Droplet Actuator Loading and Target Concentration

• US 20100062508A1
• Filed: 03/24/2008
• Published: 03/11/2010
• Est. Priority Date: 03/23/2007
• Status: Active Grant

• Current Assignee: Advanced Liquid Logic, Inc. (Illumina Incorporated)
• Original Assignee: Advanced Liquid Logic, Inc. (Illumina Incorporated)
• Inventors: Pamula, Vamsee K., Srinivasan, Vijay, Pollack, Michael G.
• Granted Patent: US 8,317,990 B2
• Time in Patent Office: Days
• US Class Current: 435/174
• 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: B01L 2200/0605 Metering of fluids
• CPC Class Codes: B01L 2200/0647 Handling flowable solids, e.g. microscopic beads, cells, particles
• CPC Class Codes: B01L 2200/0668 Trapping microscopic beads
• CPC Class Codes: B01L 2200/0673 Handling of plugs of fluid surrounded by immiscible fluid
• CPC Class Codes: B01L 2300/0636 Integrated biosensor, microarrays
• CPC Class Codes: B01L 2300/0816 Cards, e.g. flat sample carriers usually with flow in two horizontal directions
• CPC Class Codes: B01L 2300/0861 Configuration of multiple channels and/or chambers in a single devices
• CPC Class Codes: B01L 2300/0867 Multiple inlets and one sample wells, e.g. mixing, dilution
• CPC Class Codes: B01L 2300/089 Virtual walls for guiding liquids
• CPC Class Codes: B01L 2400/0427 Electrowetting
• CPC Class Codes: B01L 2400/0487 fluid pressure, pneumatics
• CPC Class Codes: B01L 3/502761 specially adapted for handling suspended solids or molecules independently from the bulk fluid flow, e.g. for trapping or sorting beads, for physically stretching molecules investigating characteristics of particles G01N15/00
• CPC Class Codes: B01L 3/502792 for moving individual droplets on a plate, e.g. by locally altering surface tension
• CPC Class Codes: C25B 15/00 Operating or servicing cells
• CPC Class Codes: G01N 33/5438 Electrodes

Abstract

A droplet actuator and method of providing a droplet comprising an target substance on the droplet actuator, and including discrete flow and continuous flow functionality. Discrete flow function is controlled by electrodes arranged for conducting droplet operations on a substrate surface. The continuous flow function includes a fluid path arranged for flowing a fluid therethrough. The discrete flow and continuous flow functions may be by a barrier, including a second fluid path through the barrier. The continuous flow function may include a capture surface comprising a component having an affinity for the target substance. Methods of the invention may include flowing a fluid comprising the target substance through the fluid path; capturing the target substance on the capture surface; and forming a droplet in the discrete flow region via the second fluid path and the electrodes comprising the captured target substance.

Claims

1. A method of providing a droplet comprising an target substance on a droplet actuator, the method comprising:

(a) providing a droplet actuator comprising a substrate comprising;

(i) a discrete flow section comprising electrodes arranged for conducting droplet operations on a substrate surface;

(ii) a continuous flow section comprising a fluid path arranged for flowing a fluid therethrough, and separated from the discrete flow section by a barrier;

(iii) an opening in the barrier arranged relative to the electrodes such that fluid in the fluid path is in proximity to one or more of the electrodes;

(iv) a capture surface comprising a component having an affinity for the target substance;

(b) flowing a fluid comprising the target substance through the fluid path;

(c) capturing the target substance on the capture surface; and

(d) forming a droplet comprising the captured target substance in the discrete flow section.

2. The method of claim 1 further comprising transporting the target substance through the opening and into the discrete flow section.

3. The method of claim 1 wherein step 1(d) comprises conducting droplet operations using the electrodes to draw fluid comprising the sample of interest through the opening and forming a droplet therefrom.

4. The method of claim 1 wherein the droplet actuator further comprises sample collection beads immobilized in the fluid path such that a target substance in a fluid flowing through the fluid path is collected on the beads, and step 1(d) comprises transporting a droplet comprising the beads through the opening and into the droplet actuation region.

5. The method of claim 1 wherein the droplet formed in step 1(d) is at least partially surrounded by a filler fluid.

6. The method of claim 1 wherein the droplet formed in step 1(d) is substantially completely surrounded by a filler fluid.

7. The method of claim 1 wherein the droplet formed in step 1(d) comprises one or more beads.

8. The method of claim 1 wherein the droplet formed in step 1(d) comprises one or more biological cells.

9. The method of claim 1 wherein the width of the opening is smaller than the height of the fluid path.

10. The method of claim 1 wherein the continuous flow section comprises a second set of electrodes arranged for conducting droplet operations, and the method further comprises:

(a) forming one or more sample droplets on the second set of electrodes; and

(b) transporting said one or more sample droplets into the discrete flow section.

11. The method of claim 1 wherein the continuous flow section comprises a second set of electrodes arranged for conducting droplet operations, and the method further comprises:

(a) forming one or more sample droplets on the second set of electrodes; and

(b) using the second set of electrodes to transport said one or more sample droplets into proximity with electrodes in the discrete flow section.

12. The method of claim 1 comprising two or more capture surfaces in the continuous flow section.

13. The method of claim 12 wherein the two or more capture surfaces each comprise a population of beads, wherein each population has affinity for a different target substance.

14. The method of claim 13 wherein the beads are maintained in place by one or more physical barriers.

15. The method of claim 13 wherein the beads are magnetically responsive and are maintained in place by one or more magnetic fields.

16. The method of claim 15 wherein the magnetic field comprises a magnetic field produced by an electromagnet.

17. The method of claim 15 wherein the magnetic field comprises a magnetic field produced by a permanent magnet.

18. The method of claim 1 wherein step 1(c) comprises combining one or more beads having affinity for the target substance with a fluid comprising the target substance prior to introduction of the fluid into the fluid path.

19. The method of claim 1 wherein the target substance comprises an analyte of interest.

20. The method of claim 1 wherein the target substance comprises a product of a chemical reaction.

21. The method of claim 1 wherein the target substance comprises a bead.

22. The method of claim 1 wherein the target substance comprises a biological cell.

23. The method of claim 1 wherein the target substance comprises a bead comprising an analyte of interest and/or a product of a chemical reaction.

24. The method of claim 1 wherein the discrete flow section is separated from the continuous flow section by a reservoir comprising a reservoir electrode.

25. The method of claim 24 wherein the method comprises:

(a) flowing a fluid comprising the substance of interest from the fluid path into the reservoir; and

(b) dispensing droplets from the reservoir onto one or more electrodes in the discrete flow section.

26. The method of claim 1 wherein step 1(b) comprises forcing fluid through the fluid path using a pressure source.

27. The method of claim 26 wherein the pressure source comprises a syringe coupled to the fluid path.

28. The method of claim 1 wherein step 1(d) comprises activating one of more electrodes in the discrete flow section adjacent to the opening to cause fluid to flow from the fluid path into the discrete flow section and form the droplet.

29. The method of claim 1 wherein step 1(d) comprises forcing fluid from the fluid path through the opening into the discrete flow section into proximity with one or more electrodes, and conducting droplet operations using the one of more electrodes to form the droplet.

30. The method of claim 29 wherein the forcing fluid step comprises causing a pressure in the fluid path which forces fluid through the opening into the discrete flow section into proximity with the one or more electrodes.

31. A droplet actuator comprising a substrate comprising:

(a) a discrete flow section comprising electrodes arranged for conducting droplet operations on a substrate surface;

(b) a continuous flow section comprising a fluid path arranged for flowing a fluid therethrough, and separated from the discrete flow section by a barrier;

(c) an opening in the barrier arranged relative to the electrodes such that fluid in the fluid path is in proximity to one or more of the electrodes; and

(d) a capture surface comprising a component having an affinity for the target substance.

32. The droplet actuator of claim 31 wherein the electrodes are arranged to permit droplet operations which draw fluid comprising through the opening and form a droplet therefrom.

33. The droplet actuator of claim 31 wherein the droplet actuator further comprises sample collection beads immobilized in the fluid path.

34. The droplet actuator of claim 31 wherein the width of the opening is smaller than the height of the fluid path.

35. The droplet actuator of claim 31 wherein the continuous flow section comprises a second set of electrodes arranged for conducting droplet operations.

36. The droplet actuator of claim 31 comprising two or more capture surfaces in the continuous flow section.

37. The method of claim 36 wherein the two or more capture surfaces each comprise a population of beads, wherein each population has affinity for a different target substance.

38. The method of claim 37 wherein the beads are maintained in place by one or more physical barriers.

39. The method of claim 37 wherein the beads are magnetically responsive and are maintained in place by one or more magnetic fields.

40. The method of claim 39 wherein the magnetic field comprises a magnetic field committed by an electromagnet.

41. The method of claim 39 wherein the magnetic field comprises a magnetic field committed by a permanent magnet.

42. The droplet actuator of claim 31 comprising fluid in the fluid path, the fluid comprising a target substance and one or more beads having affinity for the target substance.

43. The droplet actuator of claim 31 wherein the target substance comprises an analyte of interest.

44. The droplet actuator of claim 31 wherein the target substance comprises a product of a chemical reaction.

45. The droplet actuator of claim 31 wherein the target substance comprises a bead.

46. The droplet actuator of claim 31 wherein the target substance comprises a bead comprising and in light of interest and/or a product of a chemical reaction.

47. The droplet actuator of claim 31 wherein the discrete flow section is separated from the continuous flow section by a reservoir comprising a reservoir electrode.

48. The droplet actuator of claim 31 further comprising a pressure source configured for forcing fluid through the fluid path.

49. The droplet actuator of claim 48 wherein the pressure source comprises a syringe coupled to the fluid path.

50. A method of conducting a chemical or biochemical reaction or interaction, the method comprising:

(a) providing a droplet actuator comprising a substrate comprising;

(i) a discrete flow section comprising electrodes arranged for conducting droplet operations on a substrate surface;

(ii) a continuous flow section comprising a fluid path arranged for flowing a fluid therethrough, and separated from the discrete flow section by a barrier;

(iii) an opening in the barrier arranged relative to the electrodes such that fluid in the fluid path is in proximity to one or more of the electrodes;

(iv) a capture surface comprising a component having an affinity for the target substance;

(b) flowing a fluid comprising the target substance through the fluid path;

(c) capturing the target substance on the capture surface; and

(d) conducting one or more droplet operations using the electrodes to transport a reagent into contact with the target substance and thereby conduct a chemical or biochemical reaction or interaction.

51. The method of claim 50 wherein the target substance comprises a cell and the biochemical interaction comprises interaction of the reagent with the cell.

52. A method of providing a droplet on a droplet actuator, the method comprising:

(a) providing a droplet actuator comprising a substrate comprising;

(i) a discrete flow section comprising electrodes arranged for conducting droplet operations on a substrate surface;

(ii) a continuous flow section comprising a fluid path arranged for flowing a fluid therethrough, and separated from the discrete flow section by a barrier;

(iii) an opening in the barrier arranged relative to the electrodes such that a droplet from the fluid path passing through the opening comes into proximity to one or more of the electrodes;

(b) flowing a filler fluid comprising the droplet through the fluid path;

(c) causing the droplet to pass through the opening into proximity with one or more of the electrodes to permit one or more electrode mediated droplet operations to be performed on the droplet.

53. The method of claim 52 further comprising recirculating the filler fluid through the fluid path via a recirculation path.

54. The method of claim 53 wherein the fluid path and/or the recirculation path comprises a filler fluid reservoir.

55. The method of claim 53 wherein the recirculation is facilitated using a pump to cause filler fluid to flow through the recirculation path.

56. The method of claim 52 wherein the droplet comprises a sample droplet.

57. The method of claim 52 wherein the droplet comprises a reagent droplet.

58. The method of claim 52 wherein step 52(c) is mediated by one or more of the electrodes.

59. The method of claim 52 wherein step 52(c) is mediated by a pressure forcing the droplet through the opening.