   detecting a signal above background for only droplets that comprise amplified nucleic acid; and   determining a ratio of a first type of nucleic acid to a second type of nucleic acid from the detected droplets, wherein the ratio is indicative of a condition.   
     
     
         12 . The method of  claim 11 , wherein one or more droplets are empty. 
     
     
         13 . The method of  claim 12 , wherein detecting comprising:
 setting a threshold level on a detector that is above an optical signal emitted by the empty droplets; and   recording an optical signal above the threshold level emitted by droplets that comprise amplified nucleic acid.   
     
     
         14 . The method of  claim 11 , wherein a plurality of the droplets comprise no more than a single nucleic acid. 
     
     
         15 . The method of  claim 11 , wherein prior to the providing step, the method comprises forming the plurality of droplets. 
     
     
         16 . The method of  claim 11 , wherein the plurality of droplets are aqueous droplets in an immiscible fluid. 
     
     
         17 . The method of  claim 16 , wherein the immiscible fluid is oil. 
     
     
         18 . The method of  claim 17 , wherein the oil comprises a surfactant. 
     
     
         19 . The method of  claim 18 , wherein the surfactant is a fluorosurfactant. 
     
     
         20 . The method of  claim 17 , wherein the oil is a fluorinated oil.