Methods for performing microfluidic sampling

• US 20080105549A1
• Filed: 11/07/2007
• Published: 05/08/2008
• Est. Priority Date: 09/24/2002
• Status: Active Grant

• Current Assignee: Duke University
• Original Assignee: Duke University
• Inventors: Fair, Richard, Pamela, Vamsee, Ren, Hong, Paik, Philip, Pollack, Michael
• Granted Patent: US 8,524,506 B2
• Time in Patent Office: Days
• US Class Current: 204/556
• CPC Class Codes: B01F 33/3021 the components to be mixed being combined in a single independent droplet, e.g. these droplets being divided by a non-miscible fluid or consisting of independent droplets
• CPC Class Codes: B01F 33/3031 using electro-hydrodynamic [EHD] or electro-kinetic [EKI] phenomena to mix or move the fluids
• CPC Class Codes: B01F 33/30351 using hydrophilic/hydrophobic surfaces
• CPC Class Codes: B01J 2219/00479 Means for mixing reactants or products in the reaction vessels
• CPC Class Codes: B01J 2219/00653 the compounds being bound to electrodes embedded in or on the solid supports
• CPC Class Codes: B01L 2300/089 Virtual walls for guiding liquids
• CPC Class Codes: B01L 2300/165 Specific details about hydrophobic, oleophobic surfaces
• CPC Class Codes: B01L 2400/0415 electrical forces, e.g. electrokinetic
• CPC Class Codes: B01L 2400/0427 Electrowetting
• CPC Class Codes: B01L 3/502792 for moving individual droplets on a plate, e.g. by locally altering surface tension
• CPC Class Codes: C40B 60/14 for creating libraries
• CPC Class Codes: G01N 15/14 Optical investigation techniques, e.g. flow cytometry
• CPC Class Codes: G01N 2035/1046 Levitated, suspended drops
• CPC Class Codes: G02B 26/005 based on electrowetting
• CPC Class Codes: Y10T 436/11 Automated chemical analysis
• CPC Class Codes: Y10T 436/113332 with conveyance of sample along a test line in a container or rack
• CPC Class Codes: Y10T 436/117497 with a continuously flowing sample or carrier stream
• CPC Class Codes: Y10T 436/118339 with formation of a segmented stream
• CPC Class Codes: Y10T 436/25 including sample preparation
• CPC Class Codes: Y10T 436/25625 Dilution
• CPC Class Codes: Y10T 436/2575 : Volumetric liquid transfer

Abstract

Methods for sampling a liquid flow are provided. The method includes supplying a continuous liquid flow from a continuous flow fluid input source to a surface along a first flow path. The method additionally includes sampling the continuous liquid flow by performing an electric field-based technique to split off a sample droplet from a portion of the liquid flow, whereby the sample droplet is distinct from the liquid flow and controllable independently of the liquid flow, wherein the electric field-based technique is performed by providing a set of electrodes on the surface and selectively biasing the set of electrodes, whereby the sample droplet is formed on one of the set of electrodes.

Claims

1. A method for sampling a liquid flow, comprising the steps of:

(a) supplying a continuous liquid flow from a continuous flow fluid input source to a surface along a first flow path; and

(b) sampling the continuous liquid flow by performing an electric field-based technique to split off a sample droplet from a portion of the liquid flow, whereby the sample droplet is distinct from the liquid flow and controllable independently of the liquid flow, wherein the electric field-based technique is performed by providing a set of electrodes on the surface and selectively biasing the set of electrodes, whereby the sample droplet is formed on one of the set of electrodes.

2. The method according to claim 1 comprising the step of moving the sample droplet along a second flow path by electric field-based actuation.

3. The method of claim 1 wherein the continuous liquid flow comprises a volume of liquid that has not been discretized into smaller-volume droplets.

4. The method of claim 1 wherein the continuous liquid flow comprises a capillary-scale stream.

5. The method of claim 1 wherein the continuous liquid flow comprises a liquid finger.

6. The method of claim 1 wherein the continuous liquid flow comprises a liquid slug.

7. The method of claim 1 wherein the continuous liquid flow comprises a liquid aliquot.

8. The method of claim 1 wherein the continuous liquid flow comprises a liquid a metered dose of fluid.

9. A method for sampling a liquid flow, comprising the steps of:

(a) supplying a continuous liquid flow from a continuous flow fluid input source to a surface along a first flow path; and

(b) sampling the continuous liquid flow by performing an electric field-based technique to split off a sample droplet from a portion of the liquid flow, whereby the sample droplet is distinct from the liquid flow and controllable independently of the liquid flow, wherein the electric field-based technique is performed by providing a set of electrodes on the surface, placing at least a portion of the liquid flow in communication with at least one conductive element and a first one of the electrodes, and selectively biasing the set of electrodes, whereby the sample droplet is formed on another electrode different from the first electrode.

10. The method according to claim 9 wherein a second one of the electrodes is disposed adjacent to the first electrode and a third one of the electrodes is disposed adjacent to the second electrode, and the electric field-based technique is performed by biasing the first, second and third electrodes to a first voltage to cause the liquid flow portion to spread across the second and third electrodes, and biasing the second electrode to a second voltage different from the first voltage to cause the sample droplet to form on the third electrode.

11. The method of claim 9 wherein the continuous liquid flow comprises a volume of liquid that has not been discretized into smaller-volume droplets.

12. The method of claim 9 wherein the continuous liquid flow comprises a capillary-scale stream.

13. The method of claim 9 wherein the continuous liquid flow comprises a liquid finger.

14. The method of claim 9 wherein the continuous liquid flow comprises a liquid slug.

15. The method of claim 9 wherein the continuous liquid flow comprises a liquid aliquot.

16. The method of claim 9 wherein the continuous liquid flow comprises a liquid a metered dose of fluid.