Methods for performing microfluidic sampling

• US 20070037294A1
• Filed: 10/23/2006
• Published: 02/15/2007
• Est. Priority Date: 09/24/2002
• Status: Active Grant

• Current Assignee: Duke University
• Original Assignee: Duke University
• Inventors: Pamula, Vamsee, Pollack, Michael, Fair, Richard
• Granted Patent: US 7,759,132 B2
• Time in Patent Office: Days
• US Class Current: 436/180
• 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 performing microfluidic sampling are provided. The method includes providing a substrate including an arrangement of first, second and third electrodes, wherein the second electrode is interposed between the first and third electrodes. The method additionally includes causing a fluid input to continuously flow to the first electrode and biasing the first, second and third electrodes to a first voltage to cause a portion of the fluid input to spread across the second and third electrodes. The method further includes biasing the second electrode to a second voltage different from the first voltage to form a droplet on the third electrode, the droplet being separate from the fluid input.

Claims

1. A method for performing microfluidic sampling, comprising the steps of:

(a) providing a substrate comprising an arrangement of first, second and third electrodes, wherein the second electrode is interposed between the first and third electrodes;

(b) causing a fluid input to continuously flow to the first electrode;

(c) biasing the first, second and third electrodes to a first voltage to cause a portion of the fluid input to spread across the second and third electrodes; and

(d) biasing the second electrode to a second voltage different from the first voltage to form a droplet on the third electrode, the droplet being separate from the fluid input.

2. The method according to claim 1 wherein the fluid input flow stream flows across the substrate along an input direction, and the second and third electrodes are disposed along the input direction.

3. The method according to claim 1 wherein the fluid input flow stream flows across the substrate along an input direction, and the second and third electrodes are disposed along a transport direction different from the input direction.

4. The method according to claim 1 comprising the step of moving the droplet to a processing area of the substrate by biasing a selected set of additional electrodes.

5. The method according to claim 1 comprising the step of forming a plurality of droplets by repeating steps (c) and (d) a desired number of times.

6. The method according to claim 5 comprising the step of recombining two or more of the droplets on the substrate to form a fluid output flow stream.

7. The method according to claim 1 wherein the fluid input in step (b) flows from a stationary reservoir on the substrate or flows from a reservoir coupled to the substrate.

8. The method according to claim 1 wherein the fluid input comprises a capillary-scale stream.

9. The method according to claim 1 wherein the fluid input comprises a continuous flow finger.

10. The method according to claim 1 wherein the fluid input comprises continuous flow slug.

11. The method according to claim 1 wherein the fluid input comprises continuous flow aliquot.

12. The method according to claim 1 wherein the fluid input comprises continuous flow of metered doses.

13. The method according to claim 1 wherein the fluid input is introduced from a plane that is separate from the plane of the substrate.

14. The method according to claim 1 wherein the fluid input comprises an analyte substance of interest.