Devices and methods for generating and recovering droplets

1. A method of producing droplets, the method comprising steps (a) to (d) in the following order:

a) providing a device for producing droplets of a first liquid in a second liquid, the device comprising:

i) a first channel having a first depth, a first width, a first proximal end, and a first distal end;

ii) a droplet formation region in fluid communication with the first channel; and

iii) a collection reservoir in fluid communication with the droplet formation region and configured to collect droplets formed in the droplet formation region, wherein the collection reservoir comprises a lumen configured to accept a collection device, and wherein a boundary of the lumen has an angle of between ±45 degrees from surface normal to the horizontal surface;

wherein the first channel and droplet formation region are configured to produce droplets of the first liquid in the second liquid;

b) inserting a collection device into the lumen;

c) producing the droplets; and

d) passively collecting the droplets in the collection device.

2. The method of claim 1 , wherein the collection device is a pipette tip and the droplets flow from the collection reservoir into the pipette tip or wherein the collection device comprises a tube having a proximal end and a distal end, wherein the proximal end is in fluid communication with the lumen and the distal end is in fluid communication with an external container and the collecting step (d) further comprises moving the droplets from the collection reservoir to the external container with a displacement fluid.

3. A method for producing droplets of a first liquid in a second liquid, the method comprising steps (a) to (d) in the following order:

a) providing a device comprising:

i) a first channel having a first depth, a first width, a first proximal end, and a first distal end;

ii) a droplet formation region in fluid communication with the first channel;

iii) a collection reservoir in fluid communication with the droplet formation region and configured to collect droplets formed in the droplet formation region, wherein the first channel and droplet formation region are configured to produce first droplets of the first liquid in the second liquid, wherein the first droplets comprise a sample; and

iv) a droplet or particle source in fluid communication with the collection reservoir, wherein the droplet or particle source does not comprise the sample;

b) allowing the first liquid to flow from the first channel to the droplet formation region to produce the first droplets;

c) collecting the first droplets in the collection reservoir; and

d) allowing the droplet or particle source to provide second droplets and/or particles to the collection reservoir, wherein each second droplet and/or particle does not comprise the sample, and wherein the particles are solid or semi-solid.

4. The method of claim 3 , wherein the droplet formation region and the droplet or particle source simultaneously provide droplets or particles to the collection reservoir.

5. The method of claim 4 , wherein the rate of droplets produced by the droplet formation region is less than the rate of particles or droplets provided by the droplet or particle source to the collection reservoir.

6. A method for processing a sample, the method comprising steps (a) to (d) in the following order:

a) providing a device for producing droplets of a first liquid in a second liquid, the device comprising:

(i) a first channel having a first depth, a first width, a first proximal end, and a first distal end;

(ii) a droplet formation region in fluid communication with the first channel;

(iii) a collection reservoir in fluid communication with the droplet formation region and configured to collect droplets formed in the droplet formation region, the collection reservoir having a top portion and a bottom portion;

(iv) an oil shunt channel controllably in fluid communication with the bottom portion or configured to be controllably in fluid communication with the bottom portion;

(v) one or more access channels configured to be controllably in fluid communication with the top portion of the collection reservoir; and

(vi) one or more thermal elements disposed to alter the temperature of the collection reservoir,

wherein the first channel and the droplet formation region are configured to produce droplets of the first liquid in the second liquid;

b) allowing the device to produce droplets of the sample to form an emulsion in the second liquid;

c) heating and/or cooling the emulsion thereby processing the sample; and

d) breaking the emulsion inside the collection reservoir to produce a liquid layer from the droplets of the sample in the collection reservoir.

7. The method of claim 6 , further comprising removing the liquid layer from the collection reservoir.

8. The method of claim 6 , wherein the emulsion is broken by the introduction of a reagent.

9. The method of claim 8 , wherein the reagent is introduced via a first of the one or more access channels.

10. The method of claim 1 , wherein the collection device comprises a pipette tip or a tube having a proximal end and a distal end, wherein the proximal end is in fluid communication with the lumen and the distal end is in fluid communication with an external container.

11. The method of claim 1 , wherein the device further comprises a second channel having a second depth, a second width, a second proximal end, and a second distal end, wherein the second channel intersects the first channel between the first proximal and first distal ends.

12. The method of claim 1 , wherein the droplet formation region comprises a shelf having a third depth, a third width, at least one inlet, and at least one outlet, wherein the shelf is configured to allow the first liquid to expand in at least one dimension and a step having a fourth depth.

13. The method of claim 1 , wherein the device further comprises a reservoir configured to be controllably in fluid communication with the collection reservoir.

14. The method of claim 13 , wherein the reservoir comprises an immiscible displacement fluid.

15. The method of claim 6 , wherein the device comprises two access channels.