Method of mixing fluids by coalescence of multiple emulsions

1. A method of sample analysis, comprising:

obtaining a plurality of compound droplets each including at least one sample-containing droplet, at least one reagent-containing droplet, and a barrier fluid that separates the at least one sample-containing droplet from the at least one reagent-containing droplet;

heating compound droplets to induce fusion of at least one of the sample-containing droplet(s) with at least one of the reagent-containing droplet(s) within individual compound droplets to form fused droplets that combine sample and reagent to create assay mixtures for performing an assay;

collecting data from a plurality of the fused droplets; and

determining a result of the assay based on the collected data.

2. The method of claim 1 , wherein the step of heating compound droplets creates an amplification mixture in fused droplets, and wherein the amplification mixture is capable of amplifying a nucleic acid target, if present, in the fused droplets.

3. The method of claim 2 , wherein the at least one reagent-containing droplet of each of the plurality of compound droplets includes at least one primer for amplifying the nucleic acid target.

4. The method of claim 1 , further comprising a step of thermally cycling the fused droplets after the step of heating compound droplets.

5. The method of claim 1 , wherein the step of obtaining includes a step of forming a multiple emulsion including a hydrophilic surfactant and a hydrophobic surfactant.

6. The method of claim 1 , wherein the at least one sample-containing droplet and the at least one reagent-containing droplet of each of the plurality of compound droplets are both encapsulated by the barrier fluid.

7. The method of claim 1 , wherein the barrier fluid is encapsulated by the at least one sample-containing droplet or the at least one reagent-containing droplet of each of the plurality of compound droplets.

8. The method of claim 1 , wherein the step of collecting data including a step of detecting fluorescence intensity signals from a plurality of the fused droplets.

9. The method of claim 1 , wherein the step of determining a result includes a step of determining a presence and/or an activity of an analyte in the sample.

10. The method of claim 1 , wherein the plurality of compound droplets includes a first type of compound droplets and a second type of compound droplets, and wherein each of the first and second types of compound droplets includes a respective distinct code that enables differentiation of the first and second types of droplets, wherein collecting data includes detection of test signals, further comprising (a) a step of detecting code signals from the fused droplets and (b) a step of utilizing the code signals to correlate test signals with the first type and the second type of compound droplets.

11. The method of claim 10 , wherein the first and second types of compound droplets contain distinct reagents or distinct samples, and wherein the step of utilizing the code signals includes a step of correlating test signals with the distinct reagents or samples.

12. The method of claim 10 , wherein the first and second types of compound droplets contain distinct primers for amplification of respective distinct nucleic acid targets, and wherein the step of utilizing the code signals includes a step of correlating test signals with a presence of the distinct nucleic acid targets in the fused droplets.

13. A method of sample analysis, comprising:

selecting an emulsion from a set of pre-formed emulsions each containing a different type of reagent-containing droplet;

forming compound droplets each including at least one sample-containing droplet, at least one reagent-containing droplet from the selected emulsion, and a barrier fluid that separates the at least one sample-containing droplet from the at least one reagent-containing droplet; and

heating compound droplets to induce fusion of at least one of the sample-containing droplet(s) and at least one of the reagent-containing droplet(s) within individual compound droplets to form fused droplets that combine reagent from the selected emulsion with sample to create assay mixtures for performing an assay.

14. The method of claim 13 , wherein the step of selecting an emulsion includes a step of selecting an emulsion from an array of pre-formed emulsions.

15. The method of claim 13 , wherein the step of selecting an emulsion includes a step of selecting one or more primers from a set of different primers contained by the pre-formed emulsions.

16. The method of claim 13 , wherein the step of forming compound droplets includes a step of forming compound droplets each having the at least one sample-containing droplet and the at least one reagent-containing droplet encapsulated by the barrier fluid.

17. The method of claim 13 , the emulsion being a first emulsion, further comprising a step of selecting a second emulsion from a set of pre-formed emulsions each containing a different type of sample-containing droplet, wherein the step of forming disposes at least one droplet of each of the first and second emulsions in each compound droplet.

18. The method of claim 1 , wherein the step of collecting data includes a step of detecting light from a plurality of the fused droplets, and wherein the step of determining a result of the assay is based on the light detected.

19. The method of claim 13 , further comprising:

detecting light from a plurality of the fused droplets; and

determining a result of the assay based on the light detected.