Apparatus and method for using electrostatic force to cause fluid movement

• US 7,147,763 B2
• Filed: 04/01/2002
• Issued: 12/12/2006
• Est. Priority Date: 04/01/2002
• Status: Active Grant

• Current Assignee: Palo Alto Research Center, Inc. (Xerox Holdings Corp.)
• Original Assignee: Palo Alto Research Center, Inc. (Xerox Holdings Corp.)
• Inventors: Bell, Alan G., Peeters, Eric, Torres, Francisco E., Biegelsen, David K., Elrod, Scott A., Dunec, John L.
• Primary Examiner(s): Nguyen, Nam
• Assistant Examiner(s): Barton, Jeffrey
• Application Number:
  US10/115,336
• Publication Number:
  US 20030183525A1
• Time in Patent Office: 1,716 Days
• Field of Search: 204/547, 204/643
• US Class Current: 204/547
• CPC Class Codes: B01F 25/14 Mixing drops, droplets or bodies of liquid which flow together or contact each other micromixers using where the materials to be mixed are in the form of droplets B01F33/302
• 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: B01J 2219/0036 Nozzles
• CPC Class Codes: B01J 2219/00527 Sheets
• 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 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: G02B 26/005 based on electrowetting

Abstract

A device for effecting motion of liquid droplets on a surface through the use of electrostatic field force includes a single substrate on which are disposed a plurality of spaced-apart electrodes. A dielectric material surrounds the electrodes on the substrate. The surface on which the liquid droplets are deposited is fabricated from a material that facilitates motion of the liquid droplets.

Claims

1. A method comprising:

depositing a first liquid droplet and a second liquid droplet on a surface with a spacing between said first liquid droplet and said second liquid droplet;

applying voltages to a set of two or more electrodes under said surface, said voltages causing one or both said first liquid droplet and said second liquid droplet to deform toward each other across said spacing;

in response to said voltages, said deformed droplets contacting each other and merging; and

wherein said first liquid droplet and said second liquid droplet support ion migration, each of said first and second liquid droplets having an adjacent surface, said adjacent surfaces being oppositely charged resulting from said ion migration responsive to said voltages, and the deformation of said first liquid droplet and said second liquid droplet responsive to an electrostatic force between said adjacent surfaces.

2. The method of claim 1, wherein said surface is disposed on a dielectric layer, wherein said dielectric layer surrounds said electrodes.

3. The method of claim 1, wherein said set of two or more electrodes comprises interdigitated electrode fingers.

4. The method of claim 2, wherein said voltages are provided by no more than two voltage sources.

5. The method of claim 1, wherein said surface comprises a hydrophobic surface.

6. The method of claim 1, wherein said surface comprises an oleophobic surface.

7. The method of claim 1, wherein the electrodes of said set of electrodes are separated by one or more gaps, at least one of said one or more gaps having a gap width between one micrometer to 500 micrometers.

8. The method of claim 1, wherein at least one of said set of electrodes has a size, said electrode size ranging from 10 micrometers to 10 millimeters on each side.

9. The method of claim 1, further comprising at least two voltage connections to said set of electrodes.

10. The method of claim 1, wherein each of said first liquid droplet and said second liquid droplet is smaller in size than said first electrode and said second electrode.

11. The method of claim 1, wherein said first liquid droplet and said second liquid droplet have at least one differing property.

12. The method of claim 1, wherein merging produces a chemical reaction within not less than one merged droplet.

13. The method of claim 1, wherein said first liquid droplet comprises a dielectric fluid and the deformation of said first liquid droplet is responsive to an electrostatic body force acting on said dielectric fluid;

said electrostatic body force responsive to an electric field established by said voltages.

14. The method of claim 13, wherein said electric field further comprises a fringe field.

15. The method of claim 14, wherein said set of two or more electrodes are a set of patterned interdigitated electrodes.