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

• US 6,846,399 B2
• Filed: 02/28/2001
• Issued: 01/25/2005
• Est. Priority Date: 05/12/1999
• Status: Expired due to Term

• Current Assignee: National Technology & Engineering Solutions Of Sandia LLC (Honeywell International Inc.)
• Original Assignee: Sandia National Laboratories (Government of the United States of America)
• Inventors: Shepodd, Timothy J., Even, William R. Jr., Whinnery, Leroy Jr.
• Primary Examiner(s): Nguyen, Nam
• Assistant Examiner(s): Mutschler, Brian L.
• Application Number:
  US09/796,762
• Publication Number:
  US 20010008212A1
• Time in Patent Office: 1,427 Days
• Field of Search: 204/450, 204/451, 204/455, 204/456, 204/465, 204/469, 204/470, 204/600, 204/601, 204/605, 204/606, 204/615, 521/64, 521/146, 521/149
• US Class Current: 204/470
• 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 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 are monovinyl, polyvinyl, and bifunctional monomers, respectively and x, y, and z are greater than or equal to zero and can be equal or unequal, and q is greater than zero, the process comprising the steps of;

a) preparing a water-in-oil emulsion, comprising an oil phase and an aqueous phase wherein the oil phase contains a surfactant, a polymerization initiator, and one or more of the monomers selected from the group of monovinyl, polyvinyl or bifunctional monomers;

b) casting the emulsion into the channel;

c) polymerizing the monomers by optical initiation; and

d) exchanging the aqueous phase.

2. The process of claim 1, wherein the polymerization initiator includes peroxides, persulfates, or azo compounds.

3. The process of claim 1, wherein the step of exchanging includes electroosmotic flow.

4. The process of claim 1, wherein the oil phase comprises about 11 wt % of the emulsion.

5. The process of claim 1, wherein the monovinyl monomer is styrene, methacrylonitrile, acrylates, vinyl pyridine, or methacrylates.

6. The process of claim 1, wherein the polyvinyl monomer is divinylbenzene, ethylene glycol dimethylacrylate, or trimethylolpropane trimethylacrylate.

7. The process of claim 1, wherein the bifunctional monomers are trialkoxysilyl functionalized monomers, sulfonates, phosphonates, boronates, alkyl ammonium, or ammonium compounds containing active vinyl groups.

8. The process of claim 7, wherein the bifunctional monomer includes trimethyloxysilylpropylmethacrylate, sodium vinyl sulfonate, vinyl phosphonic acid, or 4-vinyl phenylboronic acid.

9. The process of claim 1, wherein the polymer material further includes acidic or basic functionalities.

10. The process of claim 9, wherein the functionalities include vinyl pyridine or vinyl imidazole.

11. The process of claim 1, further including the step of infusing a monomer mixture into the polymer material.

12. The process of claim 1, wherein the microfluidic device is an electrokinetic pump.