Microfluidic method and device for transferring mass between two immiscible phases

• US 20060231398A1
• Filed: 03/31/2006
• Published: 10/19/2006
• Est. Priority Date: 04/19/2005
• Status: Active Grant

• Current Assignee: Commissariat a L'Energie Atomique (AES Corporation)
• Original Assignee: Commissariat a L'Energie Atomique (AES Corporation)
• Inventors: Jeanson, Hubert, Sarrut, Nicolas
• Granted Patent: US 8,236,156 B2
• Time in Patent Office: Days
• US Class Current: 204/450
• CPC Class Codes: B01D 11/04 of solutions which are liquid
• CPC Class Codes: B01D 11/0496 by extraction in microfluidic devices

Abstract

A method of transferring mass of at least one solute between a liquid first phase and a fluid second phase that is immiscible with the first phase, the method comprising moving at least one droplet of said liquid first phase in a microfluidic device by using electric-type forces (electrowetting or dielectrophoresis) within a space that is filled with said fluid second phase. Said droplet is preferably moved by said electric-type forces along a path between a point for injecting said droplet into said microfluidic device, and an extraction and/or analysis zone, said path being defined in such a manner that said droplet sweeps through a significant fraction of said space filled with said fluid second phase. The method may include a step of transferring said droplet using said electric-type forces to a chemical analysis device integrated in said microfluidic device, and a step of chemically analyzing said droplet. The invention also provides a device for implementing such a method.

Claims

1. A method of transferring the mass of at least one solute between a liquid first phase and a fluid second phase that is immiscible with the first phase, the method comprising causing at least one droplet of said liquid first phase to move within a microfluidic device under drive from electric-type forces within a space filled with said fluid second phase.

2. A method according to claim 1, comprising moving said droplet with said electric-type forces along a two-dimensional path between a point for injecting or creating said droplet in said microfluidic device, and an extraction and/or analysis zone, said path being determined in such a manner that said droplet sweeps through a fraction comprising at least 20%, preferably at least 50%, and even more preferably at least 80% of said space filled with said fluid second phase.

3. A method according to claim 2, in which said path is a pseudo-random path.

4. A method according to claim 1, in which said fluid second phase flows inside said space of said microfluidic device with its speed being maintained at a value that is slow enough to enable said droplet of said liquid first phase to be moved using said electric-type forces.

5. A method according to claim 1, in which said liquid first phase initially contains a solute, and said fluid second phase presents an affinity for said solute that is not less that of said liquid first phase, thereby causing said droplet to become depleted in solute.

6. A method according to claim 1, in which said fluid second phase initially contains a solute, and said liquid first phase presents an affinity for said solute that is greater than that of said fluid second phase, thereby causing said droplet to become enriched in solute.

7. A method according to claim 1, in which said droplet of said liquid first phase is moved by electrowetting making use of a conductivity difference between said liquid first phase and said fluid second phase, said phases being maintained in contact with a matrix of electrodes and with a counter-electrode between which potential differences can be established.

8. A method according to claim 7, in which said liquid first phase presents conductivity less than that of said fluid second phase and in which said droplet is moved from a position corresponding to a starting electrode to a position corresponding to a destination electrode by maintaining said destination electrode at the same potential as said counter-electrode while a potential difference is established between said counter-electrode and the starting electrode and also the adjacent electrodes.

9. A method according to claim 7, in which said liquid first phase presents conductivity greater than that of said fluid second phase and in which said droplet is moved from a position corresponding to starting electrode to a position corresponding to a destination electrode by establishing a potential difference between said destination electrode and said counter-electrode, while said starting electrode and the adjacent electrodes are maintained at the same potential as said counter-electrode.

10. A method according to claim 8, in which said conductivity difference between said liquid first phase and said fluid second phase is not less than a factor of 10 and preferably not less than a factor of 100.

11. A method according to claim 1, in which said droplet of said liquid first phase is moved by dielectrophoresis by making use of a difference in electrical permeability between said liquid first phase and said fluid second phase, said phases being maintained in contact with a matrix of electrodes and with a counter-electrode between which potential differences can be established.

12. A method according to claim 11, in which said difference in electrical permeability between said liquid first phase and said fluid second phase is not less than 10%, and is preferably not less than 50%.

13. A method according to claim 1, including a step of transferring said droplet using said electric-type forces to a chemical analysis device integrated in said microfluidic device, and a step of chemically analyzing said droplet.

14. A method according to claim 13, in which said analysis step comprises spectrophotometric analysis of said droplet.

15. A method according to claim 13, in which said analysis step comprises a step of electronebulizing said droplet in a mass spectrometer.

16. A method according to claim 1, in which said droplet of said liquid first phase has a volume lying in the range 10 nL to 10 μ

L, and preferably in the range 100 nL to 1 μ

L.

17. A device for implementing the method according to claim 1, the device comprising:

a bottom plate having a matrix of electrodes;

a counter-electrode facing said matrix of electrodes;

means for injecting or creating droplets of a liquid first phase on the surface of said bottom plate;

means for injecting on the surface of said bottom plate a fluid second phase in which the droplets of said liquid first phase are immersed; and

a control device for independently establishing a potential difference between each electrode of said matrix and said counter-electrode so as to define movements of said droplets inside the volume of said fluid second phase.

18. A device according to claim 17, further comprising means for chemically analyzing said droplets.

19. A device according to claim 17, further comprising means for evacuating the fluid second phase so as to establish a flow thereof over the surface of said bottom plate.

20. A device according to claim 17, further comprising a top plate parallel to said bottom plate co-operating therewith to define a space that can be filled with said fluid second phase and carrying said counter-electrode.

21. A device according to claim 17, in which counter-electrode is constituted by at least one conductor wire immersed or tensioned in at least one of said fluid phases.

22. A device according to claim 17, in which said control device is provided to define movement of said droplets along a path enabling them to sweep through at least 20%, preferably at least 50%, and more preferably at least 80% of the volume of said fluid second phase.