Droplet-based assay system
System for performing a flow-based assay. The system may comprise a droplet generator to produce an emulsion including droplets in a carrier fluid. The system also may comprise a thermocycler including two or more temperature-controlled zones and also including a channel connected to the droplet generator for receiving the emulsion. The channel may form a single-pass continuous fluid route traversing the temperature-controlled zones multiple times, such that droplets passing through the channel are thermally cycled. The system further may comprise a detection station downstream from the thermocycler and configured to detect a signal from the droplets after such droplets have been thermally cycled by passing through the channel.
1. A system for performing a flow-based assay, the system comprising:
a droplet generator to produce an emulsion including droplets in a carrier fluid;
a thermocycler including two or more temperature-controlled zones and also including a channel connected to the droplet generator for receiving the emulsion, the channel forming a single-pass continuous fluid route traversing the temperature-controlled zones multiple times, such that droplets passing through the channel are thermally cycled; and
a detection station downstream from the thermocycler and configured to detect a signal from the droplets after such droplets have been thermally cycled by passing through the channel.
2. The system of claim 1 , further comprising a disposable cartridge configured to be removably coupled to the thermocycler, the disposable cartridge containing one or more reagents.
3. The system of claim 2 , wherein the disposable cartridge contains one or more samples.
4. The system of claim 3 , wherein the disposable cartridge includes the droplet generator.
5. The system of claim 1 , wherein the droplet generator is configured to generate a plurality of emulsions separated from one another by spacer liquid.
6. The system of claim 5 , wherein the spacer liquid is labeled to be optically distinguishable from the carrier fluid.
7. The system of claim 1 , further comprising at least one pump configured to drive fluid through the droplet generator.
8. The system of claim 1 , further comprising at least one pump configured to drive the droplets through the channel and the detection station.
9. The system of claim 1 , wherein the thermocycler includes at least three temperature-controlled zones having independently controllable temperatures.
10. The system of claim 1 , wherein the fluid route is helical.
11. The system of claim 10 , wherein the fluid route extends about a central axis, and wherein at least one of the temperature-controlled zones varies in size along the central axis.
12. The system of claim 1 , wherein the thermocycler includes a thermoelectric cooler.
13. The system of claim 12 , wherein the thermocycler includes a thermal core, and wherein the thermoelectric cooler is configured to transfer heat between the thermal core and at least one of the temperature-controlled zones.
14. The system of claim 1 , wherein the thermocycler includes a thermal core and a plurality of segments attached to the thermal core and defining the temperature-controlled zones.
15. The system of claim 1 , wherein the channel is provided by tubing wrapped around a core of the thermocycler.
16. The system of claim 1 , wherein the detection station is an optical detection station configured to detect fluorescence of at least one color from the droplets.
17. The system of claim 16 , wherein the optical detection station is configured to perform multi-color fluorescence detection.
18. The system of claim 1 , further comprising a droplet separation region configured to increase a distance between the droplets downstream of the thermocycler and upstream of a position at which the signal is detected by the detection station.
19. The system of claim 1 , further comprising an analyzer configured to receive data from the detection station and to determine whether a nucleic acid target is present in individual droplets of the emulsion using the data.