System for transporting emulsions from an array to a detector
System, including apparatus and methods, for performing droplet-based assays. The system may comprise a droplet transporter configured to pick up droplets from each emulsion of an array of reacted emulsions and to drive flow of the droplets through a detection region. The system also may comprise a detector configured to collect data related to one or more analytes from individual droplets of the reacted emulsions as such individual droplets travel through the detection region. The system further may comprise a controller programmed to determine, based on the data collected, an aspect of the one or more analytes in one or more samples included in droplets of the emulsions.
1. A system for performing a droplet-based assay, comprising:
a droplet transporter including an inlet end, a channel junction, a source of carrier fluid including oil, and a detection region formed by a microfluidic channel, wherein the channel junction is connected to the inlet end, the source, and the detection region, wherein the inlet end is configured to be placed into each well of an array of wells, with each well holding an emulsion including a plurality of droplets disposed in a continuous phase, and wherein the droplet transporter is configured to (a) drive travel of droplets and the continuous phase of each emulsion into the inlet end and from the inlet end to the channel junction, (b) add carrier fluid from the source to the continuous phase at the channel junction, to spatially separate droplets from one another, and (c) drive travel of the spatially separated droplets through the detection region from the channel junction;
a detector configured to collect data related to one or more analytes from individual droplets of each emulsion as such individual droplets travel through the detection region; and
a processor programmed to analyze the data to determine (i) a number of droplets containing at least one copy of an analyte and/or a number of droplets containing no copies of the analyte, and (ii) a concentration of the analyte using at least one of the numbers.
2. The system of claim 1 , wherein each emulsion is an amplified emulsion, and wherein the detector is configured to collect data related to amplification of at least one nucleic acid target in individual droplets of the emulsion.
3. The system of claim 2 , wherein the processor is programmed to determine whether the at least one nucleic acid target is present or absent in each individual droplet based on the data collected.
4. The system of claim 1 , wherein the droplet transporter includes an intake conduit that is connected to the detection region and that includes the inlet end, and wherein the droplet transporter is configured to dispose the inlet end of the intake conduit serially in the emulsions while such emulsions are held in the array of wells, to pick up droplets of each emulsion.
5. The system of claim 4 , wherein the droplet transporter is configured to draw droplets of each emulsion into the intake conduit.
6. The system of claim 1 , wherein the droplet transporter is configured to place a separating fluid between different emulsions picked up successively.
7. The system of claim 6 , wherein the droplet transporter is configured to place air as the separating fluid.
8. The system of claim 7 , wherein the droplet transporter is configured to draw air into the inlet end between contact of the inlet end with different emulsions.
9. The system of claim 6 , wherein the droplet transporter is configured to draw a liquid comprising an oil into the inlet end between contact of the inlet end with different emulsions.
10. The system of claim 1 , wherein the droplet transporter is configured to send droplets serially through the detection region.
11. The system of claim 1 , wherein the detector includes a fluorescence detector.
12. The system of claim 1 , wherein the droplet transporter is configured to drive relative movement of the inlet end and the array of wells along three orthogonal axes.
13. The system of claim 1 , further comprising a plate that provides the array of wells.
14. The system of claim 13 , wherein wells of the plate are spaced according to a well spacing of a standard microplate.
15. The system of claim 1 , further comprising a thermocycler configured to thermally cycle the array of wells each holding an emulsion.
16. The system of claim 1 , further comprising an array of wells that are connected to one another, wherein each well contains an emulsion including a plurality of droplets.