Electrowetting-driven micropumping

• US 8,529,743 B2
• Filed: 07/25/2001
• Issued: 09/10/2013
• Est. Priority Date: 07/25/2000
• Status: Expired due to Term

• Current Assignee: Regents of the University of California (University of California)
• Original Assignee: Regents of the University of California (University of California)
• Inventors: Kim, Chang-Jin, Lee, Junghoon
• Primary Examiner(s): Denion, Thomas
• Assistant Examiner(s): TRAN, DIEM T
• Application Number:
  US10/343,261
• Publication Number:
  US 20030205632A1
• Time in Patent Office: 4,430 Days
• Field of Search: 204/450, 204/451, 204/454, 204/600, 204/601, 204/602, 345/37, 345/84, 345/107, 422/505, 417/48
• US Class Current: 204/450
• 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: B01L 2200/0605 Metering of fluids
• CPC Class Codes: B01L 2300/0819 Microarrays; Biochips
• CPC Class Codes: B01L 2300/0864 comprising only one inlet and multiple receiving wells, e.g. for separation, splitting
• 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 2300/161 Control and use of surface tension forces, e.g. hydrophobic, hydrophilic
• CPC Class Codes: B01L 2400/0415 electrical forces, e.g. electrokinetic
• CPC Class Codes: B01L 3/502784 specially adapted for droplet or plug flow, e.g. digital microfluidics automatic analysis using a stream of discrete samples in a tube system G01N35/08
• CPC Class Codes: B01L 3/502792 for moving individual droplets on a plate, e.g. by locally altering surface tension
• CPC Class Codes: F04B 17/00 Pumps characterised by combination with, or adaptation to, specific driving engines or motors
• CPC Class Codes: F04B 19/006 Micropumps F04B43/043 and F04B43/095 take precedence
• CPC Class Codes: G02B 26/005 based on electrowetting

Abstract

An apparatus and method fox micropumping is disclosed. The apparatus includes a virtual or physical microchannel and at least two hydrophobic electrode patches on a surface or two electrode patches disposed underneath a dielectric film proximate to the channel. Each of the electrode patches modifies a surface property between hydrophobic and hydrophilic states in response to an electrical potential applied between the liquid and the electrode, and the electrical potential is provided to digitize the liquid, drive the liquid segments, and mix different liquids.

Claims

1. An apparatus for micropumping, comprising:

a structure including one or more channels for a non-dielectric liquid; and

at least two hydrophobic electrode patches proximate to the channels;

wherein the electrode patches are sequentially charged to pump the liquid along the channels and to advance the liquid between at least two of the electrode patches, each of the electrode patches modifies a surface property of the structure between hydrophobic and hydrophilic states in response to an electrical potential applied between the liquid and the electrode patches, so that when the electric potential is applied between the liquid and the electrode patches, surfaces of the channels proximate to the electrode patches become hydrophilic and the liquid wets the surfaces of the channels proximate to the electrode patches, and

wherein complex manipulation of the liquid is performed, by digitizing the liquid using the electrode patches to separate increments of the liquid pumped along the channels, and by mixing segments of the liquid pumped along the channels using the electrode patches at junctions between the channels.

2. The apparatus of claim 1, wherein the electrode patches are arranged in an array.

3. The apparatus of claim 1, wherein the liquid is an electrolyte.

4. The apparatus of claim 1, wherein a segment of the liquid is driven by applying the electrical potential and wetting a first one of the electrodes at a first end of the segment while grounding and dewetting a second one of the electrodes at a second end of the segment.

5. The apparatus of claim 1, wherein the electrode patches are arranged along the one or more channels.

6. The apparatus of claim 1, further comprising a reservoir connected to one or more of the channels, wherein the electrode patches are positioned in the channels and draw liquid from the reservoir into the channels.

7. The apparatus of claim 1, wherein one or more of the channels include a breathing path to admit air into the channels to allow the liquid to flow freely in the channels.

8. The apparatus of claim 1, wherein the channels are virtual channels and no physical barriers define the virtual channels.

9. The apparatus of claim 1, wherein the electrical potential is applied between the liquid and the electrode patches by grounding a first one of the electrode patches to produce a hydrophobic state on a first region of the structure proximate the first one of the electrode patches and by applying the electric potential to a second one of the electrode patches to produce a hydrophilic state on a second region of the structure proximate the second one of the electrode patches.

10. The apparatus of claim 9, wherein a column of the liquid spans the first and second one of the electrode patches and a third one of the electrode patches proximate a middle section of the column of liquid is dewetted such that a liquid segment separates from the column of the liquid.

11. The apparatus of claim 1, further comprising one or more junctions, wherein each of the junctions connects two or more of the channels.

12. The apparatus of claim 11, wherein one of the electrode patches is positioned at each of the junctions.

13. The apparatus of claim 11, wherein the liquid is mixed with a second liquid at one or more of the junctions.

14. The apparatus of claim 11, wherein the channels and the junctions form a fluidic circuit.

15. The apparatus of claim 14, wherein the fluidic circuit is an m×

n grid of the channels and the junctions.

16. A method for micropumping, comprising the steps of:

providing a structure including one or more channels for a non-dielectric liquid;

forming at least two hydrophobic electrode patches proximate to the channels; and

sequentially charging the electrode patches to pump the liquid along the channels and to advance the liquid between at least two of the electrode patches, wherein an electrical potential is applied between the liquid and the electrode patches to modify a surface property of the structure between hydrophobic and hydrophilic states, so that when the electric potential is applied between the liquid and the electrode patches, surfaces of the channels proximate to the electrode patches become hydrophilic and the liquid wets the surfaces of the channels proximate to the electrode patches, and

wherein complex manipulation of the liquid is performed, by digitizing the liquid using the electrode patches to separate increments of the liquid pumped along the channels, and by mixing segments of the liquid pumped along the channels using the electrode patches at junctions between the channels.

17. The method of claim 16, wherein the electrode patches are arranged in an array.

18. The method of claim 16, wherein the liquid is an electrolyte.

19. The method of claim 16, wherein a segment of the liquid is driven by activating and wetting a first one of the electrode patches at a first end of the segment while grounding and dewetting a second one of the electrode patches at a second end of the segment.

20. The method of claim 16, wherein the electrode patches are arranged along the one or more channels.

21. The method of claim 16, further comprising a reservoir connected to one or more of the channels, and wherein the electrode patches are positioned in the channels and draw liquid from the reservoir into the channels.

22. The method of claim 16, wherein one or more of the channels includes a breathing path to admit air into the channels to allow the liquid to flow freely in the channels.

23. The method of claim 16, wherein the channels are virtual channels and no physical barriers define the virtual channels.

24. The method of claim 16, wherein the electrical potential is applied between the liquid and the electrode patches by grounding a first one of the electrode patches to produce a hydrophobic state on a first region of the structure proximate the first one of the electrode patches and by applying the electric potential to a second one of the electrode patches to produce a hydrophilic state on a second region of the structure proximate the second one of the electrode patches.

25. The method of claim 24, wherein a column of the liquid spans the first and second one of the electrode patches and a third one of the electrode patches proximate a middle section of the column of liquid is dewetted such that a liquid segment separates from the column of the liquid.

26. The method of claim 16, further comprising one or more junctions, wherein each of the junctions connect two or more of the channels.

27. The method of claim 26, wherein a one of the electrode patches is positioned at each of the junctions.

28. The method of claim 26, wherein the liquid is mixed with a second liquid at the one or more junctions.

29. The method of claim 26, wherein the channels and the junctions form a fluidic circuit.

30. The method of claim 29, wherein the fluidic circuit is an m×

n grid of the channels and the junctions.