Lossless droplet transfer of droplet-based microfluidic analysis

1. A transfer structure for droplet-based microfluidic analysis characterized by

A first conduit containing a first stream having at least one immiscible droplet of an aqueous material;

A second conduit containing a second stream comprising an aqueous fluid; and

An interface between the first conduit and the second conduit that defines a plurality of apertures, wherein the apertures are sized to prevent exchange of the first and second streams between conduits while allowing loss-less transfer of droplets from the first conduit to the second conduit through contact between the first and second streams.

2. The transfer structure of claim 1 , wherein the apertures have a smallest dimension between 0.02 μm and 20 μm.

3. The transfer structure of claim 1 , wherein the conduits are not altered with a hydrophilic or hydrophobic treatment.

4. The transfer structure of claim 1 , wherein the apertures vary in size.

5. The transfer structure of claim 4 , wherein the apertures of varying sizes are arranged in a graduated relationship.

6. The transfer structure of claim 1 , further comprising electrodes applying an electrospray-ionization (ESI) potential in the second conduit, wherein the second conduit terminates with an ESI emitter tip directed towards a mass spectrometer.

7. The transfer structure of claim 1 , further comprising an electrode at, or near, each end of the second conduit to apply electric potentials for capillary-electrophoretic (CE) separation, ESI operation, or both.

8. The transfer structure of claim 7 , further comprising an additional channel merging with the second conduit at an ESI emitter tip to form a liquid junction, electrodes applying a potential in the additional channel for CE separation, ESI operation, or both.

9. The transfer structure of claim 1 , wherein the droplet comprises a single cell.

10. The transfer structure of claim 1 , wherein neither the first nor second conduit are formed from glass.

11. The transfer structure of claim 1 , wherein the first conduit, the second conduit, or both are elastomers.

12. The transfer structure of claim 1 , wherein the plurality of apertures compose a porous membrane.

13. The transfer structure of claim 1 , wherein the droplet comprises a fraction of liquid eluted from a liquid chromatography separation.

14. A method for transferring materials in droplet-based microfluidic analytical configurations, the method comprising the steps of:

Flowing a first stream having at least one immiscible droplet of an aqueous material through a first conduit;

Flowing a second stream comprising an aqueous fluid through a second conduit; and

Contacting the first stream with the second stream through an interface defined by a plurality of apertures between the first conduit and the second conduit, wherein the apertures are sized to prevent exchange of the first and second streams between conduits while facilitating loss-less transfer of droplets from the first conduit to the second conduit.

15. The method of claim 14 , further comprising applying potentials to the second conduit for performing ESI.

16. The method of claim 14 , further comprising applying different potentials to the second conduit for performing CE separation, ESI operation, or both.

17. The method of claim 14 , further comprising applying a potential to the second conduit for performing capillary electrophoresis and applying a potential to a third conduit for electrospray ionization, wherein the second and third conduits terminate in proximity to one another at an ESI emitter tip.

18. The method of claim 14 , wherein the droplet comprises a single cell.

19. The method of claim 14 , wherein the first conduit, the second conduit, or both are elastomers.

20. The method of claim 14 , wherein the droplet comprises a fraction of liquid eluted from a liquid chromatography separation.