Electropipettor and compensation means for electrophoretic bias

• US 6,287,520 B1
• Filed: 01/21/2000
• Issued: 09/11/2001
• Est. Priority Date: 06/28/1996
• Status: Expired due to Term

• Current Assignee: Caliper Holdings Incorporated
• Original Assignee: Caliper Holdings Incorporated
• Inventors: Parce, J. Wallace, Knapp, Michael R.
• Primary Examiner(s): Warden, Jill
• Assistant Examiner(s): STARSIAK, JOHN S
• Application Number:
  US09/488,801
• Time in Patent Office: 599 Days
• Field of Search: 204/450, 204/451, 204/452, 204/453, 204/454, 204/455, 204/600, 204/601, 204/602, 204/603, 204/604, 204/605, 422/100, 422/99, 422/101, 422/102, 422/103, 426/180, 435/288.3, 435/288.4, 435/288.5, 435/288.6, 435/288.7
• US Class Current: 422/503
• 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 33/30351 using hydrophilic/hydrophobic surfaces
• CPC Class Codes: B01F 33/30352 using roughness of the surfaces
• CPC Class Codes: B01J 19/0093 Microreactors, e.g. miniaturised or microfabricated reactors laboratory containers with capillary fluid transport in microfabricated channels or chambers B01L3/5027
• CPC Class Codes: B01J 2219/00891 Feeding or evacuation
• CPC Class Codes: B01L 2200/027 for microfluidic devices
• CPC Class Codes: B01L 2400/0415 electrical forces, e.g. electrokinetic
• CPC Class Codes: B01L 2400/0418 electro-osmotic flow [EOF]
• CPC Class Codes: B01L 2400/0421 electrophoretic flow
• CPC Class Codes: B01L 3/021 Pipettes, i.e. with only one conduit for withdrawing and redistributing liquids
• CPC Class Codes: B01L 3/502715 characterised by interfacing components, e.g. fluidic, electrical, optical or mechanical interfaces
• CPC Class Codes: B01L 3/50273 characterised by the means or forces applied to move the fluids micropumps F04B19/006, of the membrane type F04B43/043
• 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: 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: G01N 27/44704 Details; Accessories
• CPC Class Codes: G01N 27/44743 Introducing samples
• CPC Class Codes: G01N 27/44791 Microapparatus sample containers with integrated microfluidic structures B01L3/5027
• CPC Class Codes: H02N 11/006 Motors
• CPC Class Codes: Y10S 366/02 Micromixers: segmented laminar flow with boundary mixing orthogonal to the direction of fluid propagation with or without geometry influences from the pathway
• CPC Class Codes: Y10T 436/113332 : with conveyance of sample along a test line in a container or rack
• CPC Class Codes: Y10T 436/2575 : Volumetric liquid transfer

Abstract

The present invention provides for techniques for transporting materials using electrokinetic forces through the channels of a microfluidic system. The subject materials are transported in regions of high ionic concentration, next to spacer material regions of high ionic concentration, which are separated by spacer material regions of low ionic concentration. Such arrangements allow the materials to remain localized for the transport transit time to avoid mixing of the materials. Using these techniques, an electropipettor which is compatible with the microfluidic system is created so that materials can be easily introduced into the microfluidic system. The present invention also compensates for electrophoretic bias as materials are transported through the channels of the microfluidic system by splitting a channel into portions with positive and negative surface charges and a third electrode between the two portions, or by diffusion of the electrophoresing materials after transport along a channel.

Claims

1. A microfluidic device, comprising:

a body structure having at least first and second microfluidic channels disposed therein; and

a pipettor element extending from said body structure, said pipettor element having a third microfluidic channel disposed therethrough, the third microfluidic channel being open at a first end and fluidly connected to at least one of the first and second microfluidic channels at a second end, wherein the pipettor element is formed from at least a portion of the body structure.

2. The microfluidic device of claim 1, wherein the body structure comprises a planar body structure.

3. The microfluidic device of claim 2, wherein the pipettor element extends from a side of the planar body.

4. The microfluidic device of claim 3, wherein the pipettor element extends from the body structure in a same plane as the planar body structure.

5. The microfluidic device of claim 2, wherein the body structure comprises first and second planar substrates, the first and second microfluidic channels being defined between the first and second substrates.

6. The microfluidic device of claim 5, wherein the pipettor is formed from at least one of the first and second substrates.

7. The microfluidic device of claim 1, wherein the pipettor element is shaped at an end where the third channel is open.

8. The microfluidic device of claim 7, wherein the shaped end of the pipettor is beveled.

9. The microfluidic device of claim 1, wherein the body is comprised of glass.

10. The microfluidic device of claim 1, wherein the body is comprised of quartz.

11. The microfluidic device of claim 1, wherein the body is comprised of a polymer.

12. A method of fabricating a microfluidic device, comprising:

providing a body structure having at least first and second microfluidic channels disposed therein; and

forming a pipettor element from at least a portion of the body, the pipettor element extending from the body structure and including at least a third microfluidic channel disposed therethrough.

13. The method of claim 12, wherein the pipettor element is formed by etching away a portion of the body structure to form the pipettor element.

14. The method of claim 12, wherein the pipettor element is formed by cutting away a portion of the body structure to form the pipettor element.

15. The method of claim 12, wherein the pipettor element is formed by grinding away a portion of the body structure to form the pipettor element.

16. The method of claim 12, wherein the pipettor element is formed by abrading away a portion of the body structure to form the pipettor element.

17. The method of claim 12, wherein:

the providing step comprises;

fabricating at least first, second and third microfluidic channel segments in the body, the first, second and third microfluidic channel segments being in fluid communication;

removing a portion of the body to form a pipettor element extending from the body, such that the third microfluidic channel segment extends through a length of the pipettor element.

18. The method of claim 17, wherein the step of fabricating the first, second and third microfluidic channel segments in the body comprises fabricating first, second and third interconnected grooves in a first substrate surface, and overlaying and bonding a second substrate to the first substrate surface to seal the first, second and third grooves, to form the first, second and third microfluidic channel segments.

19. The method of claim 18, wherein the step of fabricating the first, second and third interconnecting grooves comprises etching the first, second and third grooves into the first substrate surface.

20. The method of claim 18, wherein the step of fabricating the first, second and third interconnecting grooves comprises molding the first, second and third grooves into the first substrate surface.

21. The method of claim 12, wherein the body structure comprises glass.

22. The method of claim 12, wherein the body structure comprises quartz.

23. The method of claim 12, wherein the body structure comprises a polymer.

24. The method of claim 23, wherein the step of fabricating the first, second and third interconnecting grooves comprises stamp molding the first, second and third grooves into the fast substrate surface.

25. The method of claim 23, wherein the step of fabricating the first, second and third interconnecting grooves comprises machining the first, second and third grooves into the first substrate surface.