Castable three-dimensional stationary phase for electric field-driven applications

• US 20010008212A1
• Filed: 02/28/2001
• Published: 07/19/2001
• Est. Priority Date: 05/12/1999
• Status: Active Grant

• Current Assignee: National Technology & Engineering Solutions Of Sandia LLC (Honeywell International Inc.)
• Original Assignee: Sandia Corporation (Martin Marietta Corporation)
• Inventors: Shepodd, Timothy J., Even, William R. Jr., Whinnery, Leroy Jr.
• Granted Patent: US 6,846,399 B2
• Time in Patent Office: Days
• US Class Current: 204/451
• CPC Class Codes: G01N 27/44747 Composition of gel or of carrier mixture

Abstract

A polymer material useful as the porous dielectric medium for microfluidic devices generally and electrokinetic pumps in particular. The polymer material is produced from an inverse (water-in-oil) emulsion that creates a 3-dimensional network characterized by small pores and high internal volume, characteristics that are particularly desirable for the dielectric medium for electrokinetic pumps. Further, the material can be cast-to-shape inside a microchannel. The use of bifunctional monomers provides for charge density within the polymer structure sufficient to support electroosmotic flow. The 3-dimensional polymeric material can also be covalently bound to the channel walls thereby making it suitable for high-pressure applications.

Claims

1. A microfluidic device comprising an enclosed channel having a porous dielectric medium disposed therein and extending across the cross-sectional area of the channel, wherein the porous dielectric medium comprises a polymer having an internal structure formed by a 3-dimensional network of struts, and incorporated charged sites and prepared by an inverse emulsion process.

2. The device of

claim 1

, wherein said device comprises an electrokinetic pump.

3. The device of

claim 1

, wherein the polymer has the generic formula

—

(—

(A)_x—

(B)_y—

(C)_z—

)_q—

wherein, A, B, and C can be monovinyl, polyvinyl, and bifunctional monomer units, respectively and x, y, and z are greater than or equal 0 and can be equal or unequal, and q is greater than zero.

4. The device of

claim 3

, wherein the monovinyl monomer unit is styrene, methacrylonitrile, acrylates, vinyl pyridine, or methacrylates.

5. The device of

claim 3

, wherein the polyvinyl monomer unit is divinylbenzene, ethylene glycol dimethylacrylate, or trimethylolpropane trimethylacrylate.

6. The device of

claim 3

, wherein the bifunctional monomers are trialkoxysilyl functionalized monomers, sulfonates, phosphonates, boronates, alkyl ammonium, or ammonium compounds containing active vinyl groups.

7. The device of

claim 6

, wherein the bifunctional monomer includes trimethyloxysilylpropylmethacrylate, sodium vinyl sulfonate, vinyl phosphonic acid, or 4 vinyl phenylboronic acid.

8. The device of

claim 3

, further including acidic or basic functionalities.

9. The device of

claim 8

, wherein the functionality includes vinyl pyridine or vinyl imidazole.

10. A process for producing a microfluidic device comprising a channel having a porous dielectric material disposed therein, wherein the porous dielectric material comprises a polymer material having an internal structure formed by a 3-dimensional network of struts, and incorporated charged sites and the generic formula

—

(—

(A)_x—

(B)_y—

(C)_z—

)_q—

wherein, A, B, and C can be monovinyl, polyvinyl, and bifunctional monomers, respectively and x, y, and z are greater than or equal 0 and can be equal or unequal, and q is greater than zero, the process comprising the steps of;

a) preparing an water-in-oil emulsion, wherein the oil phase contains a mixture of monovinyl and polyvinyl monomers, a surfactant, and bifunctional monomers;

b) casting the emulsion into the channel;

c) polymerizing the monomers; and

d) exchanging the aqueous phase.

11. The process of

claim 10

, further including adding a polymerization initiator.

12. The process of

claim 11

, wherein the polymerization initiator includes peroxides, persulfates, or azo compounds.

13. The process of

claim 10

, wherein the step of polymerization includes thermal or optical initiation.

14. The process of

claim 10

, wherein the step of removing includes electroosmotic flow.

15. The process of

claim 10

, wherein the oil phase comprises about 11 wt % of the emulsion.

16. The process of

claim 10

, wherein the monovinyl monomer is styrene, methacrylonitrile, acrylates, vinyl pyridine, or methacrylates.

17. The process of

claim 10

, wherein the polyvinyl monomer is divinylbenzene, ethylene glycol dimethylacrylate, or trimethylolpropane trimethylacrylate.

18. The process of

claim 10

, wherein the bifunctional monomers are trialkoxysilyl functionalized monomers, sulfonates, phosphonates, boronates, alkyl ammonium, or ammonium compounds containing active vinyl groups.

19. The process of

claim 18

, wherein the bifunctional monomer includes trimethyloxysilylpropylmethacrylate, sodium vinyl sulfonate, vinyl phosphonic acid, or 4 vinyl phenylboronic acid.

20. The process of

claim 10

, further including acidic or basic functionalities.

21. The process of

claim 20

, wherein the functionality includes vinyl pyridine or vinyl imidazole.

22. The process of

claim 10

, further including the step of infusing a monomer mixture into the polymer network.

23. The process of

claim 10

, wherein the microfluidic device is an electrokinetic pump.